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Old 04-30-2005, 02:31 AM   #1
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Default lean sound after coming off full throttle?

hey guys
was doing some high end tuning today and i noticed that after doing a couple of high speeds runs..

the engine seams to have this lean sound after getting off full throttle.. what does this mean ?

i guess this be one or more of many things but i just wanted to know what i can look for ?

also, how do u get rid of small bubbles in te fuel line ?

i tested my tank for leaks, changed the fuel lines and also made the pressure line longer.

thanks heaps!
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Old 04-30-2005, 03:23 AM   #2
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The highrevving after wide open sounds very much like a too lean lowspeed needle, try to richen the lowspeed needle and MAYBE lean the highspeed.
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Old 04-30-2005, 07:24 AM   #3
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It's too lean or you can try to reduce your idle speed.
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Old 04-30-2005, 06:50 PM   #4
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Richen the low end. If you lower your idle, you'll have to richen the low end as well. Start by richening the low end, go from there.
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Old 04-30-2005, 08:40 PM   #5
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This can happen in some circumstances and is not necessarily harmful. Check the temps of the motor and ensure it is running well and i would not worry about it too much. Richening the bottom will help as long as the motor still runs well.
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Old 05-01-2005, 02:28 PM   #6
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Default Sounds like detonation


I too had this same problem a while ago with my Sirio .21 PR-Pro on road engine. Everything would be running perfectly and when I would lift at the end of a long straight, the engine would "run-on" for a few seconds then settle back to normal idle.

After playing with the mixtures, I could never completely correct it.
What I found was the engine was detonating and that was causing the run on condition. I ended up putting .05mm shim and one step colder plug and the problem went away with no change in performance.

Pull the head of the suspect engine and look at the top of the piston and the surface of the head button for minute pits, if they exist then I would say the problem is definitly being caused by detonation. And a shim or two should fix your problem.

Remember to reset the mixtures after you shim the head button.

p.s. I agree, the low end mixture is also a bit lean, which is adding to the engines tendancy to detonate just after closing the throttle.

Hope this helps.

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Old 05-02-2005, 01:41 AM   #7
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thanks heaps for all the help provided

i set the engine back to factory defaults and tuned it that way
engine is awesome now

my prob was with the low end being lean
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