Ossa Pistons

[Tony T]

Just a little word for something to watch out for.
I just bought a 0.020" OS piston from Keith Lynas at Ossa Planet and my machine shop sent it back saying it was actually only 0.008" OS.
I had another tech double check the measurments and it's right.
I've let Keith know, but haven't heard back from him as yet.
This is definitely not Keith's fault and I always get excellent service from him, but it looks like the manufacturer is a bit confused. 
0.008" is actually 0.203mm, so I wonder if that's where they're getting mixed up?

More details as they come to hand.

[Tony T]

Just heard back from Keith, and he says the piston is meant to be 0.008" or 0.20mm OS. Unfortunately, it is very clearly marked +0.020"
I think I'll have to send him a photo cos he doesn't believe me, my machining shop or my mechanic. 

[09.0]

I hit a snag with my piston kit also. The original tarabusi runs rings that have a big end gap. This is due to the locating pegs being big and are part of the end gap. The new ( Taiwanese I think) pistons that are used have a modern style locator but the rings are the old style so the end gap is too big. So the guy doing my rebore who picked this up sourced another set of rings through Serco . I told the guy I got them off this but he said he's never had a problem before. A bike would still run ok but not to its potential with all that blow by.

[euro bikes]

I had trouble with the rings sticking in the groove's and had no compression, had to file them out a bit, that fixed it

[Tony T]

FWIW Here's the marking on top of my piston which is  +.20mm

[TT5 Matt]

that seeze 20 thou in my book and thats what my old tafe teacher would say if i showed it to him