CRF's Only Forums

hey all, new to this forum!
I've read through the sticky on rejetting these bikes(and other forums), I'm wondering if this is applicable to riding at an elevation of 900ft. I'm pretty sure that's the elevation of north texas. so far I've debaffled the exhaust as well as removed backfire screen, removed snorkel lid and also put a hiflow air filter on it as well. it is a stock 09 carb. just so I'm understanding it's a
115 main
42 pilot
how many turns out on the A/F screw on the bottom of the carb?
also it gets fairly humid some days in summer highs in the low 100s and winters with windchill can be in the teens. bike cold natured if you start it up and blip the throttle at a 1/4 she cuts out and dies. however she does start without th choke now( turned the A/F screw on bottom almost 3 turns out). I'd greatly appreciate any and all input and suggestions

Welcome to the site !!

Hopefully Leardriver will chime in soon , he is the forum Intake/Jetting specialist ....

Welcome to the site as well.
Since you are almost 3 turns out on the fuel screw you really need to go up at least one idle jet size.

At around 3 turns out you run a risk of the screw actually unscrewing further and falling out.

If you do have a 42 idle jet then changing to say a 45 should improve the cold blooded response.


I find that temperature and humidity swings do make small changes to jetting but is mostly felt at idle.

Welcome to the site as well.
Since you are almost 3 turns out on the fuel screw you really need to go up at least one idle jet size.

At around 3 turns out you run a risk of the screw actually unscrewing further and falling out.

If you do have a 42 idle jet then changing to say a 45 should improve the cold blooded response.


I find that temperature and humidity swings do make small changes to jetting but is mostly felt at idle.

right on, yeah I've ordered a air fuel screw with the Tee from this site, trying to tune that without it is a pain lol I'd rather not pull the carb just to make a small adjustment, I got fat finger so theres no room for that and the tool together lol other then that it runs pretty dang good, just wanna get the most out of this little pitter and it breathe and drink right so that's why I'm asking about these jetting specs, I've seen alot of folks using that specific jetting but wasnt sure about their elevation, still trying to figure out the whole jetting aspects of bikes

The 900 feet won't make much difference so not to worry about.
I find winter to summer you will need to adjust idle slightly and I have adjusted the main down a size in summer from the winter setting but I was probably as rich as on my winter setting at that time.