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YS 120NC bubbles in fuel line

Old 06-22-2005, 06:04 PM
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Todd D
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Default YS 120NC bubbles in fuel line

Dave,

I have acquired a YS 120NC used. It starts and runs good and will idle at 1800. Problem is at about 1/4 to 1/2 throttle it stumbles or surges a bit and I notice bubbles in the fuel line going from the regulator to the carb. The bubble disappear abve half throttle. They are there between idle and 1/2. Is this from the diaphragm? Should I start here by changing it? Is there something else I should be concerned with? Also notice a lot of fuel spitting out the carb during runs. Anything I can do about this?
Thanks,
Old 06-22-2005, 07:22 PM
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Dave Shadel
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Default RE: YS 120NC bubbles in fuel line

It may possibly need a re-build of the regulator, replacing plunger, spring and diaphragm. Make sure that the air bleed hole in the carb barrel is drilled to 1/8". If not, do it yourself, as it is not difficult. The hole is located in one of the blades of barrel, and as stock it is about 1/16". This will help the problem you have if it has not been done yet.

Do this before doing the other fixes., and nothing further may be required.

Good Luck!
Old 06-22-2005, 08:57 PM
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Todd D
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Default RE: YS 120NC bubbles in fuel line

Thanks Dave! I removed the throttle plate and found that the hole was only 1/16, so I opened it up to 1/8 and will try it. Will this help the fuel coming from the carb also? The regulator screw should be flush with the body (approx) correct? Also I noticed that the regulator screw is really easy to turn, like I can do it with my fingertip. Is this okay?
Thanks again
Todd
Old 06-23-2005, 09:34 AM
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Dave Shadel
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Default RE: YS 120NC bubbles in fuel line

The reg screw should not turn super easy. It needs a new o-ring.

Go to www.ysperformance.com and follow the running instructions, but just disregard the part about the idle screw since you don't have one. The fuel blubbering out the carb is because the reg is too rich. you might need to turn it in 1/4 or 1/2 turn but don't do it until you have tried the barrel mod.

Let me know.

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