2001 300ex

[aaronwkempf]

I recently got this 01 300ex. It like cuts out and misses when you have it wound up. Any other time it runs perfect. I put a bigger jet in it and I also tried leaning it out by adjusting the needle. I don't know what to try next, could it be something with the valves????????or what?

[tyguy39]

could be worn valve springs
had to change them on my 01 400 ex
was doing same thing
fixed it right up

[bwamos]

Cuts out and misses. Sputtering, etc.. or is it a bouncing rev type of cut out?

If it's a bouncing rev type cutout, you have a dirty connection at the reverse indicator switch below the clutch on the sidecase, or a burnt connection inside the large wireharness connector near the CDI.

[aaronwkempf]

I checked the wiring and it ok, is there any way to check the valve springs to see if they are still good? I am going to buy a bigger cam this winter and it comes with titanium valves and heavier springs so we will see if that helps out. Some one else told me that it is prolly something to do with my carb, would you guys think that may be it?

[John451]

I dont really think it has to do much with the carb since it's a 4 stroke, It sounds valve rellaed, id check the clearance.. then the spring i guess. But you defiantly should check the camchain and make sure its tensioned up right..