I got the no/low compression blues


Bruce Dewing
 

Some advice please.  I'm helping a friend with his 71 Honda 600 sedan (you know, those motorcycle engine cars).  Compression test right side, it went from 80 psi, to 50 psi (wet) to 20 psi to 25 psi to zero psi  in 10 minutes time.  With piston at TDC, I did a hillbilly leakdown test (no leakdown gauge, just connected a 3 gallon air tank w/gauge to the cylinder).  No change with the tank gauge, listened with a mechanics stethoscope & didn't hear anything.  Then adjusted loose intake valve and pressure is now 30 psi.
Am I missing something?

Bruce
Grass Valley, CA


Ken Nelson
 

Hi Bruce, this is a 2 cyl right?  Did you do a spinning compression test with plugs out, carb throttle plate full open PER cylinder, if each cyl has its own carb - then spin with starter & compression test gauge which holds pressure?  That's the only way I know to get a true reading, and many guys forget to hold the throttle wide open to allow free movement of air to cyl.  Those pressures are just too wacky to interpret from my end.   How did you get the original 80, then 50, then 20 psi to zero??  
if you did nothing more than spin engine with both plugs out, and listened to the air pumping in/out of each cyl, and they sounded definitely different, then I'd suspect burnt valve, broken rings or something - 
I once had a Citroen DS19 4 banger basically stop wanting to run when No. 1 cyl dropped to 70 psi from 140 or so.  Turned out none of the 4 pistons had complete rings, just cracked pieces in each groove, except for no. 1 piston.  That one had NO upper ring at all - just carbon-filled groove.  My leadfooted son ran it so hard the piston crown melted thru at pt above the no - ring groove, and compression dropped as result.  But ALL the remaining rings were broken but in grooves except for that first one, and I'm surprised the engine ran for over a yr at all!  

Could a hole have melted thru the piston crown?  It's been known to happen - Got a borescope for your smartphone?  I've heard they're as cheap as 20 bucks on the web - 

Ken

On Tue, Dec 1, 2020 at 4:06 PM Bruce Dewing via groups.io <tralfaz42=yahoo.com@groups.io> wrote:
Some advice please.  I'm helping a friend with his 71 Honda 600 sedan (you know, those motorcycle engine cars).  Compression test right side, it went from 80 psi, to 50 psi (wet) to 20 psi to 25 psi to zero psi  in 10 minutes time.  With piston at TDC, I did a hillbilly leakdown test (no leakdown gauge, just connected a 3 gallon air tank w/gauge to the cylinder).  No change with the tank gauge, listened with a mechanics stethoscope & didn't hear anything.  Then adjusted loose intake valve and pressure is now 30 psi.
Am I missing something?

Bruce
Grass Valley, CA


David Russel
 

Ken

Think he’s doing a leak down tester without a real leak down tester. First number is starting press and second is what it leaked down to. 

Did I get it right Bruce?

David 

Sent From Mobile Phone

On Dec 1, 2020, at 6:09 PM, Ken Nelson <citbuff@...> wrote:


Hi Bruce, this is a 2 cyl right?  Did you do a spinning compression test with plugs out, carb throttle plate full open PER cylinder, if each cyl has its own carb - then spin with starter & compression test gauge which holds pressure?  That's the only way I know to get a true reading, and many guys forget to hold the throttle wide open to allow free movement of air to cyl.  Those pressures are just too wacky to interpret from my end.   How did you get the original 80, then 50, then 20 psi to zero??  
if you did nothing more than spin engine with both plugs out, and listened to the air pumping in/out of each cyl, and they sounded definitely different, then I'd suspect burnt valve, broken rings or something - 
I once had a Citroen DS19 4 banger basically stop wanting to run when No. 1 cyl dropped to 70 psi from 140 or so.  Turned out none of the 4 pistons had complete rings, just cracked pieces in each groove, except for no. 1 piston.  That one had NO upper ring at all - just carbon-filled groove.  My leadfooted son ran it so hard the piston crown melted thru at pt above the no - ring groove, and compression dropped as result.  But ALL the remaining rings were broken but in grooves except for that first one, and I'm surprised the engine ran for over a yr at all!  

Could a hole have melted thru the piston crown?  It's been known to happen - Got a borescope for your smartphone?  I've heard they're as cheap as 20 bucks on the web - 

Ken

On Tue, Dec 1, 2020 at 4:06 PM Bruce Dewing via groups.io <tralfaz42=yahoo.com@groups.io> wrote:
Some advice please.  I'm helping a friend with his 71 Honda 600 sedan (you know, those motorcycle engine cars).  Compression test right side, it went from 80 psi, to 50 psi (wet) to 20 psi to 25 psi to zero psi  in 10 minutes time.  With piston at TDC, I did a hillbilly leakdown test (no leakdown gauge, just connected a 3 gallon air tank w/gauge to the cylinder).  No change with the tank gauge, listened with a mechanics stethoscope & didn't hear anything.  Then adjusted loose intake valve and pressure is now 30 psi.
Am I missing something?

Bruce
Grass Valley, CA


Ken Nelson
 

Whatever David, but I sure wouldn't trust those nos.  Any parts store will loan a real compression tester free - 

Ken

On Tue, Dec 1, 2020 at 9:23 PM David Russel <djrussel@...> wrote:
Ken

Think he’s doing a leak down tester without a real leak down tester. First number is starting press and second is what it leaked down to. 

Did I get it right Bruce?

David 

Sent From Mobile Phone

On Dec 1, 2020, at 6:09 PM, Ken Nelson <citbuff@...> wrote:


Hi Bruce, this is a 2 cyl right?  Did you do a spinning compression test with plugs out, carb throttle plate full open PER cylinder, if each cyl has its own carb - then spin with starter & compression test gauge which holds pressure?  That's the only way I know to get a true reading, and many guys forget to hold the throttle wide open to allow free movement of air to cyl.  Those pressures are just too wacky to interpret from my end.   How did you get the original 80, then 50, then 20 psi to zero??  
if you did nothing more than spin engine with both plugs out, and listened to the air pumping in/out of each cyl, and they sounded definitely different, then I'd suspect burnt valve, broken rings or something - 
I once had a Citroen DS19 4 banger basically stop wanting to run when No. 1 cyl dropped to 70 psi from 140 or so.  Turned out none of the 4 pistons had complete rings, just cracked pieces in each groove, except for no. 1 piston.  That one had NO upper ring at all - just carbon-filled groove.  My leadfooted son ran it so hard the piston crown melted thru at pt above the no - ring groove, and compression dropped as result.  But ALL the remaining rings were broken but in grooves except for that first one, and I'm surprised the engine ran for over a yr at all!  

Could a hole have melted thru the piston crown?  It's been known to happen - Got a borescope for your smartphone?  I've heard they're as cheap as 20 bucks on the web - 

Ken

On Tue, Dec 1, 2020 at 4:06 PM Bruce Dewing via groups.io <tralfaz42=yahoo.com@groups.io> wrote:
Some advice please.  I'm helping a friend with his 71 Honda 600 sedan (you know, those motorcycle engine cars).  Compression test right side, it went from 80 psi, to 50 psi (wet) to 20 psi to 25 psi to zero psi  in 10 minutes time.  With piston at TDC, I did a hillbilly leakdown test (no leakdown gauge, just connected a 3 gallon air tank w/gauge to the cylinder).  No change with the tank gauge, listened with a mechanics stethoscope & didn't hear anything.  Then adjusted loose intake valve and pressure is now 30 psi.
Am I missing something?

Bruce
Grass Valley, CA


Bruce Dewing
 

Ken,
Yes, I'm using a real compression tester (screw in). 

David,
I've ordered a leak down tester.  A couple of days out tho.

The values given are a regular compression test dry (80 lbs)  2 minutes later wet (50 lbs) then again 20 lbs, then 25 lbs, then zero.  Used a 2nd (hand held, jamb it in the hole) compression tester showing 0 psi.  Two days later, I was cranking it over with my index finger sealing the spark plug hole, with little resistance.  It's a two cylinder upright, will try again with the carb off and both plugs out.

