2011 WR450 idle problem

My 2011 WR450 was running perfect for 625 miles until I got on I 17 and ran it at 80 MPH for three miles. After I got off the freeway it would not idle like it had for the last 625 miles. If you left off the throttle it would die, if you try to turn up the idle screw to make it idle faster the idle would hang at a high RPM for a few seconds before coming down. I also checked the idle mixture screw and it had not moved, and also tried to adjust it with no improvement. Do you think it could have sucked something into the pilot jet causing the problem?? I have also pulled the choke out to see what happens and it kills the motor instantly.

My jetting is 170 main, 50 pilot, 40 leak and a needle out of a CRF450

No baffles in air box, pee shooter removed, AIS removed and gray wire mod

13-50 gearing with stock chain

2012 head light

Edited by tomerb

Wait until tomorrow, to let the engine completely cool down, and try it again then. If it runs well/decent, but after a short while it starts acting up again, I'd say to check the valve clearances. 80MPH for 3 miles, with 13/50 gearing means that engine was doing some high rpm running for an extended distance. Let us know what you find.


I've had it out six times after that happened and it still idles slow.

You could have something stuck in the pilot jet. It's worth a look. Personally, I run a small fuel filter in the gas line to keep this from being an issue. If you don't find something in the carb, I'd check those valves next. Remember, you have to check them with the engine completely cold. Let us know what you find.


How high was it revving at 80mph?? I only cruise at 60 and have 14/50 gearing

I'm wondering what the spark plug looks like. You might have some high speed glazing or overheating

Symptoms: Blistered, white insulator, eroded electrode and absence of deposits. Results in shortened plug life.

Symptoms: Insulator has yellowish, glazed appearance. Indicate that combustion chamber temperatures have risen suddenly during hard acceleration. Normal deposits melt to form a conductive coating. Causes misfiring at high speeds.

http://www.knight-ri...tips/Spark.html (just the first google result)

I would pull the plug and take a look. This will tell you if your having any internal engine problems, incorrect jetting or incorrect heat range. Any of these can cause the problem you describe after a long high speed blast.

If this dead ends you could have sucked something into the carb and just coincidentally it happened after a high speed run. It just sucks to pull the carb on that bike so I would poke around a little first. Your spark plug will give you a really good indication of your engine health.

I think the problem was no free play in the hot start lever cable. I adjusted it today and it seems to idle good again. I remembered that the idle started to hang at about the 400 mile mark and it was the throttle cable had lost its free play.

That would certainly cause your problem! Glad you got it figured out and fixed!!!


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