650R jetting advice?



2 replies to this topic
  • Keo

Posted March 16, 2003 - 08:00 PM

#1

I bought a '00 XR650R from another member of this board a few months ago, and finally decided tonight to tear the carb down and see what was installed in it. I am hoping someone can lend some insight or give me some advice on the setup. First, let me say that before I did anything to the carb, it started ok (kinda difficult in cold or rain) and the power seemed really good off idle. If I juiced it in 1st or 2nd at low revs, the front end came right up. However, It seemed like the top end of the rev range was REALLY flat. Granted, I have ridden sport bikes in the past that make all their power up top, but this thing still feels weak to me. As an example, in third gear at any RPM there is no way it will wheelie with stock gearing on the street. It definitely feels weaker at high RPM than off idle. He told me that the uncork kit was on it, and indeed I did not find anything restricting the intake, and the tip looks to be a large diameter Honda piece, or was drilled out. It is definitely not the little factory one. I also cut 2 large triangular holes in the left side panel to increase the airflow. It still has the factory air filter with backfire screen. That will be remedied soon.

I am in Roanoke, VA at about 1200' elevation in case anyone is wondering. Tonight had light rain and temp is about 55F. Ok, now for what I found in the carb. The main is a 175, with a B53E needle in the middle clip position, and a 65S slow jet. The air screw was 2-1/4 turns out. The needle was visibly bent (is this common?) which I determined not to be a good thing and went about straightening by hand. I think I got it fairly well straight.

I raised the needle (lowered the clip) to the 4th position from the top, and set the airscrew to 2 turns out before I put everything back together. That throttle and return cable assembly is kind of a PITA, BTW. I rolled the pig out of the garage and kicked her over with the choke on. It tried to start and died, so I turned the choke off and kicked again. She fired right up this time (which is pretty comparable to what I experienced before when starting). After adjusting the idle back down to normal, it seemed to idle a little smoother than before, so after a couple minutes I hopped on and ran her down the street. I can't really tell yet how much difference my changes made, because instead of lifting the front, the rear was spinning. My seat of the pants reaction is that it is better now than it was, but I will have to report back on that in a day or two. Also, being so late at night I couldn't really open it up. One of my neighbors is a state trooper.....lol.

Anyway, I know this was a long diatribe abobut an often covered subject, but I am hoping some expert, like Qadsan maybe, can give me some helpful advice on what to try next. My gut says that the main is probably good to go at 175 and the B53E needle is probably ok in the 4th position too, but the slow jet should be a 68S instead of the 65S. Thanks in advance guys.

Keo

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  • stonewall

Posted March 17, 2003 - 04:50 AM

#2

Keo

I am a little higher in elevation than you but here is what works for me. 172 main, 68s slow, B53E needle in the middle position. I think the air screw is 2 turns out. Once you put in the 68s get it warm and fiddle with the screw until you get the best idle. The 175 main was too rich for me. I tried a 170 but the 172 seems to work best. Since yours was bent I would pick up a new needle too. I am definitely no expert so maybe someone else can give you better advice. With stock gearing I can easily pull 3rd gear wheelies and with a hard tug on the bars 4th is possible. Good luck.

  • thumpnwo

Posted March 17, 2003 - 06:46 PM

#3

Keo,

The 175 main is basically for sea level. I also run a 172 main which seems to work the best, 65 slow, B53E in the middle, and 1 1/2 turns out on the air screw. Pretty much stock on the slow and air screw. This is all in conjunction with the intake, open air box, Uni and FMF Q.
My bike is also a Calif. model with the smog removed (don't tell anyone :)).





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