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Jet size

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I have a 04 CRF 250x. I know the stock main jet is 130. What is the pilot and leak jet stock? and is going bigger in size make it richer?

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Bigger pilot jet makes it richer at idle only.

Smaller leak jet makes the AP richer.

Larger main jet makes it richer at WOT.

Do not richen jetting 'because everyone say to'. Only make changes for a good reason, based on solid testing. And then, make one change at a time, test and go from there.

Check your manual to see what size is supplied by the factory. Check your carb to see what is actually in it. I doubt your main is a 130. Probably more like a 175

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I know for a fact 130 is stock... I took it out when I bought the bike new in 04... got a 155 in now. After I put a high compression piton in it and did valve work it now has deceleration pop. Doing some reading I think pilot jet needs to be bigger.

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Decel popping is either a clogged pilot, misadjusted fuel screw or most liely, an exhaust issue, either a leak or worn out packing.

Pilot jet and fuel screw are selected/set for a perfect hot idle only. Very doubtful a change in CR or a valve job is going to affect the idle.

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I did find a partial clogged pilot jet last night cleaned it so we will see what happens. The exhaut is stock and the X model has no packing. I will look for a leak in it.

What is "CR"?

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I suggest using a brand new pilot, it is near impossible to get it 100% clean.

Hold a wet towel over the end of the muffler and then listen for leaks. I bet you'll find one at the head to header junction.

CR=Compression Ratio

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Well I got a new jet ordered and put it in. I went with a 42 pilot. when I was putting the air side boot back on the carb I noticed the boot that the carb and head is, was loose (freaking mechanic):busted: I tightened it and started the bike, fired right up...:busted: with little to no decile pop.

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