Motorcycle Repair: Problems starting a Yamaha FZR250, yamaha fzr250, valve seals

Question
Sorry, that was 10 PSI not 10 kPa.

-John

Answer
Hi John.
 This is looking like your valves are either WAY off or you have a hole in the piston, or more likely, the rings and/or valve seals are shot.  I suspect that they were on their last legs when you last got it started up.  But when it gets fixed, the power will be scary compared to what it was.

You'll either need the repair manual (which is handy for a lot of other things to do on the bike) to check tolerances or take it to a shop to properly check and repair.

Good luck.
FALCON