Buddy 125 carb problem - probably lean

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chuckcal
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Buddy 125 carb problem - probably lean

Post by chuckcal »

2007 Buddy 125 was stored for 4+ years, performed all the normal revival maintenance. Starts fine, idles fine. Bogs on partial or full throttle after warmed up. If I cover the intake with a finger it throttles up great, both partial and full throttle. Plug color is too light (but not white). Seems to point to lean condition.

I've had the carb apart several times, jets are clean, the rubber diaphragm is intact and installed correctly. The slide moves when compressed air is applied.

I tested for leaks, intake, petcock vacuum... no leaks found.

Air/fuel screw is set to basic 1.5 turns out.

Stock intake, clean filter, new fuel lines, filter and fresh gas.

What did I miss?
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wheelbender6
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Post by wheelbender6 »

Sounds like you tried everything I would have tried. Sometimes you just take it apart and reassemble it and it will clear it up.
-Hopefully somebody will have a better, easier idea.
2013 Buddy 125, Prima Pipe, #95 main jet, Orange CDI
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Stanza
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Post by Stanza »

Buddy 125 classic diaphragm problem. Take the upper diaphragm off the carb, and put a smear of grease around the upper and lower edge of the diaphragm where it seats in the carb. What's happening is that your seal is leaking a little right now, and the diaphragm isn't getting enough vacuum to pull up the throttle slide all the way.
chuckcal
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Post by chuckcal »

I will try that, but does the fact restricting the intake with a finger does help it throttle up fit with the diaphragm diagnosis?
Stanza wrote:Buddy 125 classic diaphragm problem. Take the upper diaphragm off the carb, and put a smear of grease around the upper and lower edge of the diaphragm where it seats in the carb. What's happening is that your seal is leaking a little right now, and the diaphragm isn't getting enough vacuum to pull up the throttle slide all the way.
chuckcal
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Post by chuckcal »

I tried lubing the diaphragm edges, didn't improve the issue, couldn't get above 30mph, with bogging entire way.

Then restricted the intake about 1/3rd and was able to smoothly hit 45mph, not fully open, no bogging at partial or full throttle. I have no basis to know if acceleration is normal or not. Probably will leave it like this for the first tank with some seafoam in it, then de-restrict the intake, see if its better then.
chuckcal wrote:I will try that, but does the fact restricting the intake with a finger does help it throttle up fit with the diaphragm diagnosis?
Stanza wrote:Buddy 125 classic diaphragm problem. Take the upper diaphragm off the carb, and put a smear of grease around the upper and lower edge of the diaphragm where it seats in the carb. What's happening is that your seal is leaking a little right now, and the diaphragm isn't getting enough vacuum to pull up the throttle slide all the way.
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DeeDee
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Post by DeeDee »

Check for a vacuum leak, or a cracked intake boot. Sounds like it is somehow getting way more air than needed.
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JettaKnight
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Post by JettaKnight »

DeeDee wrote:Check for a vacuum leak, or a cracked intake boot. Sounds like it is somehow getting way more air than needed.
This.

For that age, some of the rubber will start to crack.
chuckcal
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Post by chuckcal »

DeeDee wrote:Check for a vacuum leak, or a cracked intake boot. Sounds like it is somehow getting way more air than needed.
Just to close this topic, the problem was the gasket around the air filter cover. Parts of the gasket were in really bad shape. I had tested for leaks near the carb, not out there. Removed the cover, put some sealant around the edges, screwed it down tightly and the scooter runs properly now.
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