Engine accelerates without any throttle

Phoenixell

New Member
Feb 1, 2020
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Hello! New engine user/assembler here. I recently bought a Seeutek 80cc 2 stroke engine, assembled it and have been riding the bike for about 40 miles now. Have had this issue come up in the couple recent days that didnt used to be an issue. The bike will lurch forward and suddenly accelerate (not at great speeds but) on its own, and when I try to give it throttle it actually doesnt speed the bike up any extra at all, not even fully open. Meanwhile, when I idle the engine, it almost immediately runs extremely high and loud, unlike any other performance of the engine itself normally. I have been doing research online as to the cause of this problem, and from what I can tell the consensus is that its an air leak.

I would love to know if this sounds correct! If it is, where are all the possible locations to find a leak?
And if its not, what do you think the problem is and why? Im learning as much as possible about my engine.
 
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Morbius18

New Member
Feb 18, 2020
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How would I go about fixing it if that was the issue?
If you haven't already figured it out, You can spray some carb cleaner around the intake & cylinder gaskets to see if the idle changes. It needs to be sealed from carb on. Any extra air entering this system leans out the fuel, causing the idle to raise, which pulls more air and so on.

If your leak is at one of these locations, you can seal it/gasket with a 2 stroke sealant. Permatex motoseal from auto parts store or Dirko HT from a Stihl dealer. I use both and prefer the Dirko HT. The motoseal is runnier, the Dirko HT is silicone based and thicker. Stihl uses Dirko for cylinder bases in some saws and around crank seals. It's heavily used for modded hot chainsaws as well as BMW, Mercedes and other high end supercars.

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Phoenixell

New Member
Feb 1, 2020
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I figured out the problem, just an air leak around the air intake for the carburetor, thanks all for the help! Fixed it with some quick steel