XR 650r Jetting

[HOMBRE]

2002 xr650r

Un-corked, pro circut t4 pipe

Runs great at high end, but considerable backfire on deceleration, inconsistent idle, and hot starts require choke.

Un-educated consensus it that its too lean.

Any expert advice on how to proceed? raise the needle? increase main jet size? increase slow jet size? pilot screw adjustment?

Any advice appreciated. thanks

 

[biglou]

Definitely sounds lean to me, too. Popping on decel is a lean pilot circuit. A little popping is optimal tuning, I'm told. I'd say bump your pilot up one from whatever it has now, and set your pilot screw at 1.5 out. Make adjustments in 1/4 turn increments from there and see how that goes. If you wind up at more than 2.5 out, go up another on the pilot. On my 2001 426, it liked one size bigger pilor when running the Big Gun Race Series pipe as compared to stock. I suspect there is a considerably larger diff between stock XR and stock YZF to aftermarket change, however.

 

[OnAnySunday]

Uncorked? Did you rejet after changing the intake manifold, and removing the airbox restrictors?
Stock jetting is 65s pilot, 125 main. (painfully lean)
Most pigs (650r's) do well with 68s pilot, b53e needle (not nessisary but it comes -w- the kit....), and anywhere from a 170 to a 175 main. (some crazies closer to sea level say a 180 works great.)
Although this is when using the stock Honda muffler -w- the uncorked (power-up) insert.
Mine has a small stumble after landing a jump (good thing i dont jump much. hee hee.), but it starts sooo incredibly easy that i find myself giggling sometimes.
Only bad thing is it sorta ticks off the guys that go through "the routine" with those 250 & 450s to get their bikes started.
I just flick out the starter, find tdc, then give a half hearted kick (whilst sitting no less) and she fires right up.
Then i gotta endure those evil stares...... :laugh:

 

[pontiac]

Try this site for jetting info as a starting point :thumb:

http://www.xr650r.us/jetting

 

[HOMBRE]

Hey

Thanks alot for the info. Pontiac, that site is excellent. Gives me a good place to start.