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03 yz 250f carb

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So I couldn't find anything about this, but I have a bad throttle/idle screw and I was not sure if it could cause this problem. I have a terrible bog from idle to about quarter, nothing resolves this I have pilot jets sizes 35-50 and neither cleared this up, I also changed the clip adjustment a couple times as well. The carb has the FMF jet kit without the FMF needle, also has the quickshot 3 ap cover (which made things a little better)... The bike runs great climbing hills at high rpms but when you lose momentum there's no low end it just bogs and stalls. Any feedback on this would be appreciated thanks.

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Have you ever changed the stock leak jet? It's located in the bottom of the bowl. Stock size is 100 which myself and I believe a lot of others find too large. I can't remember what size I wound up with - I'm thinking something like a 50. Just in case you're unfamiliar with the leak jet it determines how much of the pump shot bypasses or "leaks" back into the bowl instead of going out of the nozzle. In this case a smaller jet means more fuel delivered. You can also search for oring modification. I never needed to do this on mine but still might help you. Clay

Edited by nuity5

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Well here's the thing, the quickshot3 let's me dial in my leak jet anywhere from 50-70, (70 being the highest in the instructions for the qs3) but I can always guess on going higher. I've never heard of the oring mod but I'll look into it to see what it consists of, thanks.

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I wasn't aware the QS3 was an adjustable leak jet. I'd set it for a 50 and give it a shot. The oring modification basically adds more tension to the accelerator pump spring for a quicker delivery. Beauty of it is it costs next to nothing and is quick and easy to try. Also try looking through the jetting database. There might be something in there that will help also. Clay

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OK so I did the mod and it almost made things worse my bike ran like crap, then I got it closer with the qs3 then I noticed blue smoke and a lot of it, and it's a brand new top end with only 14 hours on it ) : disappointed in that, thanks for the help but it looks like I have a lot more other work to do.

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