300 EX help

[Harv]

Just rebuilt 300ex motor, just 40 over, nothing else special. Starts and runs great, as soon as you crack the throttle it acts like its in the rev limiter. I'd say it gets up in the 4000 rpm range, then rhythmically cuts out. Not like normal rev limit action though, drops several hundred rpm then comes back. Have checked carb, checked to insure that key wasnt sheared on crank. Had motor together once, ran fine but had rough sounding bearin, so i pulled it apart and replaced the countershaft bearings. Put it back together and having this problem. Although, neutral light hasn't workied since I've had it and now it does :rolleyes: !!
Any ideas would be greatly appreciated! Almost forgot, tried cdi box too, no change.

[aDviSol2y]

Make sure your air filter is not glogged. If you have a K&N, take the pre-filter off. I had this same problem, and it ended up being the pre-filter.

[Harv]

Removed filter, no improvement.... Havent actually pulled rocker cover to check cam timing, is it possible to get this kind of problem from being out of time???

[TCracin440ex]

harv ill tell you exactly whats wrong with your quad. on the right hand side of the motor if your sitting on the quad. the side with the clutch cover on it...there is 2 wires you have them backwards. simply take them off. put them on the opposite way and whala your quad is fixed...

whats happening is your quad is hitting the reverse rev limiter. i bet if you put your quad in reverse it will run untill their is no more gear left to run because it has no rev limiter in verse now simply because you have the wires crossed up...fix that problem and it should be golden

[Harv]

Excellent thought! I tried that already! Actually used a different side cover when I put this back together. But you know, wonder if its possible that the switch that runs the limiter could be stuck! Will try that and let you know! First time my neutral light worked since I had it too!

[Harv]

Tried rev rev limiter. When the limiter is on it sounds like it always did. It limits the rpm but it stays at that rpm. When the rev limiter is off, it turns a little higher rpm but doesnt just "max out". It peaks, then drops a couple hundred rpm, in a rhythmical fashion.

[TCracin440ex]

idk then im stumped then man

[Harv]

Still haven't resolved it, open to any suggestions!

[redneck24]

just wondering if you got it figured out my boys has the same prodablem thanks

[mikey726]

Check my reply in the 300ex can't throttle out thread.