94 KDX Engine reving out on its own

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Jenger
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94 KDX Engine reving out on its own

Post by Jenger »

Hey guys,

So I bought a 94 KDX200 a few months back. Really all I mainly had to do was remove the clutch basket & file it down as I had some serious clutch drag. After I slapped the clutch back in, cleaned the carb and threw on a new air filter, she was running great!

I was out riding a really tough trail yesterday & dropped the bike on my way down a really steep rocky hill climb. I managed to stay on my feet, but I had to sprint down the rest of the hill sideways. The bike ran the whole time on its side until I got almost back up to it, then it stalled. When it was running, it wasn't reving out.

So I can start the bike, it will start and sound somewhat normal (maybe idling a bit high) and then over about 15 seconds the bike revs up gradually until its almost pinned. The throttle still works fine & the cable doesn't seem to have any issues. I tried adjusting the idle screw on the carb, but that did nothing.

The only way I was able to get it back home was to ride it with the choke on (it was 95 degrees yesterday). At first it didn't make a difference but then the 2nd time we started it with the choke up, it started up and held a lower rpm so I was able to ride it back up the hill & back home.

So bike revs up on its own, I still have some control on the throttle, the throttle cable seems fine, with the choke up I can get it to run at a lower RPM.

Any help is appreciated! Thx
Thrahl
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Re: 94 KDX Engine reving out on its own

Post by Thrahl »

To me it sounds like lean condition from an air leak somewhere. Check your carb/airbox and see if something came loose. When you run it with the choke on it would bring the fuel/air ratio back around where it should be and not rev up.

I'm assuming that your throttle slide isn't sticking? If you twist the throttle and quickly let go you should hear it slap back down. If it doesn't then it might just be sticking.
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bufftester
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Re: 94 KDX Engine reving out on its own

Post by bufftester »

Had a similar issue a few years back after a particularly bad fall. Turned out that the front brake lever had gotten tweaked and was dragging on the throttle tube just enough to keep the slide from closing once opened. As stated above, look for the obvious air leaks a t the reed block and carb to boot connections, and make sure your slide is moving freely.
KarlP
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Re: 94 KDX Engine reving out on its own

Post by KarlP »

It sound like you goobered up the throttle cable or grip and it is not closing all the way.
You may also have got the float stuck mostly shut in the carburator. Not too likely, but possible. I'd look to the cable first. It has to sit in that bent tube in the top of the carb properly and that is hard to see unless you pull the rubber boot up.
'08 KTM200xc
'99 CR/KDX Hybrid with that RB stuff done to it
KX100 for the boy
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