fuel screw adjustments - cold weather

5 replies to this topic
  • skthom

Posted November 30, 2001 - 04:06 PM



OK I'm confused. Just went out to start my bike. It's been sitting since before Thanksgiving. It is much colder since I last rode (75 degrees when I last rode, 50 degrees right now). I haven't done anything since the last ride and the air filter is pretty clean.

Took about 40 kicks to get it going including two rounds of 10 kicks with the compression release.

Once it fired up I had to adjust the fuel screw to get a decent idle. I started with adjusting it in a 1/4 turn and it seemed to run great. I thought cold weather meant a leaner mixture and you adjust it *out*? I had to stop playing since the kids were trying to poke their eyes out w/sharp objects when I wasn't watching....

Any thoughts?


  • skthom

Posted December 02, 2001 - 02:24 PM


OK - kids are quiet now.

Anyone have some more insight here?

At the original position, when "blipping" the throttle, it sounded "starved" for air, not blubbering, just like it wasn't get enough. When I turned it in a 1/2 turn from that position, it started doing the "hanging idle" thing which I know is too lean. When at a 1/4 turn out from there (1/4 turn in from the original position), it sounded and responded great.

Does any of this make sense?

Do you all have similar behavior with the fuel screw?



  • yzfguy

Posted December 02, 2001 - 02:34 PM


i just had to adjust mine also for the cold weather...it started to idle for a extra few seconds and then drop down to normal...i turned it out about 1 turn, and perfect..
i think it just needs to be wherever it idles the best..but you are right.. when it gets cold. it will run lean...

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  • motoman393

Posted December 02, 2001 - 03:41 PM



I live in Houston too and I also havent ridden since before Halloween (due to a concussion and broken collarbone mid October :) ) I started my bike today and adjusted the fuel screw with my new "adjust on the fly" fuel screw...and it is now at 1 7/8 turns out w/42 pilot! I cant wait til next weekend, because I finally get to test out my new revalved/resprung suspension (I would have ridden today, but the rain was too bad as you already know LOL)

BTW this is how I set my fuel screw: First turn the screw in (clockwise) until the bike misses or changes revs (this is making it leaner) Then turn it back out until it misses or revs again (but make sure you count the turns) then put it right in the middle of both far rich and lean. If you have to adjust your fuel screw out further than 2 1/2 turns you need a richer pilot jet (like a 45 or 48)! Maybe I'll see you at the track sometime (if I already havent seen you)! Where do you ride at? Later,


  • skthom

Posted December 03, 2001 - 03:38 PM



Thanks for the advice. I did just what you suggested and found the "sweet spot" between too lean and too rich.

I'v been riding at Splendora. What a great track! The first time I went out there I brought my 3 and 5 year old just to watch. That day I remember seeing a CRF450 and a YZ426 killing it. I saw your post about your crash and recognized your bike as the one who was out there that day! I must have left before you crashed.

Anyway, I'm way below your skill level - just before Thanksgiving I got up the courage to gas it and clear a few of the jumps out there. It'll be a long time before I try that triple! I just got into this sport - I can't break anything now. My wife will kill me!

Anyway, I hope you heal fast and get back out there. You have the riding skills and I (and the others on the board) appreciate your web site and tech notes. Maybe you will get an engineering degree in college and continue to school us and the manufacturers!


Steve T

  • motoman393

Posted December 03, 2001 - 03:54 PM



That is cool! That day I was constantly racing with Greg Howard #6 a local pro on his "new" CR450! I had to show him the 426 still was the beast LOL! Maybe I will see you at the track sometime! We are riding at Splendora on Saturday...I finally get to test out my new revalved and resprung suspension!

LOL I understand about the "no injuries" policy my parents dont want me to end up a retard (from all the concussions LOL) I dont wreck very often, but when I do I normally put on a good show for the crowd :)

Thanks for the "words of wisdom" I am planning on being a Mechanical Engineer, since I enjoy working on anything that makes you think (whether it be computers, web pages, engines, suspension, etc) Thanks,

Garrett Berg

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