Hello, I have been riding a trials bike for about a year and really enjoying it, probably more as a trail rider. It is a lot of fun to pick my way up the technical stuff and a slow pace (get to see a lot more than blasting up on an enduro). Things do loosen up on my bike so consistent maintenance is a must when using the bike as a trail bike.

Last year, I picked up a refurbished cylinder from my dealer (bore of 76.00-76.01 mm) and bought a Wossner forged "A" piston (75.97 mm). Just found some generic instructions from Wossner suggesting about .012" for the top ring and about .015" for the second ring end gap when using their formulas. Those numbers seem high. Can anyone confirm good ring end gaps (either in mm or inches)? I was thinking around .008" or .2 mm would be about right. Thank you.

Jon

Usual is about 0.1 to 0.12 mm per 25 mm of bore.

I would expect the top ring to have slightly more gap than bottom ring as the top ring gets hotter and expands more

I've heard differing opinions on this... Anything from 0.009" to 0.015". However the brand new rings for my 300 already had 0.011" end gap so I left them at that as it's a bit had to file metal back on!