I don't have a smart phone but do have usb video camera/cable, will give it a go.

Thanks for your input,  Bruce




On Tuesday, December 1, 2020, 8:10:46 PM PST, Ken Nelson <citbuff@...> wrote:


Whatever David, but I sure wouldn't trust those nos.  Any parts store will loan a real compression tester free - 

Ken

On Tue, Dec 1, 2020 at 9:23 PM David Russel <djrussel@...> wrote:
Ken

Think he’s doing a leak down tester without a real leak down tester. First number is starting press and second is what it leaked down to. 

Did I get it right Bruce?

David 

Sent From Mobile Phone

On Dec 1, 2020, at 6:09 PM, Ken Nelson <citbuff@...> wrote:


Hi Bruce, this is a 2 cyl right?  Did you do a spinning compression test with plugs out, carb throttle plate full open PER cylinder, if each cyl has its own carb - then spin with starter & compression test gauge which holds pressure?  That's the only way I know to get a true reading, and many guys forget to hold the throttle wide open to allow free movement of air to cyl.  Those pressures are just too wacky to interpret from my end.   How did you get the original 80, then 50, then 20 psi to zero??  
if you did nothing more than spin engine with both plugs out, and listened to the air pumping in/out of each cyl, and they sounded definitely different, then I'd suspect burnt valve, broken rings or something - 
I once had a Citroen DS19 4 banger basically stop wanting to run when No. 1 cyl dropped to 70 psi from 140 or so.  Turned out none of the 4 pistons had complete rings, just cracked pieces in each groove, except for no. 1 piston.  That one had NO upper ring at all - just carbon-filled groove.  My leadfooted son ran it so hard the piston crown melted thru at pt above the no - ring groove, and compression dropped as result.  But ALL the remaining rings were broken but in grooves except for that first one, and I'm surprised the engine ran for over a yr at all!  

Could a hole have melted thru the piston crown?  It's been known to happen - Got a borescope for your smartphone?  I've heard they're as cheap as 20 bucks on the web - 

Ken

On Tue, Dec 1, 2020 at 4:06 PM Bruce Dewing via groups.io <tralfaz42=yahoo.com@groups.io> wrote:
Some advice please.  I'm helping a friend with his 71 Honda 600 sedan (you know, those motorcycle engine cars).  Compression test right side, it went from 80 psi, to 50 psi (wet) to 20 psi to 25 psi to zero psi  in 10 minutes time.  With piston at TDC, I did a hillbilly leakdown test (no leakdown gauge, just connected a 3 gallon air tank w/gauge to the cylinder).  No change with the tank gauge, listened with a mechanics stethoscope & didn't hear anything.  Then adjusted loose intake valve and pressure is now 30 psi.
Am I missing something?

Bruce
Grass Valley, CA


Ken Nelson
 

Another thought Bruce:  I once started an engine which had sat over the winter in Chicago.  When I first cranked it over in spring, I heard immediately two loud "clanks", then stopped the process.  Turned engine over by hand (crankable Citroen), and got no noise.  2000 miles later, halfway home from Disneyworld to Chitown, stopped, had lunch, moved car, started & sounded like rod had let go.  
Long story short, pulled entire drivetrain - engine/trans - ran on floor, same noise.  Pulled pan, checked all bearings, nothing.  pulled head, found pieces of intake valve guide on top of valve in no. 3 cyl. 
A valve had hung open from rust just as I first started engine, but came loose, made no more noise and car ran like top.  The valve had been nicked by piston, just enough to bend it a hair, and side force on guide had fatigued it til it split off base, then hammering on valve head, split in half!  Pieces being too large to go thru port, that saved the head.  I fished out, found Toyota guide same dimensions, replaced, shop banged valve straight, trued seat, l never had to change it & made it 900 miles home.  

SO - maybe you've got a sticking valve that varies in its stickiness, so varies opening to give you erratic pressure readings, then hangs completely - can you pull valve cover & check stem position?  That's the only thing that makes any sense here - or broken spring?  Lost keeper?  Let us know what you find - this one is curious! 

Ken

On Tue, Dec 1, 2020 at 8:44 PM Bruce Dewing via groups.io <tralfaz42=yahoo.com@groups.io> wrote:
Ken,
Yes, I'm using a real compression tester (screw in). 

David,
I've ordered a leak down tester.  A couple of days out tho.

The values given are a regular compression test dry (80 lbs)  2 minutes later wet (50 lbs) then again 20 lbs, then 25 lbs, then zero.  Used a 2nd (hand held, jamb it in the hole) compression tester showing 0 psi.  Two days later, I was cranking it over with my index finger sealing the spark plug hole, with little resistance.  It's a two cylinder upright, will try again with the carb off and both plugs out.

I don't have a smart phone but do have usb video camera/cable, will give it a go.

Thanks for your input,  Bruce




On Tuesday, December 1, 2020, 8:10:46 PM PST, Ken Nelson <citbuff@...> wrote:


Whatever David, but I sure wouldn't trust those nos.  Any parts store will loan a real compression tester free - 

Ken

On Tue, Dec 1, 2020 at 9:23 PM David Russel <djrussel@...> wrote:
Ken

Think he’s doing a leak down tester without a real leak down tester. First number is starting press and second is what it leaked down to. 

Did I get it right Bruce?

David 

Sent From Mobile Phone

On Dec 1, 2020, at 6:09 PM, Ken Nelson <citbuff@...> wrote:


Hi Bruce, this is a 2 cyl right?  Did you do a spinning compression test with plugs out, carb throttle plate full open PER cylinder, if each cyl has its own carb - then spin with starter & compression test gauge which holds pressure?  That's the only way I know to get a true reading, and many guys forget to hold the throttle wide open to allow free movement of air to cyl.  Those pressures are just too wacky to interpret from my end.   How did you get the original 80, then 50, then 20 psi to zero??  
if you did nothing more than spin engine with both plugs out, and listened to the air pumping in/out of each cyl, and they sounded definitely different, then I'd suspect burnt valve, broken rings or something - 
I once had a Citroen DS19 4 banger basically stop wanting to run when No. 1 cyl dropped to 70 psi from 140 or so.  Turned out none of the 4 pistons had complete rings, just cracked pieces in each groove, except for no. 1 piston.  That one had NO upper ring at all - just carbon-filled groove.  My leadfooted son ran it so hard the piston crown melted thru at pt above the no - ring groove, and compression dropped as result.  But ALL the remaining rings were broken but in grooves except for that first one, and I'm surprised the engine ran for over a yr at all!  

Could a hole have melted thru the piston crown?  It's been known to happen - Got a borescope for your smartphone?  I've heard they're as cheap as 20 bucks on the web - 

Ken

On Tue, Dec 1, 2020 at 4:06 PM Bruce Dewing via groups.io <tralfaz42=yahoo.com@groups.io> wrote:
Some advice please.  I'm helping a friend with his 71 Honda 600 sedan (you know, those motorcycle engine cars).  Compression test right side, it went from 80 psi, to 50 psi (wet) to 20 psi to 25 psi to zero psi  in 10 minutes time.  With piston at TDC, I did a hillbilly leakdown test (no leakdown gauge, just connected a 3 gallon air tank w/gauge to the cylinder).  No change with the tank gauge, listened with a mechanics stethoscope & didn't hear anything.  Then adjusted loose intake valve and pressure is now 30 psi.
Am I missing something?

Bruce
Grass Valley, CA


Fred Cisin
 

The cam is chain driven.
Check to see if the chain has slipped a link or two on the cam sprocket.

(Is the cam timing correct?)


Ken Nelson
 

Bruce, how does other cyl compare??  If chain jumped as Fred suggested, both valves/cyls should be effected similarly, yes?  

