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2006 Problem Returning to Idle

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I bought a used 2006 YZ250F late last year.  I put a two tanks of gas through it and then put it up for winter.  So far this year I have had issues with it not wanting to idle.  When I let off the throttle it will idle high.  Sometimes it falls back to normal idle RPM on it's own, sometimes I have to put a load on the engine to get it to drop.  I thought at first it was the old fuel.  Flushed the system, still does it.  I pulled everything apart this weekend to check the valves (0.19 on exhaust and 0.10 on the intake) and clean the carb.  The issue remains.  There are no air leaks that I can find on the intake.  Where should I start looking next?

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14 hours ago, ronbuell said:

Idle screw and fuel screw adjustments, along with partially plugged pilot jet.  Does it have a brass or aluminum fuel screw?

I just took all the jets out and cleaned them.  I do not think the issue is a plugged jet, but I will double check.

I have upgraded to a R & D fuel screw which I think is brass.

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Some people will use a small guitar string to clear the pilot, I use a small wire from one of my wire brushes.  Other people on this forum cringe when I say that.  So disclaimer, those methods my not work without damaging the pilot jet.  Buy a new one if in doubt.

Other thing is slide height / idle adjustment will have the same effect you mentioned.  I had it doing on with an 05 WR, and found it was really sensitive to that.  JD jet kit helped.

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I just had exact same symptoms on a 2006 this weekend.

 

Found a partially plugged pilot jet. Cleaned and put back together and it was better. But still finicky high idle until you load it. Disconnected TPS and issue goes away. Re-calibrated TPS and the bike runs like new now.

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One thing I did not mention in the original post is the bike has a JD Jetting kit installed with the lean needle for my elevation and the small o-ring.

I had a little time today to work on the bike.  I tried unplugging the TPS first.  The problem with the high idle then falling back to normal was not as bad.  It still did it, but not at as high of rpm and it would go back to normal after a few seconds instead of having to drag the rear brake to put a load on the engine.  Engine actually seemed a little stronger, but a quick turn of the throttle would make it bog or almost die.

 

After it was good and hot, I set the idle as low as it would go and then tried to set the fuel screw as directed on this site.  Bike seemed to run a little better, but still has the bog off idle and the high idle issue.  After shutting it off, I checked and the fuel screw is 1/2 a turn out.

 

So I think I have multiple problems here.  Where do I start?  Clean carb again and swap pilot?  Do I need a smaller main jet?

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Pilot - Stock? (I did not change, I assume it is stock)

Leak Jet - 55

Needle - Red 5th clip position

Main Jet - 185

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13 minutes ago, morphrider said:

A 40 leak jet should help with bog. What's your elevation?

500ft

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