Reply To: 1955 RD17

[Mumbles]

grunt311 wrote:

The cylinder walls are glass smooth

If they are mirror smooth, that’s just a sign of being well used over the years. Cylinder walls will usually show a bit of the factory honing, or cross hatch, even after multi years of use but if they are that smooth, it indicates some wear going on. How’s the lip at the top of the cylinder? Can you catch your fingernail on it?  If you have a bore gauge handy, you can measure the taper of the cylinders to get an idea of the amount of wear without having to remove the powerhead.

If the cross hatch is worn away, the rings are probably worn an equal amount. Re-ringing the motor wont repair the worn cylinders and will probably result in lower compression than what the motor has now as they wont seat properly into the worn cylinders, which are probably egg shaped by now.

So if the cylinder walls and pistons don’t show any signs of  damage, it might be best to reinstall the head with a new gasket and call it a day, otherwise you’re looking at a major teardown and possibly having to get the block bored to fit new oversize pistons and rings, if you can find them.

Richening the fuel mix from 24:1 to 16:1 might also help the motor to last longer. If the planets are aligned properly, your motor might have gotten lucky enough to survive the overheat without suffering any damage and the tightness would only have been temporary until it cooled down.