dave948, I agree that end gap is nothing more than a specification to be adjusted, no differant than setting valves on a 4t except that you only adjust ring gap once. The last bike that I rebuilt I put a B piston (Athena) in my A cylinder and did have to file the rings to meet the GG specs. I don't remember what I started with or ended up at. But...
widebear, you confirmed what I had written in my notes from college in '83 (damn I'm getting old). Automotive industry at that time used .004" min, .010" max. If I had had the info from dave948 I would have used it and probably filed the rings but as it is the A piston from Vertex had .015" gap (.381mm) and that is what I went with. (in a B cylinder rebuilt to A specs by Millenium)
The information that came with the Vertex piston only has specs for piston to cylinder tolerance (.002" - .0025" for anyone that is interested). No ring gap info.
Also, with all the automotive engines I have rebuilt I have never had to file a ring, I think the tolerances are much tighter in the high performance world of single cylinder engines.
Thanks to both of you for the info.
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jeff
'00 XC250 (mine)
LTS front and rear suspension, power valve cover, carb jet kit and rear chain glide, RB Designs head mod, BRP tall triple clamp, backyard foot-peg lowering conversion.
'04 EC250 (the kids)
(he can do his own mods haha!)
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