I was looking at getting a cdi for my 400 but am not sure what to get... They have un-limited rev,and a extra 1,000 revs..I have the quad with a pipe,K&N,jetted,air box mod,....Tell me what worked for you!!!

 

I would stick with stock, there is no need for your engine to rev an extra 1,000RPM or more. When you hit the rev limiter you are done making power. The only possible time to consider getting an ignition is when you are running a race cam, otherwise you are just destroying your engine faster.

 

Thanks... What else can I do to make power with out getting into the motor?...

 

nutec or nitrous.

 

lot more strain on engine parts

 

It depends on what you are looking for... If you just want more power for drag racing you would be best off getting inside the top end. A cam upgrade and high compression piston would give you nice gains. It's not as hard as some people think to take apart the top end of a 400EX; it's a VERY basic engine. Get yourself a manual, an extra set of hands and a torque wrench and you would be fine.

If you are looking to improve your speed on trails...you HAVE to upgrade your suspension before you even consider touching the engine.