im assuming that they raise the rev limiter. but doesnt the manufacturer have it set where it is a safe rpm? i have a 300 ex, what rpm is my limiter set at? thanks, nathan.

 

Not sure what your rev limit is, but it should be in your manual... I borrowed an aftermarket rev box from a friend one day at the dunes, and yes, it does raise your rev limit, but it also changes your ignition a bit. I had a Big Gun CDI plugged into my 400ex, and it was amazing how much harder it pulled in 3rd gear. I wasn't over revving it, it just seemed to add a little "pep" to my motor. I won't run one of these all the time, because in the dunes you do rev your motor alot, and I want the safety of the stock rev limit. These boxes do work, but there is a risk involved with using them.

 

not much if you're still running the stock cam.

 

If you have pipes on that 300ex you will notice a gain in power and the pipes do utilize some extra rpm's that the stock rev limiter never let you reach. the 300ex has a very low set rev limiter, helk i'm running a 14 thooth front sprocket and still didn't bother using first gear that much when i still had my stock rev limiter. Since i installed a aftermarket CDI i've noticed a much stronger pull in 1st through 3rd gear and a higher top speed since it no longer cuts out in fifth when i hit the limiter. As for saftey, as long as you can tell when i motor is over reving, (on the 300 it kinda feels like a drop in pull) then you will have no problems. But if you choose to run without a limiter make sure you don't miss you're shifts too often, rebuilding four strokes is expensive.