Ken

On Tue, Dec 1, 2020 at 10:13 PM Fred Cisin <cisin@...> wrote:
The cam is chain driven.
Check to see if the chain has slipped a link or two on the cam sprocket.

(Is the cam timing correct?)










David Russel
 

Bruce,

I was just looking at getting a leak down tester from Harbor Ft, one on clearance for $25, Store purchase only.  OOPs, no local stores around here have any in stock.  Never thought to ask but will see if O'Reilly has them to lend.

Did a compression test yesterday on the single cylinder R27 and given the power needed to kick it over was surprised at 80 psi dry, and hardly up any with oil.  Was sad and was thinking about buying a more expensive leak-down than I need, just to track down the problem area.  Din't need a tester to ID the problem area as it was ME.  Neglected to open the throttle.  Tested today, throttle open and got 120 psi dry and didn't bother with oil as this reading is good enough

have a H FT borescope and yesterday discovered the camera/light unit is too fat to pass thru the spark plug hole.  Would not have bought the scope if I'd realized the no-fit size.  It was possible to use it to peer into the  cylinder but didn't get to see much and don't have the experience/knowledge to interpret what it showed other than the top of the piston being black and not having a hole, both of which I knew without looking.

Good luck on your cycle engine project.  Assume it is a 4 stroke so easy enough to verify that both pistons are sliding up and back, then with valve covers off the valve movement can be checked.  Leak down tester might do you a lot of good.

David


On Tue, Dec 1, 2020 at 8:44 PM Bruce Dewing via groups.io <tralfaz42=yahoo.com@groups.io> wrote:
Ken,
Yes, I'm using a real compression tester (screw in). 

David,
I've ordered a leak down tester.  A couple of days out tho.

The values given are a regular compression test dry (80 lbs)  2 minutes later wet (50 lbs) then again 20 lbs, then 25 lbs, then zero.  Used a 2nd (hand held, jamb it in the hole) compression tester showing 0 psi.  Two days later, I was cranking it over with my index finger sealing the spark plug hole, with little resistance.  It's a two cylinder upright, will try again with the carb off and both plugs out.

I don't have a smart phone but do have usb video camera/cable, will give it a go.

Thanks for your input,  Bruce




On Tuesday, December 1, 2020, 8:10:46 PM PST, Ken Nelson <citbuff@...> wrote:


Whatever David, but I sure wouldn't trust those nos.  Any parts store will loan a real compression tester free - 

Ken

On Tue, Dec 1, 2020 at 9:23 PM David Russel <djrussel@...> wrote:
Ken

Think he’s doing a leak down tester without a real leak down tester. First number is starting press and second is what it leaked down to. 

Did I get it right Bruce?

David 

Sent From Mobile Phone

On Dec 1, 2020, at 6:09 PM, Ken Nelson <citbuff@...> wrote:


Hi Bruce, this is a 2 cyl right?  Did you do a spinning compression test with plugs out, carb throttle plate full open PER cylinder, if each cyl has its own carb - then spin with starter & compression test gauge which holds pressure?  That's the only way I know to get a true reading, and many guys forget to hold the throttle wide open to allow free movement of air to cyl.  Those pressures are just too wacky to interpret from my end.   How did you get the original 80, then 50, then 20 psi to zero??  
if you did nothing more than spin engine with both plugs out, and listened to the air pumping in/out of each cyl, and they sounded definitely different, then I'd suspect burnt valve, broken rings or something - 
I once had a Citroen DS19 4 banger basically stop wanting to run when No. 1 cyl dropped to 70 psi from 140 or so.  Turned out none of the 4 pistons had complete rings, just cracked pieces in each groove, except for no. 1 piston.  That one had NO upper ring at all - just carbon-filled groove.  My leadfooted son ran it so hard the piston crown melted thru at pt above the no - ring groove, and compression dropped as result.  But ALL the remaining rings were broken but in grooves except for that first one, and I'm surprised the engine ran for over a yr at all!  

Could a hole have melted thru the piston crown?  It's been known to happen - Got a borescope for your smartphone?  I've heard they're as cheap as 20 bucks on the web - 

Ken

On Tue, Dec 1, 2020 at 4:06 PM Bruce Dewing via groups.io <tralfaz42=yahoo.com@groups.io> wrote:
Some advice please.  I'm helping a friend with his 71 Honda 600 sedan (you know, those motorcycle engine cars).  Compression test right side, it went from 80 psi, to 50 psi (wet) to 20 psi to 25 psi to zero psi  in 10 minutes time.  With piston at TDC, I did a hillbilly leakdown test (no leakdown gauge, just connected a 3 gallon air tank w/gauge to the cylinder).  No change with the tank gauge, listened with a mechanics stethoscope & didn't hear anything.  Then adjusted loose intake valve and pressure is now 30 psi.
Am I missing something?

Bruce
Grass Valley, CA


Bruce Dewing
 

Ken, a sticky valve may explain the symptoms. 

David, I've ordered a leak down tester on Amazon, also $25.  Valves do move.

Fred, yes cam is where it belongs.  Cam chain is acceptable, passed stretch test.

Other piston shows 137 psi consistently.  Checked head bolt torque too (only 4 of 8 are accessible with camshaft in place).  To be continued.

Bruce



On Wednesday, December 2, 2020, 12:15:16 AM PST, David Russel <djrussel@...> wrote:


Bruce,

I was just looking at getting a leak down tester from Harbor Ft, one on clearance for $25, Store purchase only.  OOPs, no local stores around here have any in stock.  Never thought to ask but will see if O'Reilly has them to lend.

Did a compression test yesterday on the single cylinder R27 and given the power needed to kick it over was surprised at 80 psi dry, and hardly up any with oil.  Was sad and was thinking about buying a more expensive leak-down than I need, just to track down the problem area.  Din't need a tester to ID the problem area as it was ME.  Neglected to open the throttle.  Tested today, throttle open and got 120 psi dry and didn't bother with oil as this reading is good enough

have a H FT borescope and yesterday discovered the camera/light unit is too fat to pass thru the spark plug hole.  Would not have bought the scope if I'd realized the no-fit size.  It was possible to use it to peer into the  cylinder but didn't get to see much and don't have the experience/knowledge to interpret what it showed other than the top of the piston being black and not having a hole, both of which I knew without looking.

Good luck on your cycle engine project.  Assume it is a 4 stroke so easy enough to verify that both pistons are sliding up and back, then with valve covers off the valve movement can be checked.  Leak down tester might do you a lot of good.

David

On Tue, Dec 1, 2020 at 8:44 PM Bruce Dewing via groups.io <tralfaz42=yahoo.com@groups.io> wrote:
Ken,
Yes, I'm using a real compression tester (screw in). 

David,
I've ordered a leak down tester.  A couple of days out tho.

The values given are a regular compression test dry (80 lbs)  2 minutes later wet (50 lbs) then again 20 lbs, then 25 lbs, then zero.  Used a 2nd (hand held, jamb it in the hole) compression tester showing 0 psi.  Two days later, I was cranking it over with my index finger sealing the spark plug hole, with little resistance.  It's a two cylinder upright, will try again with the carb off and both plugs out.

I don't have a smart phone but do have usb video camera/cable, will give it a go.

Thanks for your input,  Bruce




On Tuesday, December 1, 2020, 8:10:46 PM PST, Ken Nelson <citbuff@...> wrote:


Whatever David, but I sure wouldn't trust those nos.  Any parts store will loan a real compression tester free - 

Ken

On Tue, Dec 1, 2020 at 9:23 PM David Russel <djrussel@...> wrote:
Ken

Think he’s doing a leak down tester without a real leak down tester. First number is starting press and second is what it leaked down to. 

Did I get it right Bruce?

