Broken valve spring?

[Steve]

Anyway I'm a bit confused about measuring the piston ring end gap once the rings are re-installed.

The only proper way to measure the end gap that I know of is to place the ring in the cylinder, push it with the piston to make sure it's squarely installed, measure the gap. Since it's hard to use the pistons that are mounted to the crank to to this, maybe use a spray can that is about the same size or use a try-square to push the ring down the same distance at several places around its perimeter.

I would presume that for an oversize piston, the end gap would be pretty close to the same as for stock.

Any measurements concerning the side clearances on the rings would have to be discussed with the piston manufacturer.

.

[Big Jay]

Just curious what would cause a bent valve? I plan to change the valve seals while I have the top end out but what else should I look at?

Usually a bent exhaust valve comes from over reving ( missed shift ) etc. The piston is chasing the exhaust valve home on the exhaust stroke. If the valve hesitates ( floats ), the piston will catch it.

This is why you always have more PTV on the exhaust side when building an engine.

[razooki]

OK, so far I have measured everything (piston diameter, ring gaps, ring grooves) except for the cylinder bore since I do not have a dial bore gauge. Everything is within spec. The question is if the cylinder bores are also OK, can I just re-assemble everything or should I deglaze the cylinders before installing everything?

[razooki]

Anyone? Anyone?

[doctorgonzo]

Probably lots of opinions on this, but I wouldn't get that far down in the engine without honing and putting in new rings. Probably cost about $50 to have a shop hone them (or to buy a hone), and $90 for new rings. It would suck so bad to tear it down that far, put it all back together, and then have marginal compression.

[razooki]

Probably lots of opinions on this, but I wouldn't get that far down in the engine without honing and putting in new rings. Probably cost about $50 to have a shop hone them (or to buy a hone), and $90 for new rings. It would suck so bad to tear it down that far, put it all back together, and then have marginal compression.

Normally I would agree but the purpose of my tearing it down was to inspect it. If everything is within spec as per the manual I don't see why I would need to replace the rings (about $200). I am pretty sure the pistons are 1mm over since the rings have an 'N' stamped on them so honing is out of the question.

[Nessism]

OS pistons will be stamped appropriately on top, and that N just denotes which ring it is and which side goes up I think.

Doc is right about the rings cost assuming they are STD size. I'd replace them. If you don't want to, just stick the engine back together. There is some controversy about the necessity of honing if you are going to reuse the old rings and I'm in the camp that doesn't hone.

[mac65]

I did not hone my 750 it is fine, use your best judgement