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Austin Phillips

YFM250 carb problems not running right

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I have a yamaha beartracker 250 (yfm250) its not running right. starts fine mostly ...idles but if i give it gas it boggs out and dies before it even can carry its self ... I cleaned the carb ... put everything back and same issue. so i bought a new carb and intake boot.... replaced both things and still the issue persists.  So i have a new carb .... does the Air fuel mixture need to be set on the new carb? If so how do i do that? i ave looked everywhere for details on my bike and carb but cannot find anywhere that reads that the skrew needs to be adjusted out to  7 full turns or somthing to that effect..

 

The bike ran fine until bad gas was put into it... i did remove and empty the gas tank. removed petcock cleaned and rebuilt that.....

i also noticed that the new carb ....the bottom skrew for draining the bowl was closed all the way when i got it.. carb wouldnt get gas until i loosened it... now the bowl will drain ... i thought that that float stops this from happeneing....am i wrong?

 

 

 

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Welcome to Quadcrazy Austin. The new carb that you purchased was it an oem carb or aftermarket? There should be no reason to have to replace a carburetor unless it’s cracked, stripped screw holes , or damaged beyond repair. But most of the time its prob just in need of a good rebuild kit including the jets. 

The aftermarket carbs are not really so good  unless it’s a really good production aftermarket company that specializes in carburetors and that would cost you just as much as an oem carb. 

Especially since it was just a bad gas issue.  

There are multiple tiny ports/holes in the carb AND the jets that need to be unscrewed and cleaned as well.  There are small holes in the jets, on the sides, down the middle etc. 

As far as the air/fuel screw I would turn it all the way In until snug, not super tight and then come back out two and a half turns out. 

Once the bike is running you can adjust in or out a bit on the screw to dial it in.   I would also change the spark plug.  It could be fouled up as well. 

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One other thing I didn’t address was the screw at the bottom of the carburetor. That screw should remain tight.  It’s meant to drain the bowl.  There is a black hose attached to the bottom of the carb that is an over flow.  That would allow fuel to flow out of that hose if the float fails and keeps filling the bowl up it would drain there instead of filling the engine with gas.  

There should be a hose connected to the upper side of the carb as well. That’s a vent line. Make sure that hose is clear. Pull it off the carb and send a little air through it.   

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