California sea-level jetting... suggestions?

California XR650R

I bought my XR650R up in the mountains near lake Tahoe... about 4000 feet. Now that the bike's down here in the flatlands near San Francisco, I'm getting some popping, sputtering, and hesitation on deceleration (closed throttle), particularly when gear braking.

I don't know much about jetting, but from what I have read, I would guess that my bike could use a slightly larger main jet, a mixture screw adjustment to richen things up, and possibly a larger pilot jet. Please let me know if I'm on the right track!

Unfortunately, the guy I bought it from couldn't remember which sizes he had the bike jetted to... damn.


Yeah Ironbeak you're on the right track, probably lean after that much elevation change (as evidenced by the popping). Here's a few articles on jetting: There are 2 or 3 articles on jetting. Usually I am able to change my main jet up/down one and adjust my mixture screw for 2500-3000' change in elevation (XR600). For 4000'of elevation change I'm guessing go up two on the main and one on the slow and readjust your mixture ??? Trial and error and read the plug after each change. Good Luck.

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