David 

Sent From Mobile Phone

On Dec 1, 2020, at 6:09 PM, Ken Nelson <citbuff@...> wrote:


Hi Bruce, this is a 2 cyl right?  Did you do a spinning compression test with plugs out, carb throttle plate full open PER cylinder, if each cyl has its own carb - then spin with starter & compression test gauge which holds pressure?  That's the only way I know to get a true reading, and many guys forget to hold the throttle wide open to allow free movement of air to cyl.  Those pressures are just too wacky to interpret from my end.   How did you get the original 80, then 50, then 20 psi to zero??  
if you did nothing more than spin engine with both plugs out, and listened to the air pumping in/out of each cyl, and they sounded definitely different, then I'd suspect burnt valve, broken rings or something - 
I once had a Citroen DS19 4 banger basically stop wanting to run when No. 1 cyl dropped to 70 psi from 140 or so.  Turned out none of the 4 pistons had complete rings, just cracked pieces in each groove, except for no. 1 piston.  That one had NO upper ring at all - just carbon-filled groove.  My leadfooted son ran it so hard the piston crown melted thru at pt above the no - ring groove, and compression dropped as result.  But ALL the remaining rings were broken but in grooves except for that first one, and I'm surprised the engine ran for over a yr at all!  

Could a hole have melted thru the piston crown?  It's been known to happen - Got a borescope for your smartphone?  I've heard they're as cheap as 20 bucks on the web - 

Ken

On Tue, Dec 1, 2020 at 4:06 PM Bruce Dewing via groups.io <tralfaz42=yahoo.com@groups.io> wrote:
Some advice please.  I'm helping a friend with his 71 Honda 600 sedan (you know, those motorcycle engine cars).  Compression test right side, it went from 80 psi, to 50 psi (wet) to 20 psi to 25 psi to zero psi  in 10 minutes time.  With piston at TDC, I did a hillbilly leakdown test (no leakdown gauge, just connected a 3 gallon air tank w/gauge to the cylinder).  No change with the tank gauge, listened with a mechanics stethoscope & didn't hear anything.  Then adjusted loose intake valve and pressure is now 30 psi.
Am I missing something?

Bruce
Grass Valley, CA


Ken Nelson
 

Can you tell if the valves of that cyl are seating completely?  Is throttleplate being held completely open during test?  Is carb linkage working properly?  ls valve adjusting screw loose in its threads?  Is it pushrod or OHC driving the valve?  If operated by a rocker arm, is that part worn/loose/getting stuck?  lf pushrod-operated rocker, is pushrod bent/flopping around?  Are there two springs closing valve - one inside the other - that could somehow be broken/binding on each other?  
When did engine last run right?  Or has it been stored a long time?  History?  

Ken


On Wed, Dec 2, 2020 at 8:45 AM Bruce Dewing via groups.io <tralfaz42=yahoo.com@groups.io> wrote:
Ken, a sticky valve may explain the symptoms. 

David, I've ordered a leak down tester on Amazon, also $25.  Valves do move.

Fred, yes cam is where it belongs.  Cam chain is acceptable, passed stretch test.

Other piston shows 137 psi consistently.  Checked head bolt torque too (only 4 of 8 are accessible with camshaft in place).  To be continued.

Bruce



On Wednesday, December 2, 2020, 12:15:16 AM PST, David Russel <djrussel@...> wrote:


Bruce,

I was just looking at getting a leak down tester from Harbor Ft, one on clearance for $25, Store purchase only.  OOPs, no local stores around here have any in stock.  Never thought to ask but will see if O'Reilly has them to lend.

Did a compression test yesterday on the single cylinder R27 and given the power needed to kick it over was surprised at 80 psi dry, and hardly up any with oil.  Was sad and was thinking about buying a more expensive leak-down than I need, just to track down the problem area.  Din't need a tester to ID the problem area as it was ME.  Neglected to open the throttle.  Tested today, throttle open and got 120 psi dry and didn't bother with oil as this reading is good enough

have a H FT borescope and yesterday discovered the camera/light unit is too fat to pass thru the spark plug hole.  Would not have bought the scope if I'd realized the no-fit size.  It was possible to use it to peer into the  cylinder but didn't get to see much and don't have the experience/knowledge to interpret what it showed other than the top of the piston being black and not having a hole, both of which I knew without looking.

Good luck on your cycle engine project.  Assume it is a 4 stroke so easy enough to verify that both pistons are sliding up and back, then with valve covers off the valve movement can be checked.  Leak down tester might do you a lot of good.

David

On Tue, Dec 1, 2020 at 8:44 PM Bruce Dewing via groups.io <tralfaz42=yahoo.com@groups.io> wrote:
Ken,
Yes, I'm using a real compression tester (screw in). 

David,
I've ordered a leak down tester.  A couple of days out tho.

The values given are a regular compression test dry (80 lbs)  2 minutes later wet (50 lbs) then again 20 lbs, then 25 lbs, then zero.  Used a 2nd (hand held, jamb it in the hole) compression tester showing 0 psi.  Two days later, I was cranking it over with my index finger sealing the spark plug hole, with little resistance.  It's a two cylinder upright, will try again with the carb off and both plugs out.

I don't have a smart phone but do have usb video camera/cable, will give it a go.

Thanks for your input,  Bruce




On Tuesday, December 1, 2020, 8:10:46 PM PST, Ken Nelson <citbuff@...> wrote:


Whatever David, but I sure wouldn't trust those nos.  Any parts store will loan a real compression tester free - 

Ken

On Tue, Dec 1, 2020 at 9:23 PM David Russel <djrussel@...> wrote:
Ken

Think he’s doing a leak down tester without a real leak down tester. First number is starting press and second is what it leaked down to. 

Did I get it right Bruce?

David 

Sent From Mobile Phone

On Dec 1, 2020, at 6:09 PM, Ken Nelson <citbuff@...> wrote:


Hi Bruce, this is a 2 cyl right?  Did you do a spinning compression test with plugs out, carb throttle plate full open PER cylinder, if each cyl has its own carb - then spin with starter & compression test gauge which holds pressure?  That's the only way I know to get a true reading, and many guys forget to hold the throttle wide open to allow free movement of air to cyl.  Those pressures are just too wacky to interpret from my end.   How did you get the original 80, then 50, then 20 psi to zero??  
if you did nothing more than spin engine with both plugs out, and listened to the air pumping in/out of each cyl, and they sounded definitely different, then I'd suspect burnt valve, broken rings or something - 
I once had a Citroen DS19 4 banger basically stop wanting to run when No. 1 cyl dropped to 70 psi from 140 or so.  Turned out none of the 4 pistons had complete rings, just cracked pieces in each groove, except for no. 1 piston.  That one had NO upper ring at all - just carbon-filled groove.  My leadfooted son ran it so hard the piston crown melted thru at pt above the no - ring groove, and compression dropped as result.  But ALL the remaining rings were broken but in grooves except for that first one, and I'm surprised the engine ran for over a yr at all!  

Could a hole have melted thru the piston crown?  It's been known to happen - Got a borescope for your smartphone?  I've heard they're as cheap as 20 bucks on the web - 

Ken

On Tue, Dec 1, 2020 at 4:06 PM Bruce Dewing via groups.io <tralfaz42=yahoo.com@groups.io> wrote:
Some advice please.  I'm helping a friend with his 71 Honda 600 sedan (you know, those motorcycle engine cars).  Compression test right side, it went from 80 psi, to 50 psi (wet) to 20 psi to 25 psi to zero psi  in 10 minutes time.  With piston at TDC, I did a hillbilly leakdown test (no leakdown gauge, just connected a 3 gallon air tank w/gauge to the cylinder).  No change with the tank gauge, listened with a mechanics stethoscope & didn't hear anything.  Then adjusted loose intake valve and pressure is now 30 psi.
Am I missing something?

Bruce
Grass Valley, CA


Fred Cisin
 

On Wed, 2 Dec 2020, Ken Nelson wrote:
Can you tell if the valves of that cyl are seating completely? Is
throttleplate being held completely open during test?
And, it's variable venturi.

