N6 Compression

Fred Cisin

Check with miles for parts!
600miles <z600miles@comcast.net>

If you turn the engine by hand, you can watch the valves open and close. (overhead cam with rockers). When valves are closed, there should be about 0.006" valve lash. (like a VW)

Get some 6mmx1.0 nutserts. You're gonna need them. Helicoils will do, but don't hold up as well.

Get some very small left handed drill bits. And a TINY cold chisel. And
whatever other broken screw extracters you like.

Starting with: the valve cover is held on with 4 "special" 6mm bolts with 12mm heads. That means that they have been overtightened every time that anybody other than Miles or I have worked on it. If you have convenient access to a small lathe and some delrin, you could make some stepped sleeves to use regular bolts; try a washer with Phillips head or socket head caap screws - then people won't ovetighten them.

In back of the cylinders, the fan is held on by 4 long 6mm bolts. Check them, they are probably broken.

On top, the early carburetor is topped by an almost flat slightly domed piece of sheet metal that covers the diaphragm. The diaphragm is likely to be ripped. Later ones had a cast cylindrical top cover, and no diaphragm to rip.

on the left side, betwen the clutch and the transmission is the primary drive assembly. Early ones had round fubber dampers. Later ones were trapezoidal. Replace the early assembly with the later one.

looking down alng the cam chain, . . .
between the cylinders is a rubber covered slipper guide. It's probably a bit worn. It is held in place by a dowel pin laying n a groove in the top of the cylinders (under the head), and another dowl pin at the bottom. The upper dowel pin slot is probably wobbled out. You can try to fill those, or mill a longer slot.

Down below the cylinders, there is a rubber covered roller for chain tension. It's worn out. But, the pivot for it is down inside the crankcase. Some have tried to drill out the mounting of it to the swing arm, to replace it.

Grumpy Ol' Fred cisin@xenosoft.com
600 guru 1972 through 1980 (almost 40 years since I worked on them)

On -1 xxx -1, 600miles wrote:
600guru since 1981


You need at least 110psi to run a honda 600. 160 is new rebuild spec. 150 is normal. Maybe your gauge is bad. I made a leak down set with an air compressor regulator and a hose from my compression tester. Dont forget to brace the crank with 17 or 22mm wrench and if doing a leak down might loosen all valves more than normal.

Some N6 have the valve seat issue where it pounds into the head and you can never keep an adjustment.


600guru since 1981

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