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ATV carb prob. - interesting issue inside


max power

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Hey kids,

I just disassembled and cleaned the carb on my brothers 2001 Suzuki 300 Kiing Quad. It is a thumper.

His original complaint was that the thing ran fine when cold, but flooded and died when it warmed up.

When I reinstalled the carb (sans airbox) it fired right up but idled real high and the exhaust pipe got very hot and glowed red in short order. It seems to be getting plenty of fuel. It also backfired when shut off.

So my question is, WTF?

Any ideas? :dunno:

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Hmm, but unspent fuel would cool the pipe wouldnt it? I didnt mess with any adjustments.

Not if the pipe is hot enough to burn it. Again, a total guess. Hopefully this will be close enough to the top tomorrow when more guys can see it.

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I've heard that when exhausts glow red like that it's because the timing is off. When the Exhaust valves open up the fuel is still combusting.

The idle should be an easy fix if you can find the Idle adjustment screw...

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I know on the VStars, the pipes will blue due to heat from running too lean. With The air box removed, the carb is able to pull much more air than with the airbox installed, and the mixture is leaning out. Lean mixture will cause your fast idle and your hot pipe. A quick check to see if you're lean is with the filter and housing off of the carb, take some tape and tape off about 3/4 of the carb throat, effectively "choking" the airflow the carb can pull. The reduced airflow should help richen your mixture, and let you see if you've worked out the warm flooding issue before you put the airbox back on.

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I guess thats possible. The settings are all stock though. All I did was take it apart and clean everything and reassemble. No settings were touched.

Didn't his buddies mess with some adjustments though?

Could be lean or really advanced timing. Probably lean. First thing I'd do is knock the idle down. His buddies probably adjusted it. Should have an idle adjustment knob. I can run over there tonight after work and help you figure it out, but I require beer. :D

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I've heard that when exhausts glow red like that it's because the timing is off. When the Exhaust valves open up the fuel is still combusting.

The idle should be an easy fix if you can find the Idle adjustment screw...

I adjusted the idle all the way out and it still idled very high, like half throttle.

I know on the VStars, the pipes will blue due to heat from running too lean. With The air box removed, the carb is able to pull much more air than with the airbox installed, and the mixture is leaning out. Lean mixture will cause your fast idle and your hot pipe. A quick check to see if you're lean is with the filter and housing off of the carb, take some tape and tape off about 3/4 of the carb throat, effectively "choking" the airflow the carb can pull. The reduced airflow should help richen your mixture, and let you see if you've worked out the warm flooding issue before you put the airbox back on.

I did try covering it with my hand, didnt change the idle though.

Didn't his buddies mess with some adjustments though?

Could be lean or really advanced timing. Probably lean. First thing I'd do is knock the idle down. His buddies probably adjusted it. Should have an idle adjustment knob. I can run over there tonight after work and help you figure it out, but I require beer. :D

You know I gots beer. Call me. I might be at Yotas right after work though.

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Is the choke on? Sounds like a fuel enrichment problem to me... did you clean the choke valve? If i remember right there is a rubber diaphragm in there that maybe torn

No choke, did not clean the choke valve (is that the thing that broke on the VTR?) and the diaphragm checks out ok. Might have to try it with the choke disconnected.

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You get this fingered out?

I think so. Cleaned out the carb (it was filthy) and explained to my brother that you have to clean and oil the air filter element once in a while. It was bone dry. He has never heard the word maintenance.

Seems to be running good now.

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