02 Big Bear 400 4x4 carb leaking gas top tube - Yamaha ATV Forum
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post #1 of 3 Old 08-18-2009, 10:54 AM Thread Starter
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02 Big Bear 400 4x4 carb leaking gas top tube

leaking gas out of the top tube by the air mixture screw after I removed my carb on an '02 400 Big Bear 4X4 as it was leaking gas out of the bottom drain/overflow tube; so figured it was a stuck float and did not know what else to do (already sprayed and ran gumout through carb). The float seemed stuck when I took the bowl off.. I moved the float up and down and it seemed ok.. so when I put the carb back on the quad it now runs like it is cold with the choke on (alomost sputters) and leaks gas out of the top tube (not sure what the name of the tube is but essentially it just goes out to the atmosphere). If I turn the gas petcock off it runs great for about 15 seconds until it runs out of the gas in the carb.

Any help would be greatly appreciated... thanks.
gbarry is offline  
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post #2 of 3 Old 08-31-2011, 04:20 PM
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I have the same problem

I have this same problem with a 2001 Big Bear 400. How did you fix this ?
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post #3 of 3 Old 09-08-2011, 10:35 PM
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It sounds like the float needle is not completely sealing up and allowing gas to overflow the normal level in the bowl. When you turn off the petcock the fuel in the bowl is being used up so the level is more like normal, so it runs better.

This is not terribly uncommon especially on older carbs. Try (carefully) removing the float to get a good look at the needle (valve). You can remove the needle and wipe it down real good, carb cleaner, etc. Just be careful if you pull the float needle tube out as they have small o-rings that can get torn and then it will constantly leak.

Beware of the cheaper aftermarket rebuild kits as the new float valves that come in them are sometimes worse then the one you are replacing.

In theory if you get the float, float needle, and complete valve system working it can not over fill the bowl with fuel.

Mike a.k.a."Secret Weapon"

(919) 803-0883
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