?adjusting the idle on the '01 426

6 replies to this topic
  • 78sharpshooter

Posted February 22, 2006 - 09:39 PM


I was trying to adjust the idle using the black thumb screw and there was a lot of resistance while turning it. The idle didn't change as I was turning it couterclockwise then all of a sudden the idle jumped way too high and I had to kill the engine. Is there a reccommended way to go about adjusting the idle on this bike? Thanks

  • DTYZ426

Posted February 22, 2006 - 10:24 PM


this has happened to my 01 426 too. I found that the best way to set the idle speed is to start the bike, warm it up to operating temperature, adjust the fuel mixture screw for the best throttle response, then set the idle speed. Do in this order and you should work out the problem.

also, erratic idle speed can result from an intake leak, probably a loose or out of position intake hose clamp

good luck

post your results


  • grayracer513

Posted February 22, 2006 - 10:36 PM


Get a penetrating, dry film lube such as the type for use on exhaust heat valves on cars. Remove the cover on the right side of the carb and lube the threads of the idle speed screw. The operation will be much more to your liking.

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  • dsconstructs

Posted February 23, 2006 - 07:18 AM


Me also, my screw will turn easy enough but it doesn't seem to change anything and then suddenly the idle will jump up higher than I'd like. Trying to lower the idle does pretty much the same thing, suddenly dives back down also. And yes this is while fully warmed up. Otherwise the carb seems to be operating well.

  • grayracer513

Posted February 23, 2006 - 07:47 AM


That situation indicates a lean condition. It may simply be that the fuel screw needs to be backed out a little. Use this procedure

If that doesn't help, look for an obvious air leak around the carb isolator, etc. If you find nothing, check your valve clearance. Tight intakes will cause a "hanging" idle condition.

  • SoCal WR426

Posted February 23, 2006 - 09:11 AM


I agree with GreyRacer, before you do anything complicated clean and lubricate the idle screw on the exterior of the carb. The knurled black knob you turn has a spring and if the screw is gummed up turning the knob does nothing until it overcomes the resistance of the dirty screw and then since the spring has tensioned itself the whole thing turns alot at once and jumps the idle up. This is why turning it counter clockwise does not have the same effect (the spring is not tightening up). Good luck

  • 78sharpshooter

Posted February 23, 2006 - 09:38 PM


Thanks guys. I followed the protocol from the link and it worked great. I used my new inductive tach and found that before adjusting the idle the RPM was between 600 to 700!!!! Before today I thought the throttle characteristics that I was experiencing were just the way the bike is......but now that the idle is in spec the bike seems more normal. The bike even sounds better!!! Thanks again for the direction :thumbsup:

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