Dirtbike wont idle right...PLEASE HELP!!?

Question

I have a suzuki 125 dirtbike, it will start up on the first kick...the problem is that once it starts, it just keeps revving higher and higher until I have to kill the engine. It acts like the choke is stuck on, but I checked the choke lever, and it works fine, doesnt stick at all. I tried to play around with the idle on the carb, it will idle for about 5 secs, then starts revving again all by itself, like the choke turned back on again. I was wondering...the choke cuts off air and feeds just gas to start right? so if the air intake was maybe blocked, or the filter was super dirty would this make it run like the choke is on?? IDK...I been going crazy all day...please if you have any ideas at all, it would be greatly appreaciated. Thanks guys...

Answer 1

well like you said, sometime it could be the air filter. what is check and clean the air filter then follow it back to the carb. and some times on 2-strokes when it isnt getting air, it tries to run off of the vapors and it makes the bike rab up

Answer 2

clean your jets (small brass tubes inside the carb, use a tooth pick or compressed air) clean the filter too.. even fi this doesn't fix the problem, chances are pretty good it needs it anyways... (unless you have a pre-oiled filter make sure you oil it... they make filter oil, but i just use 90w gear oil...you don't want it sopping wet or anything, but you don't want it 100% dry... just coat it in oil and squeeze it as hard as you possibly can...)

it would help to know whether we're talking about two stroke or four stroke...

"What happens if you totally disconnect the throttle cable at the carb end? It can't rev infinitely. Your leaving something out. It starts OK, then revs and revs and rev, you adjust the s***w, the idle comes down, and it starts all over again? Well, the idle s***w would have fallen out by now. I say it's the throttle or the actually throttle plate itself is loose."

that's what i was thinking... except i went over my bike and found nothing on my accelerator cable that could be 'loose' and causing this... it's just a direct line from the grip to the carb, no adjustments to be made anywhere along the line.

my clutch can be adjusted at both ends... but my accelerator can't be adjusted anywhere... (is this even normal? lol)

well there is one adjustment but ti's pretty obvious... it's directly on the throttle handle and it's a little s***w you can turn... but on mine it can only be tightened enough for a idle that's just SLIGHTLY over normal... it can be loosened til a point where you can turn the handle half ways and it will just take up the slack, but it can't be tightened enough to really cause abnormal idling..

Answer 3

What happens if you totally disconnect the throttle cable at the carb end? It can't rev infinitely. You're leaving something out. It starts OK, then revs and revs and rev, you adjust the s***w, the idle comes down, and it starts all over again? Well, the idle s***w would have fallen out by now. I say it's the throttle or the actually throttle plate itself is loose.

Answer 4

It sounds like its running lean.  Lack of gas available to the engine or to much air getting in. carburetor mounts, crank case crack, seals on crank case leak, jet has a chunk of yuck that restricts the gas, just for kicks check the spark arrestor, worst case the piston and barrel may be scored  

Answer 5

try starting your bike and winding the idle s***w all the way out then when the bike warms up wind it in untill you get it to idle properly. Most bikes will idle higher when they are cold.