Moto-4 Carburetor Tubes - Yamaha Forum : Your Yamaha Motor Products Community & Resource
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post #1 of 3 (permalink) Old 10-01-2010, 07:32 AM Thread Starter
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Moto-4 Carburetor Tubes

I just bought a 1988 Moto-4 350 2-whl drive. I noticed fuel leaking from some sort of carb vent or over-flow tube. After inspecting further, I find 3 tubes coming off the carb, all 3 being open-ended and not connecting to anything:
1) tube off top of carb routed to the front (vent?)
2) tube of bottom of carb routed to the rear (has some sort of check valve in it)
3) tube off top of carb routed to the rear

Are all three of these supposed to just vent to atmosphere or did something come disconnected? I have a Clymer manual, but it most definitely does not describe the routing or function of these three tubes.

I'm new to the forum and also a horrible mechanic. Thanks!
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post #2 of 3 (permalink) Old 08-12-2012, 07:09 AM
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The tube off the bottom of the carb is the overflow tube. Sounds like the fuel is coming from there?

If so then it sounds like you have a stuck float. What that's for is when/if your float gets stuck it doesn't just flow all that fuel into the engine when the bowl is full. If that is what is going on, the best way to take care of it is to take the carb off and pull the bottom off of it (four screws) and then wash the inside down good with carb cleaner. DO NOT GET IT ON THE RUBBER GASKET! If you do it will swell and you can't reuse it.

MODS: Delete this, I didn't notice the original post date until after I replied. I made it to this site from a GOOGLE search and this is what popped up. Sorry.

Last edited by broughy84; 08-12-2012 at 07:09 AM. Reason: Automerged Doublepost
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post #3 of 3 (permalink) Old 04-28-2014, 01:51 AM
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carb, carburetor, moto-4, overflow, tubes

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