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Neighbors bike

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My  teenage neighbor has a 250x and rides with us. His bike is to lean. It's a B to crank, which is indication of lean. It has an fmf power bomb header and fmf powercore 4 exhaust. If you ask me what jetting is the average jetting for my favorite bikes, I can tell you what will work. So i asking you guys what should work here. Does not have to be perfect, I don't plan to weld on a bung and hook up an oxygen sensor. I just want to get it to not be such a hassle for him. He's frustrated to the point of not riding with us tomorrow. I can dial in the pilot jet with the highest idle from the air screw  pointing to the correct jet, but the main, if I pull the bowl to change a pilot jet, I will go ahead and change to the recommended main. His pipe gets glowing at night time. Waaaaay to lean. On one hand, I like to help the neighbors, on the other hand, I don't want to be depended upon, or blamed if something goes wrong in the future. But I hate to see him stay home from riding

Edited by 1gr8bldr

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I have an '07 CRF250X with FMF Q4 and I'm running the red needle and 165 jet and it starts perfect,no flat spots, strong through the entire rpm range etc. When I got it the bike the blue needle and 155 jet was in it and it was a bastard to start also. I thought the valves were out of spec since that combo is what's recommended by JD. I checked the valves over and over and always in spec so I switched needle and jet and so glad I did. It's like a totally different bike now.

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No matter which needle or main jet (or exhaust for that matter),

 it should have no effect on starting the bike as they only begin metering fuel at larger throttle openings. (they don't flow at idle)

 

First issues that affect starting / idling is a dirty/plugged up carburetor (slow jet circuit)

and out-of-spec valves (worn valve faces, clearance too tight etc.)

Edited by mlatour
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mlatour is correct, all things being good, needle and main jet do not come into play for starting.    You didn't mention how old the bike is, but sounds like the carb needs an overhaul and the valves checked.

As far as the jetting,  many list their setups here:

which is in the FAQ sticky at the top of the forum.  Most go with a JD Jetting kit, but you can do it on your own.  However the kit does come with a custom multi-taper needle along with a handful of jets and instructions on what to use when.

Jim.

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If a 250X won't start with a 45 pilot and the fuel screw at 1.75 turns out, something else is wrong.

You don't have to pull the bowl to change either jet. Loosen the clamps, slide the bottom of the carb out to the left, remove the 17 mm bottom plug, and here's the tip-lay the bike down on it's right side so that you can see and easily get the new pilot started without gravity fighting against you. Five minute job. I like to stick an air compressor blower nozzle into the pilot hole while the jet is out to discourage chunks of solidified gas crud from sticking around.

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I think I have an extra swingarm I would be willing to part with.  If you are interested, send me a PM.

Picked one up off eBay, but that you very much for the offer

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17 hours ago, Undercover Poe said:


Picked one up off eBay, but that you very much for the offer

gotta love ebay for things like this.   Less than $50 ?

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12 hours ago, Undercover Poe said:

Unfortunately more than double that. $105 w/ shipping but whatever. That's what makes the world go round

Ouch

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