HELP! 2000 RM125 REVVING HIGH, can you help?

Same!

!!!

The exact same thing happened to me on the weekend. I have a 98 wr200 and after a whole days riding went through some puddles, did a couple of wheelies then all of the sudden thr revs to up to WOT in second, luckily the rear tyre looks like a road one with no knobbies, i was panicking and layed it over and held the kill switch.

BTW when this happened I closed the throttle and that didnt do anything so ...exactly the same thing. Its so scary!

Then I picked it up, gave it a couple of kicks (flooded) and it started, idled a bit funny ( a little high) then it dropped to normal. After is seemed normal to me.

I've had the exact same thing happen on my yz125 as well when i was topping out 3rd and then 4th on a straight on a trail. I really dont know that it is.

PLease help us, we both need help!!!

-Dmitri. :) :)

Airleak at carb/reeds , worn slide in carb, worn needle in carb(notched) , worn carb body, worn/badly routed throttle cable, those are the things i would look at first.

Do a search with the terms "bike runs wide open." A few of us have been through this, and attempted to create a resource thread.
You're pretty lucky to be in one piece. Get this solved before you ride again.

Reminds me of the time I was working on one of my vintage snowmobiles last year. This particular one was a 1973 Skiroule RTX 440 with a Sachs engine.
I was working on the engine to get it going it was siezed as there was some water in the engine and it had frozen siezing the engine so I added some wd 40 and some oil down the spark plug holes and then held a heat gun to the engine until I could get it to turn over. I then set the gaslines from the carb in a widex bottle full of premix (I had removed the tank earlier) I then sprayed a few shots of premix into the carb from another gas filled windex bottle and pulled it over.
The thing went nuts it kept revving and revving and revving I was sure it was going to blow up. It was running so hard it sucked all the gas out of the windex bottle and made the bottle kinda suck in slightly. It kept on revving after the gas was gone (I know now that it was burning the WD 40 and oil that I had dumped down the engine. I did add quite a bit of oil and WD 40 before I realized it wasnt rust seizing the engine it was ice.) Anyways I handed up pulling the sparkplug wires with my bare hands as the kill switch had been disconnected earlier while working on the handlebars and controls (OUCH) it diesled for a few seconds and then finally stopped. It freaked me out at the time in the panicked state I was, I was sure the engine was possessed it ran like crazy even after it burnt all the gas.
If there had of been a belt on that snowmobile at the time it would have been halfway across town and caused some major damage or hurt some people really badly as it would have shot straight out of my open garage.

Crazy story and completley off topic but whatever,

when ever my bike is low on gas it does it

I had this problem and it took me a few tries to fix it. A couple of years ago I had resealed the airbox boot to the box with some sealant. On my second ride after switching to Ultimate 2 (may or may not be relevant) I started having this problem. When I would let off the throttle after running wide open, the bike would surge hard.

Ended up that the sealant was flaking into the airbox and clogging the pilot jet. I found flakes in the airboot and in the pilot.

Since you feel confident that it's not the throttle or cable, I would start by cleaning the carburetor really good. Remove the pilot and see if there is any dirt in there.

Stretched throttle cable? Happenned to me on the weekend.

Yeh, it might stick open. I hit fourth, came to a corner and the bike just screamed. I killed it, tried to start it again and got a backfire. Checked the throttle and it was stuck open. Got it home and pulled the throttle mechanism apart and found the cable was stretched by an inch or so. Thought back about the day's riding and remembered that I had trouble starting it in the morning. It seemed flooded, and now I know why.