Is carb linkage working properly?
right up top, easy to hold the throttle open with your other hand.

ls valve adjusting screw loose in its threads? Is it
pushrod or OHC driving the valve? If operated by a rocker arm, is that
part worn/loose/getting stuck? lf pushrod-operated rocker, is pushrod
bent/flopping around?
overhead cam, rockers are clamped to eccentric shafts - loosen clamps, rotate shafts to get deisred lash, reclamp (careful with the torque).

Are there two springs closing valve - one inside the
other - that could somehow be broken/binding on each other?
no
When did engine last run right? Or has it been stored a long time?

History?
After decades of motorcycles,
in the mid 1960s, Honda made a 2 seater sports car, similar in appearance to British sports cars. "S600"/"S800", with some less common "S500" and even "S360" models, even a forward control pickup ("TN360"). Water cooled, with dual overhead cams, 4 carbs, roller crank, roller wrist pin bushings, 9.5K redline, etc. Some of the early ones had chain drives in trailing arms from the rear differential to the rear wheels.
"A design exercise that got out of hand and went into production". "A poor man's Ferrari"
Constant changes as they tinkered with the design.
Never officially imported into USA, but there are dozens brought over by individuals.


In 1969, they introduced a "tiny" car with modified motorcycle engine design, and mini-cooper like body. It is an air-cooled paraallel twin, with a motorcycle style crankcase, but with a differential at the rear of the crancase, and a reverse gear slapped onto the right side.
36HP. I showed one that was out of the car to a motorcycle salvage guy; he thought that it was some sort of Honda 3-wheeler that he hadn't seen before, and was shocked when I showed him that it came from a car.


N600 looks a little like a mini-cooper. The N360 is less common.
Some of the N360s and "Hawaiin" N600s did away with the heater, which was a clumsy piping to the side with a heat exchanger. The non-heater models were a cross flow head, with efficient routing ot the exhaust, and were available with a "sportier" cam for a claimed 45HP.
Oversized piston/cylinder sets were once available, and lowering kits.

Z600 is a "sportier" body, introduced in 1972. It is a hatchback, and the glass falls out of the rear hatch.


The air-cooled Honda 600s were replaced in 1973 by the Honda Civic, a water-cooled transverse 4 cylinder, similar to the VW Rabbit.

--
Grumpy Ol' Fred cisin@...


Bruce Dewing
 

My update for today:
Leak down tester came today.  Left side 77% and right side 80%.  Stethoscope was no help, can't hear the leak cause I'm getting old, can't hear bla bla bla.  Compression test Left 167 Right 0, then 25.
I'll cut to the chase here.  I suspect there is a head gasket leak, possibly a valve problem.  There are 4 inaccessible head nuts under the rockers next to the valve guide and another 4 (dome nuts) accessible in the cam box (torque already checked).  Looking at the reference engine (I have a few) It looks like the right nut intake side isn't down far enough.  Due to the cooling shrouds and the cooling fan, it's impossible to see the cylinder head to jug mating surface.
It's not my car, I'm helping a buddy out but this could turn out poorly.  I may take it as far as removing the rockers to check torque on the head nuts, but no further.

Bruce  
Grass Valley, Ca

On Wednesday, December 2, 2020, 11:08:38 AM PST, Fred Cisin <cisin@...> wrote:


On Wed, 2 Dec 2020, Ken Nelson wrote:
> Can you tell if the valves of that cyl are seating completely?  Is
> throttleplate being held completely open during test?

And, it's variable venturi.

> Is carb linkage working properly?
right up top, easy to hold the throttle open with your other hand.

> ls valve adjusting screw loose in its threads?  Is it
> pushrod or OHC driving the valve?  If operated by a rocker arm, is that
> part worn/loose/getting stuck?  lf pushrod-operated rocker, is pushrod
> bent/flopping around?

overhead cam, rockers are clamped to eccentric shafts - loosen clamps,
rotate shafts to get deisred lash, reclamp (careful with the torque).

> Are there two springs closing valve - one inside the
> other - that could somehow be broken/binding on each other?
no
> When did engine last run right?  Or has it been stored a long time?


> History?

After decades of motorcycles,
in the mid 1960s, Honda made a 2 seater sports car, similar in appearance
to British sports cars.  "S600"/"S800", with some less common "S500" and
even "S360" models, even a forward control pickup ("TN360").  Water
cooled, with dual overhead cams, 4 carbs, roller crank, roller wrist pin
bushings, 9.5K redline, etc.  Some of the early ones had chain drives in
trailing arms from the rear differential to the rear wheels.
"A design exercise that got out of hand and went into production".
"A poor man's Ferrari"
Constant changes as they tinkered with the design.
Never officially imported into USA, but there are dozens brought over by
individuals.


In 1969, they introduced a "tiny" car with modified motorcycle
engine design, and mini-cooper like body.  It is an air-cooled paraallel
twin, with a motorcycle style crankcase, but with a differential at the
rear of the crancase, and a reverse gear slapped onto the right side.
36HP.  I showed one that was out of the car to a motorcycle salvage guy;
he thought that it was some sort of Honda 3-wheeler that he hadn't seen
before, and was shocked when I showed him that it came from a car.


N600 looks a little like a mini-cooper.  The N360 is less common.
Some of the N360s and "Hawaiin" N600s did away with the heater, which was
a clumsy piping to the side with a heat exchanger.  The non-heater models
were a cross flow head, with efficient routing ot the exhaust, and were
available with a "sportier" cam for a claimed 45HP.
Oversized piston/cylinder sets were once available, and lowering kits.

Z600 is a "sportier" body, introduced in 1972.  It is a hatchback, and the
glass falls out of the rear hatch.


The air-cooled Honda 600s were replaced in 1973 by the Honda Civic, a
water-cooled transverse 4 cylinder, similar to the VW Rabbit.

--
Grumpy Ol' Fred            cisin@...






Ken Nelson
 

Air or water cooled?  I don't know those cars.  Variation like that seems very strange - how could it be so extremely variable - 0 to 25?  Are you spinning eng. with starter & watching each cyl pump up?  I don't follow - are cyls connected via same head gasket?  Or does each cyl have own separate gasket?  When you say first measurement gets zero psi, is that on first crank rotation, then pressure rises to 25 on next few spins?  Is this range consistent when stopped, & started again?  If so, sounds more like hole in piston - I can't imagine a leaky gasket reducing pressure to 25 psi, but rather a big hole somewhere or valve not seating all the way, 

Ken

On Wed, Dec 2, 2020 at 8:44 PM Bruce Dewing via groups.io <tralfaz42=yahoo.com@groups.io> wrote:
My update for today:
Leak down tester came today.  Left side 77% and right side 80%.  Stethoscope was no help, can't hear the leak cause I'm getting old, can't hear bla bla bla.  Compression test Left 167 Right 0, then 25.
I'll cut to the chase here.  I suspect there is a head gasket leak, possibly a valve problem.  There are 4 inaccessible head nuts under the rockers next to the valve guide and another 4 (dome nuts) accessible in the cam box (torque already checked).  Looking at the reference engine (I have a few) It looks like the right nut intake side isn't down far enough.  Due to the cooling shrouds and the cooling fan, it's impossible to see the cylinder head to jug mating surface.
It's not my car, I'm helping a buddy out but this could turn out poorly.  I may take it as far as removing the rockers to check torque on the head nuts, but no further.

Bruce  
Grass Valley, Ca

On Wednesday, December 2, 2020, 11:08:38 AM PST, Fred Cisin <cisin@...> wrote:


On Wed, 2 Dec 2020, Ken Nelson wrote:
> Can you tell if the valves of that cyl are seating completely?  Is
> throttleplate being held completely open during test?

And, it's variable venturi.

> Is carb linkage working properly?
right up top, easy to hold the throttle open with your other hand.

