Whats size jets?

[blasterkiller14]

I run with no airbox lid and a custom 450r full exhaust:o ...dont ask...and I run stock jetting, the engine rus pretty cool and it is fine on mid, high throttle...whould I buy different jets, and if so what size?

[bwamos]

Do plug checks.
You just need to get it running good and want the plug to be a dark golden brown.

You must be loosing a LOT of low end torque with a 450r pipe on a 250. ;)