Jim,

They ARE jewels but I'm wondering about the fits that came out in the last number of years. Decade? I'll take a brand new engine or piston and cylinder set and run it in with a tank or so a tad rich then peak it out with no problems. This shows that not much break in is required due to a light fit. However, in my opinion, it's been TOO light. Evidence of that is that after extensive running, the piston shows signs of staining on the sidewalls of the piston. This indicates a lot of blowby.

The precision is there because you can swap out any piston to any cylinder and the same situation occurs. I'd kind of prefer the reverse so that you could mix and match the P and C to get a just right tightness that you could carefully break in for a perfect fit, best power and long life.

Elsewhere is mentioned that all the Cox machinery has been sent to China. Can anyone confirm this? I sure hope they do their homework and give us fits that require a break in.