Re: I got the no/low compression blues

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 <> wrote:

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


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


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, 


On Wed, Dec 2, 2020 at 8:44 PM Bruce Dewing via <> 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.

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?
> 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

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@...

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