I'm looking to rebuild my CBR. I was only able to find Wiseco piston kit that has 12.4:1 compression ratio standard bore. That's higher than stock. Does this disqualify the bike from supersport class ? ( stock is 12:1)
Does timing need to change if I decide to go with that kit ?
Right now my compression numbers are:
cold and dry : 155 psi
cold with tea spoon oil in the cyl : 190psi
service limit : 178 psi.
Not sure about the comperssion change making you illeagle. Don't have a rule book handy. You may just be able to re-ring the motor. Tear it down and check the pistons for skirt collaps and if they are in specs, just re-ring it and your compression should come back up.
+1mm over is still SS legal.
Other than stock compression ratio pistons is NOT SuperSport legal
check with J&E they do custom pistons but OEM may be best choice
Thanks, Eric.
From the 2009 rule book if anyone wants the exact wording.
6.1 SuperSport
6.1.2
E. Engine modifications include the following:
(1.) Pistons which are no larger than 1mm over stock size may be
used but must be same compression ratio as the OEM piston.