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dstark

Jetting 650L

8 posts in this topic

As the bike comes lean from the factory it could use at least a richer pilot jet. The aftermarket exhaust makes it a bit lenaer too. Use the search function here and you will find the specifices. Depends on where you will be riding it. I keep my bike jetted for about 2500 feet at 80 degrees. Still runs OK in the mountains at 8000 ft, but I might put a bigger main jet if I run it hard at sea level (Glamis, Pismo, etc)

If I remember correctly, it's a size or 2 larger on both jets and a shim ( samll washer .030 thick) under the needle to raise it a bit.

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You should be able to tell that your bike needs rejetted. Is it backfiring? How is your throttle response? When I changed my exhaust I had very little throttle response and it backfired like a model T.

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Now do I have to put the hole jetting kit in it, or can I just put a larger main jet in? I already have three new main jets, 155, 160, 165. If so witch one do I use? :thumbsup: I ride between 2000 and about 6000 ft. Mostly 3-5 thou. ft. And will that run it more rich?

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Now do I have to put the hole jetting kit in it, or can I just put a larger main jet in? I already have three new main jets, 155, 160, 165. If so witch one do I use? :thumbsup: I ride between 2000 and about 6000 ft. Mostly 3-5 thou. ft. And will that run it more rich?

I would go up one size on the pilot (55). You didnt say if you were useing Daves mods. Have you shimmed the needle and drilled the slide ground the tab on the air fuel mix screw?

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When you get the new jets in check the plug for color (nice tan/brown is right) black is too rich, bone white too lean.

The game really begins when you are rejetted and balancing jet size and exhaust size. What you are doing is trying to get the whole circut "pumping" in equal amounts: suck in the right amount of air/fuel mix, completely combust it, then push it out the exhaust without too much back-pressure (some back-pressure is good for the low end but not too much)

I worked through several variations before getting it right. Here's what I ended up with:

2004 XR650L - Jets at 55/158, needle shimmed 0.03", UNI filter, White Brothers E Series with 6 discs and silent core installed, stock headers, pilot screw 2 1/4 turns out, snorkel gone, smog gone, 5/32 slide holes, 14 tooth front/47 rear sprockets, DID gold chain with rivot master link, stock cam, RSW Racing fork brace, Pirelli T21's, Dirt-Bike-Gear fork, bar, rear bags, 200-220 dipstick ave. temp with wings gone, front fender cut 6" off front/holes in trailing edge, 41 mpg ave., 3800' elevation

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