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Dirt Bike revs uncontrollably when started

Old 07-11-2009, 07:33 PM
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ryansiki
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Default Dirt Bike revs uncontrollably when started



Got an on Giovanni 125 dirtbike. Every time it starts it revs uncontrollably.When the chokes on it just iidles. Any ideas to what the problem is AND how to fix it? thanks

Old 07-11-2009, 10:59 PM
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DaveG55
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Default RE: Dirt Bike revs uncontrollably when started

The symptoms you describe sound like a lean condition when the chke is off. If it starts and idles as it should with the choke on then I'd start by making sure the carb needles and jets are clean and set properly (if they can be adjsuted).
Old 07-11-2009, 11:08 PM
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Default RE: Dirt Bike revs uncontrollably when started

Sounds like a good time to do a carb rebuild.....
Old 07-12-2009, 12:12 AM
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Default RE: Dirt Bike revs uncontrollably when started

Yes. Take the carb off and fully apart. CLean and inspect it. Also check the carb boot for cracks on the engine side. Also check (if applicable) the reed cage boot. Anything from the carb to the engine should be sealed tight. It does sound lean to me. Also check to see where the clip is on the slide. If you take the top of the carb off (unscrew it) and pull the slide out there should be a E clip holding the needle in the center on. It will be at the top near the cap. Check to see if it is in the center, top or bottom position.

Kevin
Old 07-12-2009, 12:41 AM
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ryansiki
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Default RE: Dirt Bike revs uncontrollably when started

k I'll try that tomorrow thanks
Old 07-12-2009, 09:29 AM
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Default RE: Dirt Bike revs uncontrollably when started

yea I would open that carb up, take the jets out and spray them out with a air compressor. There is tiny holes in the jets, make sure you can see thru them, if you cant keep hitting them with the air compressor.
Old 07-12-2009, 09:46 AM
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Default RE: Dirt Bike revs uncontrollably when started

sounds like a rich condition to me. Adding fuel or choking the air makes it drop. In any case it is getting more (air AND fuel) than is supposed to. What type of "choke" is it? Is it an actual choke or a fuel enrichment or fuel and air increase?
Old 07-12-2009, 09:02 PM
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Default RE: Dirt Bike revs uncontrollably when started

TO me it sounds like theres either an air leak causing it to go lean,
Or the throttle cable is broken.

If the jets are clogged, the bike would go lean then die or not run at all. Not stay at a higher rpm then idle
Old 07-13-2009, 12:31 PM
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ryansiki
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Default RE: Dirt Bike revs uncontrollably when started

Fixed it. Just did a carb rebuild, runs great too considering it hasn't ran since last summer ,and gas was still left in it.
Old 07-13-2009, 03:30 PM
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DaveG55
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Default RE: Dirt Bike revs uncontrollably when started


ORIGINAL: ryansiki

Fixed it. Just did a carb rebuild, runs great too considering it hasn't ran since last summer ,and gas was still left in it.
That was your problem. If you're going to store a gasolene powered vehicle for any length of time you really should Sta-bil. That will prevent the gas from turning to varnish and blocking critical passageways. I use it in my boat, jet skies, lawn mowers and any vehicles I don't expect to drive for a month or more. Cheap nsurance and worth it when you can go out and the engine fires right up even f it sits for a year or more.

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