Jetting Change ...Hard to start now.

2 replies to this topic
  • Yak

Posted August 01, 2002 - 05:15 PM


I just changed my jetting for the first time, Once I figured out that I could just rotate the carb it was really easy! Anyway, I went from Stock jetting (162,42,4th) to 158,40,3rd. I ride at 4k-6k ft. Problem is now its really hard to start, it always makes the noise like its about to fire, but only does when I fidddle back and forth with the choke out/in. Also, it seems to backfire on certain occasions. Should I go back to stock jetting? and leave the needle at 3rd position? I had a stumble/bog when shifting gears which led me to redo the jetting to begin with. But its just too hard to start now, why?

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  • Fastest1

Posted August 01, 2002 - 05:39 PM


Return it to the way it ran last. Then analyze where that stumble is. Dont just change all the variables at once. There are great sites here regarding jetting. The pilot screw should control right off of idle, then the needle takes over for the midrange, and the main jet controls the top end, though they do overlap slightly. Is this stumble as you are letting off when you shift? or is it as you accelerate into the next gear? If it is during acceleration I would only thought you should have lifted the needle one groove first and seen the results. It is a tedious process and be patient. Good Luck

  • Kirtwell

Posted August 02, 2002 - 07:27 AM


I agree with Fastest1. I just rejetted my bike last week. I did the Bk mod and ended up with 158/42/4. The air/fuel screw out 1 turn.
I played with the jetting a little at a time. It took me several days to complete it because I'd make a change and then ride it hard...then compared the difference.
The bike runs excellent now but I too noticed it doesn't start as easy as before.
Please make sure your carb is not loose in the rubber boots. I had that problem.

Take notes on what you do and write them down to include that days temp and humidity. It will help next summer if you have to do it again.

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