sooty xr 650r

5 replies to this topic
  • GRAHAM25

Posted September 03, 2004 - 07:24 AM


Hey gang,

I have a 2002 xr 650r which I uncorked and replaced the jetting and needle per Honda racing recommendation. 175 main 68s and 53e or f needle i forget which was stock (middle position). My exhaust is very sooty.I've adjusted my mixture screw 2 to 2 1/2 out and it runs leaner but still isn't right. I took it by a local shop and he said to put the stock needle back in and he recommended a 145 jet. I made the change and the bike ran leaner but it didn't have the power :thumbsup:. I went back to the honda race set up but I can't get rid of the sooty exhaust.I'm @ 900 MSL.

Any ideas? Or is that how the XR 650 is uncorked with this mod.

Thanks ALAN

  • Portland_650R

Posted September 03, 2004 - 11:44 AM


I've had a bit of soot too... bike runs great, no visible black smoke. Just some soot. The plug is slightly looking rich but I would rather err to that side of the scale. If you're just talking about it being on your pipe, I wouldn't worry about it; if it's black smoke - one thing I did notice was that you didn't mention float level - is that set right?

  • qadsan

Posted September 03, 2004 - 02:15 PM


What altitude & temperature are you riding at?

Did you change out the intake manifold for the HRC version or cut out the restrictor plate in the stock intake?

Did you also remove both of the airbox restrictors?

Are you still running the stock exhaust tip or did you drill it out or buy the HRC tip?

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  • Old_Man_Time

Posted September 03, 2004 - 08:24 PM


I always had better luck with the 172 main. I use the 175 when I am at 1000 to 2000 feet above sea level. It is a bit sooty but the power difference is noticable and it didn't smoke black. The plug looked like it was running Rich. Still the pulling power was noticable. The 172 just seemed to run cleaner and crisper.

I now don't use jets, just an Edelbrock that is always fowling up on me but when it runs right its really nice.

  • GRAHAM25

Posted September 04, 2004 - 02:52 AM


I have updated the intake to a 40mm,taken out the airbox restrictors, and drilled out my stock tip. I'm @ 900msl 70-85 in the summer and high humidity.

  • qadsan

Posted September 04, 2004 - 07:06 AM


As a starting point, I'd suggest trying both a 168 & 165 main jet, the B53E needle on the 3rd clip while also trying the 2nd clip and your 68s pilot jet should be just fine. Try the main jet swap first since it's the easiest & quickest to do. High humidity causes the engine to draw a lower percentage of oxygen during the intake stroke (water molecules are displacing the oxygen molecules), thus making your air/fuel mixture richer, so the course of action would be to use smaller jets to lean it out a bit more. I think you'll find the best top end performance with either the 165 or 168 main jet for your specific environment.

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