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crash279

2009 WR450 Jetting

4 posts in this topic

I have a 2009 WR450 that I'm trying to get jetted properly, but have a couple of symptoms that are giving me fits. So far the bike has: Fully de-restricted/free mods/ais removed, YZ cams, YZ exhaust system (header and exhaust), R&D power bowl 2. I have a #55 pilot jet and 170 main (bike was jetted when I bought it). The elevation is 650' and my other WR's have always run best with a larger pilot jet.

First off, the bike will not idle properly. Seems to get worse as the bike heats up and it's street legal so it does see its fair share of street use. Basically if I pull up to a stop light, as the revs drop, it will just stall if I don't give it a little throttle. I have played with the idle screw, but it doesn't seem to be consistent. One minute it sounds like it's at half throttle and other times it is just a sort of regular idle.

Next one is if I wheelie the bike it will kind of cut out or run real choppy (if that makes any sense). On the other end of the spectrum, if I go down a hill it will instantly die.

I have tried adjusting the float height, but that hasn't made any difference. Are there any suggestions?

Also, I bought a GYT-R AIS removal kit for my other 2009 WR450 that is bone stock and completely restricted. The kit came with a #50 pilot and a 175 main. That main jet seems really rich. Would I be better off with a JD jetting kit? Any help is greatly appreciated.

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My '06 came from the original owner with the GYTR kit, and I didn't think it was running all that well, so I switched to the JD kit. Runs much better now! Your issue definately sounds like a float height issue! Strange that you tried that and it didn't help. It sounds like you've got a hanging idle too, which generally means your lean on the pilot, or you have an air leak. What kind of idle screw are you using? Some are better engineered than others. Hope some of this points you in the right direction.

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My '06 came from the original owner with the GYTR kit, and I didn't think it was running all that well, so I switched to the JD kit. Runs much better now! Your issue definately sounds like a float height issue! Strange that you tried that and it didn't help. It sounds like you've got a hanging idle too, which generally means your lean on the pilot, or you have an air leak. What kind of idle screw are you using? Some are better engineered than others. Hope some of this points you in the right direction.

The pilot is kinda rich, but I seem to have better luck with the larger pilot jets. The boots are tight and the bike ran fine when I got it (but it was mostly stock other than being de-restricted) so I wouldn't think it is an air leak. I'm running a R&D flex fuel screw. I really appreciate any help I can get. One day I hope to master the FCR carb lol.

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