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Fuel mixture screw?

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I have a 1975 xl250, went through the carb, put it back together and whenn I try to adjust it the fuel mixture screw has no effect (no change any way). The bike idles fine but is running lean, bogs out at around 3800/4ooo rpms (when I choke it will rev up and threw correctly). I can goose it up past that and up to red line but...??

 

Anyone?

Edited by Licks

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If the fuel screw is not working,either you:

  • Have the idle speed to high when trying to set it
  • Expect it will do anything other than fine adjust the idle mixture
  • The screw is bad or missing parts (spring/washer/oring)
  • Clogged pilot jet
  • Clogged slow air passages
  • Vacuum leak.

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If the fuel screw is not working,either you:

  • Have the idle speed to high when trying to set it
  • Expect it will do anything other than fine adjust the idle mixture
  • The screw is bad or missing parts (spring/washer/oring)
  • Clogged pilot jet
  • Clogged slow air passages
  • Vacuum leak.

 

What he said. If the air screw parts are all good, go up one size on pilot jet and test.

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Thought I would get an email telling me I had a responce, sorry I'm late to my own thread. 

 

I have had the carb apart and It is clean clean. The bike was running Hot but conversly running rich as well. The bike has good compression (210) I have come to question weather the cam is set correctly, I am just not confident where the mark is. When I line up the T mark on the fly wheel with the mark on the case, I am not sure what to look for on the cam. SHould'nt the mark on the end of the cam be level with the head?? and is that mark/line on the cam visable with just the points cover off?? 

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