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Old 02-12-2010, 08:57 PM   #1
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Default engine wont stop peek revving

Hey guys.

My LRP .21 was going sweet. then it started to keep on revving while jumping, or when running flat out and backing off the throttle.

Now it seams to be worse. If i have it on my starter box, and rev it up, it will peak rev until i hit the brakes. the carby is returning to its idle position, so its not getting stuck open. I have taken off the carby, and pull start and cleaned them up and tighten them all up, so i dont think its an air leak.

I have reset the needles to factory, and even changed to a different carb that was running sweet on another motor, but still the same problem.

Anyone got any ideas?

thanks
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Old 02-12-2010, 09:13 PM   #2
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Hey guys.

My LRP .21 was going sweet. then it started to keep on revving while jumping, or when running flat out and backing off the throttle.

Now it seams to be worse. If i have it on my starter box, and rev it up, it will peak rev until i hit the brakes. the carby is returning to its idle position, so its not getting stuck open. I have taken off the carby, and pull start and cleaned them up and tighten them all up, so i dont think its an air leak.

I have reset the needles to factory, and even changed to a different carb that was running sweet on another motor, but still the same problem.

Anyone got any ideas?

thanks
You're either to lean on the top (and to fat on the bottom masking the problem) or you have an air leak.
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Old 02-12-2010, 09:17 PM   #3
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i thought if it kept reving and would not return to idle it was to lean on bottom, o well,

anyways, read the tuning bible it should explain what you need to do and do it very quickly, you can blow your motor if you keep running it the way it is.
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Old 02-12-2010, 09:19 PM   #4
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Check your throttle linkage to see if your carb returning to idle position. Richen your bottom end, sounds like it is too lean. If after richen the bottom end doesn't help, seal your engine and replace the front bearing.
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Old 02-12-2010, 09:20 PM   #5
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and if you are not already, run a ruberband around the carb and on the throttle post, that way it will pull the carb closed and not rely on the linkage to do all the work.
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Old 02-12-2010, 09:21 PM   #6
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Originally Posted by aaron joy View Post
Check your throttle linkage to see if your carb returning to idle position. Richen your bottom end, sounds like it is too lean. If after richen the bottom end doesn't help, seal your engine and replace the front bearing.
+1 and since you have gone back to factory settings already, I would lean towards an air leak. They can be very sneaky.
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Old 02-12-2010, 09:29 PM   #7
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Sounds like a clutch isssue. Shims might be off. Or the shoes have melted and the ends are sticking to the clutch bell. Try grinding the shoe. Let us know what happens.
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Old 02-12-2010, 09:30 PM   #8
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Sounds like a clutch isssue. Shims might be off. Or the shoes have melted and the ends are sticking to the clutch bell. Try grinding the shoe. Let us know what happens.
If it were a clutch issue the motor would die when the brakes were applied, right?
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Old 02-12-2010, 09:37 PM   #9
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check to see that your head is tight and check buttplate for leak

not exactly the pinnacle of high quality , air leaks are abundant on these engines , use lucky 7 and seal the poop out of it

or what maximo said
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Old 02-12-2010, 09:37 PM   #10
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thats a Picco...i bet it has a leaky carb seam !
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Old 02-12-2010, 09:40 PM   #11
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I had the clutch off, the shoes didnt seem worn. The clutch bell had 2 groves worn into it from teh shoes, and a ridge left from where the shoes have a gap for the shoe springs. is this normal?
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Old 02-12-2010, 09:45 PM   #12
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Doesn't sound like a clutch issue in the first place. Take Houston and Maximo's advice and check that first. These guys are engine masters.
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Old 02-12-2010, 10:00 PM   #13
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I had a similar problem. Check the rubber boot on the carb. When my carb was closed everything was normal as soon as I reved the engine it would wind out; I found a small cut in the rubber boot. but would only surface when the carb was open exposing the cut.

I believe you have air leak.
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Old 02-12-2010, 10:17 PM   #14
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I had the same problem on my B5. Even changed carbs with a buddy who had the same engine. Same thing would happen even with my buddies carb on. Back plate looked fine. Changed fuel line. Could never figure out the problem. So I hope you can find the problem and share.
Thanks
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Old 02-12-2010, 10:47 PM   #15
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Originally Posted by JANKEII View Post
I had the same problem on my B5. Even changed carbs with a buddy who had the same engine. Same thing would happen even with my buddies carb on. Back plate looked fine. Changed fuel line. Could never figure out the problem. So I hope you can find the problem and share.
Thanks
your answer below probably

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thats a Picco...i bet it has a leaky carb seam !
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