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Discussion Starter #1 (Edited)
Hi all,

Trying to get rid of an occasional but annoying hiccup through the airbox that's been there since I put the carbs on. I went from a 60 slow jet to a 50 and now have some skipping/missing/sputtering at 1/8 to 1/4 throttle. Mines a 900 with open airbox, K&N filter and carbs set up below. Any idea what to try next? From 1/2 to WOT it pulls great. I can send a sound bite if someone will let me know how to attach. Oh, after the change to the 50 while it was running I also closed the fuel screws all the way and it still ran but it wasn't smooth.

Thanks.

fuel screw 1-1/2 out
slow air screw. 1-1/2 out
slow fuel jet. 50
main jet. 155
main air jet. 200
needle EMT clip 3rd from top
 

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Discussion Starter #3
Thanks, I'll get one coming & maybe a 52 or 55 pilot just to have on-hand. Would clip 3 from top be a good place to start?
 

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The best advice I can give you is this ---Change ONLY one thing at a time--Never more then one--change that iten then test--did it get better or worse? then try the next thing--did it get better or worst and continue until you get it right. I am using the original carbs on my 91 900SS but had to rebuild the carbs and used the Factory Pro jet kit--after I had them cleaned and the first set-up I still had to remove the carbs 6 times to get it dialed in correctly-there is no magic bullet every bike is different and of course where you live also makes a big difference
 

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i'd start with the needle in the middle, that's typically where you hope it'll work, maybe 1 up or down from there.

maybe try a 48 pilot, see if it helps. i've found the idle fuel screws to have no real effect with 52 or 55 pilot.
 

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The slow jet meters air. So at 1/4 throttle if you slightly close the throttle does it pick up? If it does then its not metering enough air and is rich. Do this at a higher RPM and 1/8 - 1/4 throttle.
You have two option to verify:
  • Drop the needle 1 clip. WOT the needle is all the way out anyway.
  • Go back to the 60, or get a 55 if the bike picked up like above closing the throttle
  • Also at WOT and steady, if you roll out of the throttle a smidgen, does it pick up RPM? If so then its lean. If on the other hand it doesn't change or if it drops RPM its rich or pretty close.
 
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