Problem with stock rev limiter

[wolrahnaes]

OK, so I was out riding, jumping a small (~3.5 feet high) ramp to a flat landing :D, and suddenly the engine began to stumble. I checked my gas and choke, and it wasn't that. I sat for 5 minutes idling and it ran fine. I got back on and as soon as I began to pick up speed it started to stumble again. I stopped, put it in neutral, and revved it. At about 3000-4000 RPM, it stumbled and backfired. This continued with stumbling and occasionally backfiring at those revs. I checked the choke again, but it was off. I rode home, keeping the revs low and I got up to 5th gear, no prob. When I got back, I checked for a clog in the air intake, but that was fine. After two more backfires (that were loud enough to scare the neighbors) I gave up and came in to the pc, and now i'm here...

I think that somehow the choke sensor is shorting out and the rev limiter believes that the choke is on. Where is this sensor located and how would I check it? Also, any other theories on what may be happening?:confused:

[JOEX]

The choke is mechanical not electronic.
Check to see if the main jet fell out, it can happen.

Joe

[wolrahnaes]

a friend of mine told me that he thinks the carb is dirty, but the jet falling out seems more likely since it began after a hard landing. thx.

and the reason i said choke sensor is because it seems that the rev limiter adjusts much lower when choke is on.

also, sometimes when I ride in water, it just suddenly dies and won't restart for a few minutes. It is still warm (i.e. burning to the touch) and seems to be random when it happens, so it's not just getting cold.

[4TraxRider]

Maby a little water on the stator or something like that.:huh And my main jet fell out and did the same thing. It ran horrible and it took me a while to figure out thats what it was.

[JOEX]

How deep of water are you riding in? Alot of spash?
You could be sucking a bit of water into the snorkel.
Another thing to check is the spark plug boot, make sure it is getting good contact.

Joe

If you got mud and water in tailpipe your in for a hell of alot of backfiring. I had my sand tires on and was hyroplanin across the top and rolled it. got it up quick, pushed it out, flipped it up and let h2o drain out and i backfired like hell for a week or so until i cleaned the cylinder and piston

[Sick0]

It sould like your jetting. But I had the same probly with jet falling out. I went to go change the jetting and the jet was just sittng on the cap for the carb.

[Juggalo]

this might sound dumb but it happened to me once, is your spark plug boot on tight?

[wolrahnaes]

The water isn't too deep, up to the top of the front tires at the highest. I check the airbox every time it dies in the water, but I never find any water in there. I will check the spark plug boot.

[toby400ex]

Its prolly what the other people are saying, like the jet might have fallen out, if it isnt that check the electrical connections. My 300ex stumbled when the stator or something got loose. I think the diing thing in the water is from stem getting in the air intake.