new xr650r help! again

3 replies to this topic
  • perrier

Posted May 20, 2005 - 06:20 AM


Asked previously about how to uncork the brp. Bike mad tim gave some good advice which I took. However the thing is still suffering. Itactually comes stock with the 68 slow jet so I haven't touched it yet. It runs good on top now but it garbles like crazy from closed to about 1/2 throttle. Is it possible that the 68 slow jet is just way to fat and the bottom end is loading up?Also I'm unclear about the carburator baffle to be removed, whats it look like and wheres it hiding? Any advice would be appreciated. Thanks.

  • Max Power

Posted May 20, 2005 - 07:15 AM


Give us a list of all the mods you have done including main jet size and the clip position on the needle.

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  • frankstr

Posted May 20, 2005 - 01:09 PM


replace manifold between carb and engine, Make sure your slow jet is a 68s, not just 68.... :D
And like Max Power said some more info would be nice........ :)

  • smashinz2002

Posted May 20, 2005 - 08:45 PM


The Carb baffle is between the carb and the cylinder. Must be modified or replaced with the 40mm unit.
Even with the stock pilot jet, when properly uncorked, the bike does NOT sputter or act strangely at low throttle openings. The only thing the bigger pilot jet does is help starting, improve low speed operation, and prevent overheating at very low riding speeds.

Do these things to uncork;
1. remove airbox baffle plate and snorkel
2. replaced carb boot with the 40mm unit, or modify the stock unit to 40mm
3. replace stock exhaust tip with 40mm unit, or modify the stock unit to 34mm or 36mm
4. replace stock pilot jet with the 68s, or simply use the stock pilot jet.
5. replace stock main jet with 160, 165, 170, 175, or 180, depending on altitude
6. replace stock needle with the B3E competition needle and set to the middle (3rd position); or, keep the stock needle and set to 4th position (from top)
Optional mods are to drill the airbox with numerous holes to increase airflow. Doing this, keep in mind that increasing airflow means richer jetting and even more open exhaust, for best results.
And never run low grade fuel in it. High compression engines love high octane. I know, I know, the 650R will run fine on 87 unleaded, but, better results are to be had with higher octane, non-oxygenated and high quality fuel such as Avgas 100LL, which by the way is a superior fuel and provides excellent results in the 650R.

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