> ls valve adjusting screw loose in its threads?  Is it
> pushrod or OHC driving the valve?  If operated by a rocker arm, is that
> part worn/loose/getting stuck?  lf pushrod-operated rocker, is pushrod
> bent/flopping around?

overhead cam, rockers are clamped to eccentric shafts - loosen clamps,
rotate shafts to get deisred lash, reclamp (careful with the torque).

> Are there two springs closing valve - one inside the
> other - that could somehow be broken/binding on each other?
no
> When did engine last run right?  Or has it been stored a long time?


> History?

After decades of motorcycles,
in the mid 1960s, Honda made a 2 seater sports car, similar in appearance
to British sports cars.  "S600"/"S800", with some less common "S500" and
even "S360" models, even a forward control pickup ("TN360").  Water
cooled, with dual overhead cams, 4 carbs, roller crank, roller wrist pin
bushings, 9.5K redline, etc.  Some of the early ones had chain drives in
trailing arms from the rear differential to the rear wheels.
"A design exercise that got out of hand and went into production".
"A poor man's Ferrari"
Constant changes as they tinkered with the design.
Never officially imported into USA, but there are dozens brought over by
individuals.


In 1969, they introduced a "tiny" car with modified motorcycle
engine design, and mini-cooper like body.  It is an air-cooled paraallel
twin, with a motorcycle style crankcase, but with a differential at the
rear of the crancase, and a reverse gear slapped onto the right side.
36HP.  I showed one that was out of the car to a motorcycle salvage guy;
he thought that it was some sort of Honda 3-wheeler that he hadn't seen
before, and was shocked when I showed him that it came from a car.


N600 looks a little like a mini-cooper.  The N360 is less common.
Some of the N360s and "Hawaiin" N600s did away with the heater, which was
a clumsy piping to the side with a heat exchanger.  The non-heater models
were a cross flow head, with efficient routing ot the exhaust, and were
available with a "sportier" cam for a claimed 45HP.
Oversized piston/cylinder sets were once available, and lowering kits.

Z600 is a "sportier" body, introduced in 1972.  It is a hatchback, and the
glass falls out of the rear hatch.


The air-cooled Honda 600s were replaced in 1973 by the Honda Civic, a
water-cooled transverse 4 cylinder, similar to the VW Rabbit.

--
Grumpy Ol' Fred            cisin@...






Bruce Dewing
 

Air cooled.  Separate tests about 6 seconds, watching gauge.  One head gasket.  Video camera useless, it flops around in cylinder like limp spaghetti. 

Bruce

On Wednesday, December 2, 2020, 9:07:13 PM PST, Ken Nelson <citbuff@...> wrote:


Air or water cooled?  I don't know those cars.  Variation like that seems very strange - how could it be so extremely variable - 0 to 25?  Are you spinning eng. with starter & watching each cyl pump up?  I don't follow - are cyls connected via same head gasket?  Or does each cyl have own separate gasket?  When you say first measurement gets zero psi, is that on first crank rotation, then pressure rises to 25 on next few spins?  Is this range consistent when stopped, & started again?  If so, sounds more like hole in piston - I can't imagine a leaky gasket reducing pressure to 25 psi, but rather a big hole somewhere or valve not seating all the way, 

Ken

On Wed, Dec 2, 2020 at 8:44 PM Bruce Dewing via groups.io <tralfaz42=yahoo.com@groups.io> wrote:
My update for today:
Leak down tester came today.  Left side 77% and right side 80%.  Stethoscope was no help, can't hear the leak cause I'm getting old, can't hear bla bla bla.  Compression test Left 167 Right 0, then 25.
I'll cut to the chase here.  I suspect there is a head gasket leak, possibly a valve problem.  There are 4 inaccessible head nuts under the rockers next to the valve guide and another 4 (dome nuts) accessible in the cam box (torque already checked).  Looking at the reference engine (I have a few) It looks like the right nut intake side isn't down far enough.  Due to the cooling shrouds and the cooling fan, it's impossible to see the cylinder head to jug mating surface.
It's not my car, I'm helping a buddy out but this could turn out poorly.  I may take it as far as removing the rockers to check torque on the head nuts, but no further.

Bruce  
Grass Valley, Ca

On Wednesday, December 2, 2020, 11:08:38 AM PST, Fred Cisin <cisin@...> wrote:


On Wed, 2 Dec 2020, Ken Nelson wrote:
> Can you tell if the valves of that cyl are seating completely?  Is
> throttleplate being held completely open during test?

And, it's variable venturi.

> Is carb linkage working properly?
right up top, easy to hold the throttle open with your other hand.

> ls valve adjusting screw loose in its threads?  Is it
> pushrod or OHC driving the valve?  If operated by a rocker arm, is that
> part worn/loose/getting stuck?  lf pushrod-operated rocker, is pushrod
> bent/flopping around?

overhead cam, rockers are clamped to eccentric shafts - loosen clamps,
rotate shafts to get deisred lash, reclamp (careful with the torque).

> Are there two springs closing valve - one inside the
> other - that could somehow be broken/binding on each other?
no
> When did engine last run right?  Or has it been stored a long time?


> History?

After decades of motorcycles,
in the mid 1960s, Honda made a 2 seater sports car, similar in appearance
to British sports cars.  "S600"/"S800", with some less common "S500" and
even "S360" models, even a forward control pickup ("TN360").  Water
cooled, with dual overhead cams, 4 carbs, roller crank, roller wrist pin
bushings, 9.5K redline, etc.  Some of the early ones had chain drives in
trailing arms from the rear differential to the rear wheels.
"A design exercise that got out of hand and went into production".
"A poor man's Ferrari"
Constant changes as they tinkered with the design.
Never officially imported into USA, but there are dozens brought over by
individuals.


In 1969, they introduced a "tiny" car with modified motorcycle
engine design, and mini-cooper like body.  It is an air-cooled paraallel
twin, with a motorcycle style crankcase, but with a differential at the
rear of the crancase, and a reverse gear slapped onto the right side.
36HP.  I showed one that was out of the car to a motorcycle salvage guy;
he thought that it was some sort of Honda 3-wheeler that he hadn't seen
before, and was shocked when I showed him that it came from a car.


N600 looks a little like a mini-cooper.  The N360 is less common.
Some of the N360s and "Hawaiin" N600s did away with the heater, which was
a clumsy piping to the side with a heat exchanger.  The non-heater models
were a cross flow head, with efficient routing ot the exhaust, and were
available with a "sportier" cam for a claimed 45HP.
Oversized piston/cylinder sets were once available, and lowering kits.

Z600 is a "sportier" body, introduced in 1972.  It is a hatchback, and the
glass falls out of the rear hatch.


The air-cooled Honda 600s were replaced in 1973 by the Honda Civic, a
water-cooled transverse 4 cylinder, similar to the VW Rabbit.

--
Grumpy Ol' Fred            cisin@...






Ken Nelson
 

Very strange, but there's got to be an explanation - wish I could watch the whole process - 

Ken

On Thu, Dec 3, 2020 at 12:19 AM Bruce Dewing via groups.io <tralfaz42=yahoo.com@groups.io> wrote:
Air cooled.  Separate tests about 6 seconds, watching gauge.  One head gasket.  Video camera useless, it flops around in cylinder like limp spaghetti. 

