Southern California Carb settings for 05 CRF450

Just got my 05 and am racing it this weekend at Glen Helen Saturday and sunday.

Only ridden it for about 40 minutes so far. I'm coming off a series of 250 four strokes so I'm familiar with how they should run.

This is the problem I'm having The bike doesn't want to idle and when letting off the throttle it backfires like hell.

Anyone in So Cal that can tell me how to set the carb I'd appreciate it?

What jetting are you running?

Idle screw settings?

Fuel screw settings?

Thanks

Steve Landsberg

OTHG & Vet X # 211

I thought you were faster on the little bikes. Guess you are going to give the big one a try again. Mike(I bought your 04 yz250f).

Well, I can't be for sure on jetting in SoCal, but I know mine did the same thing here in Illinois, when I first got my '05. I am at 875 ft. above sea level and the temp is 50-70F, currently. Mine wouldn't idle and popped and backfired like mad. I just backed out the pilot screw a little at a time until it stopped. Runs great now! Good luck! :cry:

I also live in So Cal and my bike ran lousy when new. I started by turning out my fuel screw about a full turn but that didn't help much. I talked to the parts guys at Cal Coast where I bought my bike and they said the 05's were lean. I went to the 145 pilot and a 172 main. The 145 pilot took care of the backfiring when I chopped the throttle but surged a bit at mid-throttle. I am about 1.5 turns out on the fuel screw. I went to the 170 main and this seemed to help but now the bike cuts out occasionally during full throttle out of turns in the rough stuff. I did remove the backfire screen and added the twin air filter.I am still searching for the right jetting but the 145 pilot helped with the backfiring. I am kinda bummed because I never touched my 03 jetting and rode from sea level to 8000 ft without a problem.

I also live in So Cal and my bike ran lousy when new. I started by turning out my fuel screw about a full turn but that didn't help much. I talked to the parts guys at Cal Coast where I bought my bike and they said the 05's were lean. I went to the 145 pilot and a 172 main. The 145 pilot took care of the backfiring when I chopped the throttle but surged a bit at mid-throttle. I am about 1.5 turns out on the fuel screw. I went to the 170 main and this seemed to help but now the bike cuts out occasionally during full throttle out of turns in the rough stuff. I did remove the backfire screen and added the twin air filter.I am still searching for the right jetting but the 145 pilot helped with the backfiring. I am kinda bummed because I never touched my 03 jetting and rode from sea level to 8000 ft without a problem.

Try putting the #168 main back in. I think the switch to the bigger pilot was a good move, but I think you may be rich when wide open. Just try the #168 main, keep the 45 pilot, and warm it up good, adjust the fuel screw to obtain the highest idle RPM, and reset idle to desired setting.

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