Poor Running 2001 XR650L in High Rpms - help!

Hey all! I just purchased a 2001 XR650L w/ 270 miles on it. The only problem is, when you open the throttle all the way it chokes, spits, gags, and all but stops running! It detonates a lot on decel, too.

I pulled off the carb to see if it was gummed up, but it's clean, no clogs in jets or anything like that.

What could the problem be? HELLLLPPPPP!


Is it bone stock or are you running an aftermarket pipe or air cleaner? If you are, check the jetting. Sounds like its way too lean. Is the float working and is the chamber full of fuel? Any (drastic) elevation changes? Check the pilot screw and see if has been moved inward (for low end & idle tuning). Check the air cleaner, check the plug. Spray some carb cleaner in the intake side when running to clean/free the throttle plate. Change the gas to higher octane. These are all easy items to do or check first to see if its something more serious.

I experienced some of these same issues when I installed a new Uni-filter on my 98L. It ran really rough and extremely lean. I bought and installed new larger main and pilot jets, and backed out the pilot screw to 3 3/4 turns (not recommended) and it cured the problems.

Good luck & keep us posted.

I would guess it still has the stock jetting with only 270 miles on it. The L runs like a pig with the stock jetting. :D

The common setup is a 55 pilot jet and a 160 main jet. Remove the snorkel on top of the air box. It's only held on by rivets. Drill out the carb slide holes. Get a UNI filter for it. Get a smog pump block of kit. File off the tab on the air mixure screw so you can turn it more than 1 full turn out. These things really wake it up. :)

Well, I've replaced the plug, and found a carb hose that wasn't attached, which helped the backfiring when closing the throttle, but the high-rpm bogging and spitting continues on.

I'm going to move to a larger main jet as suggested. I don't want to alter the bike all that much w/ so few miles on a very clean unit. I just want it to run at least as well as my girlfriend's stock DR650 PIG does!

I'll continue to keep everyone posted. Thanks for the help! I'll go w/ the 160 main as suggested.


The backfiring is caused by the pair valve (smog pump). For twenty bucks you can get an IMS smog pump block off kit from Baja Designs. Very easy to install. Get a 55 pilot jet from Sudco or carbparts com. It's the "26" series. N424-26-055 Get a 158 or 160 main jet while you're at it. 99101-393-158. Put on a K&N air filter, remove top snorkel, put on 14 tooth countershaft sprocket..then eat DR's for breakfast.

The backfiring is caused by the pair valve (smog pump). For twenty bucks you can get an IMS smog pump block off kit from Baja Designs.

XR's Only also sells one. It is money well spent. That annoying popping will disappear forever.


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