Timing ?

[marsrace2]

ok, if I understand correctly advancing the timing on a 90 2 stroke will give it more bottom end but less top end, am I correct?

[BradLoomis]

Yes, advancing the timing will make it fire closer to the top dead center of the compression stroke. By doing this, it makes for a more powerfull explosion by will counter act against the flywheel. By retarding the timing, it will make more rpm but you will lose the torque of the advancement. There are a few CDI's on the market that will electronically advance your spark up to 25 degrees at low rpms, and then retard them back to standard at high rpm's. I had great success with one from Maximum RPM, that I then retarded my stator 10 degrees and gained quite a bit more rpm on the topend.

[marsrace2]

Thanks Brad