Amount of adjustment on pilot screw

1 reply to this topic
  • Shawn_Mc

Posted January 28, 2002 - 04:42 PM


How much adjustment is actually in that screw? In other words, is the screw still metering fuel beyond 2 turns or is it basically wide open? I was playing with mine over the weekend and it seemed like that past 2 turns the screw had no effect on the adjustment while the bike was running. My pilot is stock, and it seems like the bike wants more at idle. My thought about this is maybe the screw was never intended to be more that 2 full turns out, which may have caused the fuel screw to fall out simply because it was barely hanging in there in the first place like what happened to richb.

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  • Boit

Posted January 28, 2002 - 05:23 PM


You are thinking along the right track. If the adjustment range of the fuel screw falls outside of the ~1 to ~3 turns, then a different pilot jet is called far. Like you describe, if turning the screw beyond a certain number of turns out has no effect, then you've found the effective limit of the pilot screw. Assuming that this circuit is clean, if you find that you need to turn the fuel screw out more than about 3 turns to acheive the desired effect, swap the pilot for the next richer one. By enrichening the jet one step, you should be able to compensate with fewer turns out on the fuel screw. Personally, I think this is a very beneficial learning experience for tuning. You get the opportunity to compare how the engine responds to these changes. If you DO decide to experiment with these changes, give the engine at least 20 minutes of running time to let it reach equilibrium before you make the next adjustment.

[ January 28, 2002: Message edited by: Boit ]

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