Strange starting manners

MXTex

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Feb 29, 2000
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#1
My 98KX250 has always been an easy starter. So when it wouldn't start at all a few rides ago I was surprised. Then a friend of mine pulled it with a 4-wheeler and it started and ran fine for the rest of the day. Ever since then it's run fine but has acted very weird on the 1st start up of the day. When it first lites off, it makes a racket that sounds maybe like heavy detonation. Then it revs to the moon until I turn off the choke. With the choke off it blubbers and wants to die so I oscillate back to choke, it revs, and I go back to no choke. This back and forth action lasts for about 25 seconds or so then it settles down and runs fine. All starting for the rest of the day will be totally normal. Is there a start/choke circuit that could be clogged? Could the pilot be clogged? Most concerning to me is the initial racket the motor makes. The detonation type sound. Could this be lean driven detonation? Within the last year or so, the bottom and top ends have been gone through. That's a long sad story but everything has been fine for 5 months or so now. Bike runs quite well once warm. Any thoughts would be appreciated. My current plant is to disassemble the carb and thoroughly clean. Thanks in advance.
 

darringer

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Dec 2, 2001
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#2
If the weather has gotten colder, a larger pilot jet may be needed. When the pilot circuit is lean, it has a tendency to cause the bike to rev quite high when starting a cold engine.
 
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Nov 18, 2003
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#3
yep, and i def would check it immediately; lean-pilots cause seizures when u back off the throttle at the end of a high-speed straight!