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Hi all. I am scratching my head with a problem I have on my 2010 CRF450x. I am hitting what feels like a rev limiter at 6500 rpm. The bike starts to pop and splutter and will not rev past the 6500 rpm. I thought the problem to be the multifunction switch on the handlebars which is a CEV switch with lights, kill switch and horn incorporated. I replaced the switch but no change. Then I discovered that with the lights on my revs would reach 8000 rpm before hitting the same problem. So I removed the switch and wired the bike as it would have been out the shop! Headlight on permanent and still only get 8000 rpm. Remove the bulb 6500 rpm! Really confused. Have done all the resistance tests in the manual for, coil, exciter coil, pulse generator etc and all within spec. I can't do the peak voltage measurement as don't have a peak voltage tested. Any help would be appreciated. Many thanks Simon

Welcome to the site !!

It seems to be a issue with the lighting kit from your description , as the lighting coil and charging coil and ignition coil are all independent of each other , so running without the light should not affect the ignition side , Baja guys do it all the time , unless its backfeeding somewhere in the system , and draining amps from your ignition side of the stator , i would think that something in that kit has possibly already damaged something and this is why your getting normal test results when the bike is sitting , but under a load the system is breaking down , though it is possible that running it with the short could have already damaged either the stator or CDI or even coil , so that one of them is breaking down when the load on the system is changed by removing the bulb , like as if the light was completing the circuit or something , to me the culpret is the kit , the issue is , what damage did it do if its shorting out or backfeeding the system

Thanks for the reply. Why you say makes a lot of sense. When I replaced the switch on the handlebars I checked the wiring and it was wired completely wrong. I know it is wired correctly now. Could that have caused the damage? The lighting kit is the one that comes with the x model I have just changed the rear led to a stop and tail. So how do I find which part is bad or do I have to start changing parts?

You should be able to test the switch and its functions using a Ohm meter/continuity tester , make sure nothing in the switch is backfeeding thru the lighting part of the switch or the ignition part of the switch , each function should have no relation to the other in outgoing power , also make sure nothing is grounding out , also make sure the ground wire is secure , if its loose it could backfeed thru the other wires

Its very possible that it could have damaged one of the components , but you will need to test each item and make sure there is no issue , it would be nice if you had another 450X that you could test your parts on to see if it has the same issue on that one . testing one part at a time

Thanks for the reply. I am pretty sure the switch is now correct but will check it again. However the bike runs exactly the same way with it disconnected so assume the damage has been done to another part somewhere. Would be nice to have a second bike to try parts from.

Hi all. I am still having problems tracking down my fault. Can anyone tell me if I should have continuity between the blue and green wire running to the headlight even with the bike not running and headlight disconnected as I seem to have continuity all the time. Many thanks Simon

Hey mate, did you ever sort this out?? I know this is a real old post, but it sounds so close to my issue!

Mine is doing something that sounds very similar. https://youtu.be/AgJf99oxOmc
Is what mine sounds like, but now that you mention it, I never had a headlight bulb in it when it was working, and it’s not been right since I added one. In fact, it was worse when I flicked it to high beam.

Frustrating hey!!

coming back past this old post of mine, i never came back and said what it was that fixed it!

My bike was doing the exact same thing, and my issue was a dead battery. For ages i was kicking my bike as it had no battery at all. i put an old one in that i had, but it didnt work. I just left it in there anyway. Then i replaced the blown headlight bulb just before a ride weekend. Got there and the bike started breaking down and would not rev past 4000 or so. Was different revs if was on high or low beam, but had me stuffed. Parked the bike for the weekend and drank instead

Long story short, as soon as i got home and put a new battery in all was well again. Hopefully this helps someone somewhere

Thanks for coming back and posting your solution.
I am sure it will help someone in the future.