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Pop pop pop, help

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2005 CRF250R valves in spec, starts and idols great. It will warm up and rev normal. As soon as you put any power on the engine it will backfire like crazy. I suspected a dirty carb, with a clogged curcuit. I cleaned it and it went away. After a few hours of use (less than 10) it did it again. I cleaned the carb and wasn't as lucky. It just won't clear up. All the normal stuff checked. A mechanic at the track said it may be electrical. Could it be a bad connection that I may of bumped on one of these cleanings and now it refuses to go? HELP

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I've been told by a race mechanic if it backfires when you let off the gas it's jetted too lean.

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Take a look at the diaphram on the carb, and then head towards the coil. More likely the coil if it acts up after it gets hot. Eventually they just won't run hot when the coil is faulty. Make sure your pilot jet has a perfect concentric circle when viewed through a magnify glass.

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Clean out where the hotstart goes into the carb, my buddies kx had the same problem. Inside gets corroded up after a while which makes the hotstart stay on constantly, clean it out and it should run like a top!

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Talked to a mechanic today and explained symptoms. I had indicated that when the bike warms up it gets worse. He thought that maybe the stator was having issues and that the temp change would cause it to fail or cause an intermitting problem resulting inthe backfiring. I am going to swap stators from another of our 250's and see what happens.

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Found a tear in the outer cover of the kill switch wire. Appears that when the bike revs it would build enough energy to arc out on the frame or fork bridge. I will replace the wire but for now repaired it. Runs like new!

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There's something new! Never seen that happen before but I guess will cause it to short out and pop. Nice!

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Found a tear in the outer cover of the kill switch wire. Appears that when the bike revs it would build enough energy to arc out on the frame or fork bridge. I will replace the wire but for now repaired it. Runs like new!

Great to hear you got it figured out.:lol:

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