I understand the need to match the NSR 250 cylinder marking with the correct piston:
A barrel =B piston
B barrel= no mark
C barrel =D piston.

But what is the difference? Is it just piston/cylinder diameter? Why the differences; why not have just one cylinder/piston combination?

ive thought of this as well !
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When Honda made the barrels they measured them and stamped the different sizes a or c. Some poor sod had to measure pistons which were also stamped to denote the actual size because they could make them all the correct size

I think that's what happened

Anyway the chance a barrel stamp still corresponds to the size is highly unlikely as it's probably worn or been replated.

The best solution is buying pistons then getting the barrel replated to match those new pistons rather than a replate then trying to get pistons to match

Don't forget this is 25 year old production techniques and Hondas crafty way of getting around the inaccuracies

I disagree, mellorp.

Basic problem of any manufacturing process is that you cannot avoid certain tolerances. There are tolerances caused by systematic effects as well as random effects.
Honda specifies a very small piston-to-cylinder gap. This is only possible if you classify the machined partscylinders and pistons and then use combinations that deliver the small gap you want.
I am sure that re. machining precision not a lot has changed within the last 20 years. Less precision and selecting combinations is cheaper in the end.

Piston/cylinder - which is matched to which?
You can't match a piston to a cylinder. Pistons are oval, tapered and who knows what else. A cylinder is 100% round and cylindrical.The old plating is removed, bore measured, thickness of new plating minus honing is considered and matched to one of the available piston sizes.

So what does anybody think of non genuine pistons.
Mitaka pistons are sold as one size fits all nsr250s.
Do you think to fit these is an absolute no go?
I for one are very tempted due to cost and I have read that some people say quality is very good.

Daz
_________________
stink wheels forever.

dazsegger wrote:
So what does anybody think of non genuine pistons.
Mitaka pistons are sold as one size fits all nsr250s.

Performance Engineering

You get what you pay for.
_________________
Andy.
NSR-WORLD.COM

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