Bruce

On Wednesday, December 2, 2020, 9:07:13 PM PST, Ken Nelson <citbuff@...> wrote:


Air or water cooled?  I don't know those cars.  Variation like that seems very strange - how could it be so extremely variable - 0 to 25?  Are you spinning eng. with starter & watching each cyl pump up?  I don't follow - are cyls connected via same head gasket?  Or does each cyl have own separate gasket?  When you say first measurement gets zero psi, is that on first crank rotation, then pressure rises to 25 on next few spins?  Is this range consistent when stopped, & started again?  If so, sounds more like hole in piston - I can't imagine a leaky gasket reducing pressure to 25 psi, but rather a big hole somewhere or valve not seating all the way, 

Ken

On Wed, Dec 2, 2020 at 8:44 PM Bruce Dewing via groups.io <tralfaz42=yahoo.com@groups.io> wrote:
My update for today:
Leak down tester came today.  Left side 77% and right side 80%.  Stethoscope was no help, can't hear the leak cause I'm getting old, can't hear bla bla bla.  Compression test Left 167 Right 0, then 25.
I'll cut to the chase here.  I suspect there is a head gasket leak, possibly a valve problem.  There are 4 inaccessible head nuts under the rockers next to the valve guide and another 4 (dome nuts) accessible in the cam box (torque already checked).  Looking at the reference engine (I have a few) It looks like the right nut intake side isn't down far enough.  Due to the cooling shrouds and the cooling fan, it's impossible to see the cylinder head to jug mating surface.
It's not my car, I'm helping a buddy out but this could turn out poorly.  I may take it as far as removing the rockers to check torque on the head nuts, but no further.

Bruce  
Grass Valley, Ca

On Wednesday, December 2, 2020, 11:08:38 AM PST, Fred Cisin <cisin@...> wrote:


On Wed, 2 Dec 2020, Ken Nelson wrote:
> Can you tell if the valves of that cyl are seating completely?  Is
> throttleplate being held completely open during test?

And, it's variable venturi.

> Is carb linkage working properly?
right up top, easy to hold the throttle open with your other hand.

> ls valve adjusting screw loose in its threads?  Is it
> pushrod or OHC driving the valve?  If operated by a rocker arm, is that
> part worn/loose/getting stuck?  lf pushrod-operated rocker, is pushrod
> bent/flopping around?

overhead cam, rockers are clamped to eccentric shafts - loosen clamps,
rotate shafts to get deisred lash, reclamp (careful with the torque).

> Are there two springs closing valve - one inside the
> other - that could somehow be broken/binding on each other?
no
> When did engine last run right?  Or has it been stored a long time?


> History?

After decades of motorcycles,
in the mid 1960s, Honda made a 2 seater sports car, similar in appearance
to British sports cars.  "S600"/"S800", with some less common "S500" and
even "S360" models, even a forward control pickup ("TN360").  Water
cooled, with dual overhead cams, 4 carbs, roller crank, roller wrist pin
bushings, 9.5K redline, etc.  Some of the early ones had chain drives in
trailing arms from the rear differential to the rear wheels.
"A design exercise that got out of hand and went into production".
"A poor man's Ferrari"
Constant changes as they tinkered with the design.
Never officially imported into USA, but there are dozens brought over by
individuals.


In 1969, they introduced a "tiny" car with modified motorcycle
engine design, and mini-cooper like body.  It is an air-cooled paraallel
twin, with a motorcycle style crankcase, but with a differential at the
rear of the crancase, and a reverse gear slapped onto the right side.
36HP.  I showed one that was out of the car to a motorcycle salvage guy;
he thought that it was some sort of Honda 3-wheeler that he hadn't seen
before, and was shocked when I showed him that it came from a car.


N600 looks a little like a mini-cooper.  The N360 is less common.
Some of the N360s and "Hawaiin" N600s did away with the heater, which was
a clumsy piping to the side with a heat exchanger.  The non-heater models
were a cross flow head, with efficient routing ot the exhaust, and were
available with a "sportier" cam for a claimed 45HP.
Oversized piston/cylinder sets were once available, and lowering kits.

Z600 is a "sportier" body, introduced in 1972.  It is a hatchback, and the
glass falls out of the rear hatch.


The air-cooled Honda 600s were replaced in 1973 by the Honda Civic, a
water-cooled transverse 4 cylinder, similar to the VW Rabbit.

--
Grumpy Ol' Fred            cisin@...






oddrodstjets <oddrods@...>
 

If I remember correctly the cam chain tensioner is known to fail and is very difficult to replace.




On Wednesday, December 2, 2020 Ken Nelson <ArcaneAutos@groups.io> wrote:

Very strange, but there's got to be an explanation - wish I could watch the whole process - 

Ken

On Thu, Dec 3, 2020 at 12:19 AM Bruce Dewing via groups.io <tralfaz42=yahoo.com@groups.io> wrote:
Air cooled.  Separate tests about 6 seconds, watching gauge.  One head gasket.  Video camera useless, it flops around in cylinder like limp spaghetti. 

Bruce

On Wednesday, December 2, 2020, 9:07:13 PM PST, Ken Nelson <citbuff@...> wrote:


Air or water cooled?  I don't know those cars.  Variation like that seems very strange - how could it be so extremely variable - 0 to 25?  Are you spinning eng. with starter & watching each cyl pump up?  I don't follow - are cyls connected via same head gasket?  Or does each cyl have own separate gasket?  When you say first measurement gets zero psi, is that on first crank rotation, then pressure rises to 25 on next few spins?  Is this range consistent when stopped, & started again?  If so, sounds more like hole in piston - I can't imagine a leaky gasket reducing pressure to 25 psi, but rather a big hole somewhere or valve not seating all the way, 

Ken

On Wed, Dec 2, 2020 at 8:44 PM Bruce Dewing via groups.io <tralfaz42=yahoo.com@groups.io> wrote:
My update for today:
Leak down tester came today.  Left side 77% and right side 80%.  Stethoscope was no help, can't hear the leak cause I'm getting old, can't hear bla bla bla.  Compression test Left 167 Right 0, then 25.
I'll cut to the chase here.  I suspect there is a head gasket leak, possibly a valve problem.  There are 4 inaccessible head nuts under the rockers next to the valve guide and another 4 (dome nuts) accessible in the cam box (torque already checked).  Looking at the reference engine (I have a few) It looks like the right nut intake side isn't down far enough.  Due to the cooling shrouds and the cooling fan, it's impossible to see the cylinder head to jug mating surface.
It's not my car, I'm helping a buddy out but this could turn out poorly.  I may take it as far as removing the rockers to check torque on the head nuts, but no further.

Bruce  
Grass Valley, Ca

On Wednesday, December 2, 2020, 11:08:38 AM PST, Fred Cisin <cisin@...> wrote:


On Wed, 2 Dec 2020, Ken Nelson wrote:
> Can you tell if the valves of that cyl are seating completely?  Is
> throttleplate being held completely open during test?

And, it's variable venturi.

> Is carb linkage working properly?
right up top, easy to hold the throttle open with your other hand.

> ls valve adjusting screw loose in its threads?  Is it
> pushrod or OHC driving the valve?  If operated by a rocker arm, is that
> part worn/loose/getting stuck?  lf pushrod-operated rocker, is pushrod
> bent/flopping around?

overhead cam, rockers are clamped to eccentric shafts - loosen clamps,
rotate shafts to get deisred lash, reclamp (careful with the torque).

> Are there two springs closing valve - one inside the
> other - that could somehow be broken/binding on each other?
no
> When did engine last run right?  Or has it been stored a long time?


> History?

After decades of motorcycles,
in the mid 1960s, Honda made a 2 seater sports car, similar in appearance
to British sports cars.  "S600"/"S800", with some less common "S500" and
even "S360" models, even a forward control pickup ("TN360").  Water
cooled, with dual overhead cams, 4 carbs, roller crank, roller wrist pin
bushings, 9.5K redline, etc.  Some of the early ones had chain drives in
trailing arms from the rear differential to the rear wheels.
"A design exercise that got out of hand and went into production".
"A poor man's Ferrari"
Constant changes as they tinkered with the design.
Never officially imported into USA, but there are dozens brought over by
individuals.


In 1969, they introduced a "tiny" car with modified motorcycle
engine design, and mini-cooper like body.  It is an air-cooled paraallel
twin, with a motorcycle style crankcase, but with a differential at the
rear of the crancase, and a reverse gear slapped onto the right side.
36HP.  I showed one that was out of the car to a motorcycle salvage guy;
he thought that it was some sort of Honda 3-wheeler that he hadn't seen
before, and was shocked when I showed him that it came from a car.


