I have a 300ex stock. I will be getting an aftermarket pipe, 20" tires on rear instead of the 22" stockers, and K&N air filter. I am lookin at a new front sprocket. The stock is 13. Will it be able to pull a 15 tooth front sprocket or is it too tall. Should I go with the 14 tooth?

 

A 14 t barely fits, you will have to remove the case saver,or modify it to fit the 14, after that,you will need to drop teeth on the rear,or get a cdi with the rev limit removed. If your motor is stock, 20" rear and a 14 tooth will work fine, add an exhaust and intake mods, and you will hit the rev limit.