Mystery carb screw...

7 replies to this topic
  • radish150

Posted June 25, 2005 - 11:24 AM


Well, after tearing down and rejetting my 99 carb, i have a screw that I dont now what to do with. its carb grey, about 3/4 long and 1/8 diam with threads all the way up and no head, just a screw driver slot in the end of the screw.


  • ddialogue

Posted June 25, 2005 - 02:10 PM


Sounds like the pilot jet...

  • radish150

Posted June 25, 2005 - 07:03 PM


But there is no hole in it... it´s grey colored too. :) :)

  • MorrisWR

Posted June 26, 2005 - 12:31 AM


Yeah, it doesn't sound like a jet with that color but the threads going all the way up does sound like a jet. I don't have a 99 so can't tell what it might be though. Is it no head at all (ie. the thread go right into the end) or does it have a small round head? If it has a small round head it could be an outside bolt (top of needle cap or drain for bowl). If it's gray, you'd think it might be an external screw but it sounds like you mean no head at all.

I'd look online at someone like Yamaha of Troy that has a schematic of your carb and see what matches. They show just about everything on the carb.

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  • db_010

Posted June 27, 2005 - 07:45 AM


If you haven't already figured out the mystery screw, go to
click on carburetor diagrams
FCR Sidedraft
Could your mystery screw be #18? "Stop Screw" - goes inside a hex nut into the throttle shaft and adjusts the closing limit of the slide. I recently took apart my '99 wr carb and seem to remember this screw fitting your description.


  • db_010

Posted June 27, 2005 - 07:48 AM


By the way - #18 is at the top center of that diagram. Just to the right of the carb top cover that has the "CR" on it.

  • vector6

Posted June 27, 2005 - 08:04 AM


bowl drain screw?

  • radish150

Posted June 27, 2005 - 08:17 AM


Don, yes #18. You ARE the man. Damn factory manual is downright RUDIMENTARY!!! Sudcos diagrams rock.

Mark Sheldon


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