N600 looks a little like a mini-cooper.  The N360 is less common.
Some of the N360s and "Hawaiin" N600s did away with the heater, which was
a clumsy piping to the side with a heat exchanger.  The non-heater models
were a cross flow head, with efficient routing ot the exhaust, and were
available with a "sportier" cam for a claimed 45HP.
Oversized piston/cylinder sets were once available, and lowering kits.

Z600 is a "sportier" body, introduced in 1972.  It is a hatchback, and the
glass falls out of the rear hatch.


The air-cooled Honda 600s were replaced in 1973 by the Honda Civic, a
water-cooled transverse 4 cylinder, similar to the VW Rabbit.

--
Grumpy Ol' Fred            cisin@...






Bruce Dewing
 

It is because it's underneath the jugs and pulling the top end is such a PITA.  Not an issue here as the chain stretch test passed.

Bruce

On Wednesday, December 2, 2020, 11:09:26 PM PST, oddrodstjets via groups.io <oddrods@...> wrote:


If I remember correctly the cam chain tensioner is known to fail and is very difficult to replace.


On Wednesday, December 2, 2020 Ken Nelson <ArcaneAutos@groups.io> wrote:
Very strange, but there's got to be an explanation - wish I could watch the whole process - 

Ken

On Thu, Dec 3, 2020 at 12:19 AM Bruce Dewing via groups.io <tralfaz42=yahoo.com@groups.io> wrote:
Air cooled.  Separate tests about 6 seconds, watching gauge.  One head gasket.  Video camera useless, it flops around in cylinder like limp spaghetti. 

Bruce

On Wednesday, December 2, 2020, 9:07:13 PM PST, Ken Nelson <citbuff@...> wrote:


Air or water cooled?  I don't know those cars.  Variation like that seems very strange - how could it be so extremely variable - 0 to 25?  Are you spinning eng. with starter & watching each cyl pump up?  I don't follow - are cyls connected via same head gasket?  Or does each cyl have own separate gasket?  When you say first measurement gets zero psi, is that on first crank rotation, then pressure rises to 25 on next few spins?  Is this range consistent when stopped, & started again?  If so, sounds more like hole in piston - I can't imagine a leaky gasket reducing pressure to 25 psi, but rather a big hole somewhere or valve not seating all the way, 

Ken

On Wed, Dec 2, 2020 at 8:44 PM Bruce Dewing via groups.io <tralfaz42=yahoo.com@groups.io> wrote:
My update for today:
Leak down tester came today.  Left side 77% and right side 80%.  Stethoscope was no help, can't hear the leak cause I'm getting old, can't hear bla bla bla.  Compression test Left 167 Right 0, then 25.
I'll cut to the chase here.  I suspect there is a head gasket leak, possibly a valve problem.  There are 4 inaccessible head nuts under the rockers next to the valve guide and another 4 (dome nuts) accessible in the cam box (torque already checked).  Looking at the reference engine (I have a few) It looks like the right nut intake side isn't down far enough.  Due to the cooling shrouds and the cooling fan, it's impossible to see the cylinder head to jug mating surface.
It's not my car, I'm helping a buddy out but this could turn out poorly.  I may take it as far as removing the rockers to check torque on the head nuts, but no further.

Bruce  
Grass Valley, Ca

On Wednesday, December 2, 2020, 11:08:38 AM PST, Fred Cisin <cisin@...> wrote:


On Wed, 2 Dec 2020, Ken Nelson wrote:
> Can you tell if the valves of that cyl are seating completely?  Is
> throttleplate being held completely open during test?

And, it's variable venturi.

> Is carb linkage working properly?
right up top, easy to hold the throttle open with your other hand.

> ls valve adjusting screw loose in its threads?  Is it
> pushrod or OHC driving the valve?  If operated by a rocker arm, is that
> part worn/loose/getting stuck?  lf pushrod-operated rocker, is pushrod
> bent/flopping around?

overhead cam, rockers are clamped to eccentric shafts - loosen clamps,
rotate shafts to get deisred lash, reclamp (careful with the torque).

> Are there two springs closing valve - one inside the
> other - that could somehow be broken/binding on each other?
no
> When did engine last run right?  Or has it been stored a long time?


> History?

After decades of motorcycles,
in the mid 1960s, Honda made a 2 seater sports car, similar in appearance
to British sports cars.  "S600"/"S800", with some less common "S500" and
even "S360" models, even a forward control pickup ("TN360").  Water
cooled, with dual overhead cams, 4 carbs, roller crank, roller wrist pin
bushings, 9.5K redline, etc.  Some of the early ones had chain drives in
trailing arms from the rear differential to the rear wheels.
"A design exercise that got out of hand and went into production".
"A poor man's Ferrari"
Constant changes as they tinkered with the design.
Never officially imported into USA, but there are dozens brought over by
individuals.


In 1969, they introduced a "tiny" car with modified motorcycle
engine design, and mini-cooper like body.  It is an air-cooled paraallel
twin, with a motorcycle style crankcase, but with a differential at the
rear of the crancase, and a reverse gear slapped onto the right side.
36HP.  I showed one that was out of the car to a motorcycle salvage guy;
he thought that it was some sort of Honda 3-wheeler that he hadn't seen
before, and was shocked when I showed him that it came from a car.


N600 looks a little like a mini-cooper.  The N360 is less common.
Some of the N360s and "Hawaiin" N600s did away with the heater, which was
a clumsy piping to the side with a heat exchanger.  The non-heater models
were a cross flow head, with efficient routing ot the exhaust, and were
available with a "sportier" cam for a claimed 45HP.
Oversized piston/cylinder sets were once available, and lowering kits.

Z600 is a "sportier" body, introduced in 1972.  It is a hatchback, and the
glass falls out of the rear hatch.


The air-cooled Honda 600s were replaced in 1973 by the Honda Civic, a
water-cooled transverse 4 cylinder, similar to the VW Rabbit.

--
Grumpy Ol' Fred            cisin@...






Fred Cisin
 

WORSE!
MUCH WORSE!

For those not familiar with those cars:
The design is absolutely, totally, a Honda parallel twin motorcycle.
The differential was designed in (as if it were going to be for a three-wheeler); the reverse gear is an addition to the side, and looks like an afterthought.

With the jugs out, you can replace the slipper guide (with a little extra work repairing the dowel pin slots), but not the tensioner. And, an opportunity to repair all of the broken 6mmx1.0 screwholes in the top end.

The pivot of the swinging arm of the cam chain tensioner roller is down in the crankcase, and it is not designed to separate the roller from the arm. You have to "split the case" (same as engine overhaul or transmission) to undo the swinging arm to put in a new one. "Pulling the top end" is nothing (done in the car) compared to splitting the case (drop the subframe to pull the engine out, and then it is usual motorcycle bottom end job.)
SOME people have tried, with varying levels of problems, to detach the roller from its swinging arm and put a new roller from a new one on.


That is one more reason why it is very important that you did the right thing and checked the cam chain and cam timing and found that it was tight and had not slipped a tooth in the chain. The teeth of the cam gear are probably worn, but you can usually get away with that.

--
Grumpy Ol' Fred cisin@...

On Thu, 3 Dec 2020, Bruce Dewing via groups.io wrote:

It is because it's underneath the jugs and pulling the top end is such a PITA.  Not an issue here as the chain stretch test passed.
Bruce

On Wednesday, December 2, 2020, 11:09:26 PM PST, oddrodstjets via groups.io <oddrods@...> wrote:


If I remember correctly the cam chain tensioner is known to fail and is very difficult to replace.


600miles
 

I had a customer when I lived in Boulder Creek who owned my moms old Honda 600 sedan. Jenny didn't understand redline meant slow down. I had to change her crankshaft at least 3 times while she had it. I got it down to a 10 hour project where she hung out all day. I would cut the master link and remove the whole top end assembled - Jugs to cam box came off as 1 unit so I only ever had to replace the cylinder base gasket.