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Jetting Help

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I have been experiencing a little pop on decel and also the bike will not return to idle for a second or two after letting off the throttle. There is a stock 40 pilot jet in it and a 165 main??? This seems super rich compared to the 155 main it calls for. I am the second owner so I do not know why it has a 165 main in it. Bike is all stock. Alt is approx 500ft above sea level. I have also turned the pilot screw out approx 2.5 turns from when the bike starts to die. Please help. Thank you! :thumbsup:

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i might not get this right but ill try: popping is a lean condition try another 1/4

to 1/2 turn out see what happens also in the jetting sticky,i think its the first thread sticky tells you that anything less the 3/4 in to more than 2-3/4 out you should change your jets acordingly to3/4 is to lean over 2-3/4 is too

rich try in two size increments.dont base on me you guys if i got this wrong.

oh yea you need to lightly seat in your screw and back out from there so you know exactly where your at.

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You should probably take the pilot jet out and see if it's partially blocked/clogged.

Make sure you don't have any air leaks. Tighten the carb boots.

Like white stallion said... popping on decel is caused by a lean condition in your pilot circuit. If it's not dirty you might be able to turn the fuel screw out to clear it up or go to a 42 pilot jet.

Also, unscrew and clean out the hot start on the carb. They get gunked up and start hanging open causing it to run lean.

Going richer on the pilot should clear up your hanging idle.

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Do you have the service manual or owners manual to it? I have an 06 and the owners manual came with a chart that tells you what jets to put on depending on the heat, track type, and alttitude. If you dont have either, try searching jetting chart for Honda CRF 250.

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It may be the hot start. It doesn't sound or feel like it is sticking, But I will try to clean it out once I get the bike clean from riding today. Thanks :thumbsup:

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Check the bolt between the exhaust and the header cuz you might have an exhaust leak. I thought my 05 was to lean but i found that the bolt felt tight but the more i tightened(was really tight) The pop slowly went away. Oh and you said that you thought that a 165 was really rich for 500 feet saying that it called for a 155?? I looked in my manual and you should have bout a 170-172 for stock(manuals specs are typically rich) I run a 168 with needle at 2nd at 3000 feet and i feel it runs right, maybe a tad lean i think.

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