Air/fuel screw question


5 replies to this topic
  • CO_Rider

Posted January 10, 2008 - 12:19 AM

#1

How far should you be able to screw in (lean out) the air/fuel screw before the bike will shut off? Mine stays running all the way until I screw it in all the way then it will finally shut off. Sound right or am I maybe 1 size off on the pilot?

  • hyperlite33

Posted January 10, 2008 - 10:16 AM

#2

Played with this a little trying to figure out my pilot circuit also...

http://www.thumperta...ad.php?t=327405

Hope this helps!

  • CO_Rider

Posted January 10, 2008 - 12:47 PM

#3

Thanks. :banghead: I actuall saw that post and is the way I am trying to dial it in but really didnt know if it was supposed to shut off and if so when. Honestly the bike runs real strong now so I shouldnt even be messing with it but I guess I was just curious.

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  • William1

Posted January 10, 2008 - 01:54 PM

#4

Fuel screw is for idle only (mostly) set it to the perscribed procedure. If the exhaust is popping, try opening it a little, no more than 12/2 turn.

Fuel screw settings in the 'book' are recommended starting points. Every bike is different, as is the temp and altitude. Set the screw according to this method.
Gently turn the screw all the way in. Now back it out two turns. Start the bike and fully warm it up, go for a 10 minute ride. Set the idle to speed to 1,500~1,800 RPM as best you can (I know, without a tach this is tough, just set it to were it idles relatively smoothly). Once warmed, slow the idle to the lowest possible speed.
*** When turning the fuel screw, keep an accurate 'count' of the amount you are turning it and record it in case you have to reset it for some reason. Makes life easier when you can just set it from notes Vs. going through the procedure again.***
Turn the screw in until the idle becomes rough or the bike stalls.
if it stalled, open the screw about 1/4 more turn. Restart it and slowly screw it in till you can just perceive a change.
If the screw can be turned all the way in and the bike still idles perfectly and does not stall, then you need to go down a size in pilot jet.
Now very slowly, open the fuel screw till the idle is smooth. Blip the throttle, let the bike return to an idle, wait say ten seconds. Confirm it is the same smooth idle.
If the screw has to be opened more than 3 turns to get a smooth idle, you need to go up a size in pilot jet.
If you find it does not stall with the larger jet but has to be open more than three turns with the smaller pilot jet, put the larger one in and set the fuel screw at 1/2 turn.
If the idle speed increased, adjust the idle speed knob to return the bike to a real slow idle speed. You must then re-visit the fuel screw. Keep doing this till the fuel screw is opened just enough to provide a nice steady idle at the lowest possible RPM. Once this is done, increase the idle speed to the normal one for your bike, typically about 1,500 rpm, but go by the spec in your manual.

  • CO_Rider

Posted January 10, 2008 - 02:14 PM

#5

Thanks alot William :banghead: I will use this procedure :busted:

  • Wes Woodin

Posted January 12, 2008 - 03:37 PM

#6

How far should you be able to screw in (lean out) the air/fuel screw before the bike will shut off? Mine stays running all the way until I screw it in all the way then it will finally shut off. Sound right or am I maybe 1 size off on the pilot?

All the way in.





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