I've got a 2001 Polini X-1 Works that has lost some low end power an compression. We got the bike in February and it ran like a scalded dog. Now, it seems to run fine but it doesn't jump off the line like it used to. I ran a compression test and only got about 90 psi so I put in a new piston (C) and ring in the (B) cylinder. I gapped the ring end to approximately .008 which is within the .004-.012 range shown in the manual. I put everything back together and the compression is still the same. I also replaced the reeds and it made no difference.
What else could it be? Do I need a tighter ring end gap? I thought about crank seals but the bike seems to idle fine.
What else could it be? Do I need a tighter ring end gap? I thought about crank seals but the bike seems to idle fine.