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https://www.wemoto.com/bikes/honda/pa_50_camino/82/picture/piston_kit_0.00_standard
2 rings looks the same width. In one groove the ring is loose and the other ring it's not fitting freely (I haven't tried force yet). What's the third very thin octagonal ring for and where does it go?
its an expander ring. goes behind one of the other rings usually the lower on. rings should move freely in the slots with no significant up and down movement - you should be able to find specs
What bike?
PA50 Camino 1982
It looks like we have a duff kit. Neither ring will fit into the top groove even with a fair amount to force.
ssomethings wrong then for sure. rings should be a nice snug sliding fit. New rings on old piston? sure the ring grooves are not damaged?
Compete new kit (piston & rings) as photo above.
If the rings don’t fit, you may have to file the ends until they do.
its they wont fit in the grooves on the piston not they are too big for the bore
The 3rd ring is an expander.
Is the top ring and groove shaped so it only fits one way up?
If the rings don’t fit, you may have to file the ends until they do.
Needs to be a bit more precise than that, there should be a tolerance given either with the kit or in the bikes manual, put the ring in the cylinder and measure the gap with a feeler. If it's too big you need a new ring, if it's too small remove material with a very fine Emery board.
The idea is it closes up as the engine warms up so you don't want a large gap or you'll lose power, and you don't want it tight or it will buckle and fail when the engines hot.
It looks like the upper groove is a tad too narrow. I'll get them to post us another set.
@tinas, yep, i had to do it on the centre cylinder on my gt380.
It was a while ago, but iirc the tolerance was in the haynes manual.
Now that I think about it, it would have been summer of 2000.
Basic q but you are orienting the gaps them with the notches in the piston 180 out other wise the ring will not seat in the groove all the way round pretty much .......
Don't ask how I know this.....*
*Rs125 rebuild due to failed oil pump seals .......
The upper groove on the piston is for some reason narrower than the lower one. The 2 rings are the same width. The rings fit nicely into the lower groove but not at all into the upper one (we tried both rings). I suspect a manufacturing fault.
Just annoying as the engine is in bits and we'd like to get it sorted.