backfire problems

Joined
Sep 27, 2007
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#1
i have a 01 yamaha wr250f the bike starts but back fires really bad i have changed the jets in my carb but nothing is working.
 
Joined
Oct 19, 2006
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#2
Are you trying to run it with the hotstart knob out? The jets may be clean, but the carb needs to be properly adjusted. Is the seal between the pipe and head leaking?

As long as that bike has been around, it's probably due for some valve work.
 
Joined
Sep 27, 2007
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#3
i'm not running it with the hot start out. i did a adjusted valves afterwards it sat for the summer. i cleaned the carb and Now i'm having trouble
 
Joined
Jan 27, 2000
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#5
When you cleaned your carb, did you remove ALL of the jets and make sure the orifices in the carb were all clear? Also, did you remove the accelerator pump cover on the bottom of the float bowl and clean it out? Sediment can collect in there and cause the bike to not take the throttle correctly.

Check the rubber pad on the end of the hot start valve for damage. Make sure the pad is in good condition and has a ring imprinted on it where it seals against the orifice. Be sure the rubber boot on the hot start valve is seated correctly. If this boot is dislodged, it will hold the hot start valve open a little.

Do a compression test. Your valves may be adjusted correctly but you may have one that is not sealing properly.
 
Joined
Sep 27, 2007
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#6
i found the problem i took the carb apart again and found that the plate on the slide was in wrong :cool: