Throttle Valve Problem

6 replies to this topic
  • Cairn

Posted June 04, 2005 - 03:52 PM


I am a new WR450 owner doing the free mods. I am not a mechanic! In the process of swapping a JD needle for the stock needle, I raised the carburetor slide "to the top" for easier access to the needle. When I did this, the top of the throttle valve came up over the top of the carburetor housing and froze. It will not drop back into place and the throttle movement has no effect. When I checked the throttle stop, I found that it was missing. I am assuming that because of this, the throttle valve opened up more than it should have, causing the problem. Any advice on how to get my carburetor back together would be appreciated.

Thank you.


[COLOR=Magenta]Solution: Turning the throttle enough to free up the "push rod link lever assembly," then pushing the lever, frees up the throttle valve. The valve may not drop, however, if the jet needle is not aligned properly. Finally, the throttle valve lever rollers need to be aligned with the slits in the throttle valve, which is as straigtforward as it sounds. My thanks to PNWWR400 for coaching me through this process. :)[/COLOR]

  • Cairn

Posted June 04, 2005 - 08:33 PM


Is there a better place in the forum to post this request?


  • pnwwr400

Posted June 04, 2005 - 09:39 PM


I did the same thing it frewaked me out, thought i broke the carb etc. My carb had the throttle stop missing also. I don't think its why you had trouble. IMO its because the top of the carb was off allowing it to raise higher than normal.
I believe what did was : on the side where the throttle cables ends attach to the wheel is a arm(below the wheel) that you can raise/release with your finger or a screwdriver. This should release the slide which should go down. Now when i change jets i make sure i only raise it 1/2 way and use needle noses to get the jet needle out. I think i had the carb off the bike when i discovered this. If you still have trouble e-mail me, i give you my #
Good luck

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  • Indy_WR450

Posted June 05, 2005 - 03:32 AM


You most likely cut your throttle stop down too much. The slide should just open fully in the carb throught as it hits the stop. Do not ride your bike like this. It is very dangerous. :)

  • Cairn

Posted June 05, 2005 - 05:03 AM



Thanks a lot for the advice regarding what appears in my manual to be the "push rod link lever assembly." I'll give it a push later this morning and see if that does the trick.

Note Indy's comment above. I think that the problem occurred because there was no throttle stop. Did you install one on your bike after you discovered that it was missing?


  • pnwwr400

Posted June 05, 2005 - 09:22 AM


From my time viewing on this board indy is the man. My bike has not had a throttle stop since i bought it 10-04. My opinion is the carb slide is safer to work on with the yz throttle stop, maybe i get one soon!

  • Cairn

Posted June 05, 2005 - 10:43 AM


I have played around with the push rod link lever assembly, hoping to free up the throttle valve, but it did not drop back in place. Wiggling the throttle valve assembly and applying light pressure does not help. There is definitely something keeping the throttle valve assembly from falling back into place, but I'm at a loss to know what it is.

Any other ideas???


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