07 yz 250 cold weather jettting

[Yamaha4lyfe]

07 yz 250 on stock jetting

about 1000-1500 above sea level

it seems to be reving awkward when i clutch it. sort of like the sound when you forget to turn your petcock on, when its almost out of fuel but doesent progress. im guessing its running lean it does run very crisp when shes wide open though haha. do i need to provide the jets that are on it right now? or can someone tell me what i need. its about 0-10 degrees Celsius any kind of help on this subject would be most appreciated. thanks again

Ryan

[Yamaha4lyfe]

bump!~#@!@#@!#!@#@!#@!#

[yathump]

Yes we need the current jetting, as the temperatures get colder you need to rejet richer

You say it does it when you clutch it so is it when the rpms are low?

Have you tried adjusting the airscrew(turning it in to richen the mix)?

[Yamaha4lyfe]

i kinda turned it a bit but not noticeably . would turning it in richen it up? ok ill get the sizes that are in it right now. and ill post them asoon as i can it also sputters and such when i let off the throttle at high rpms thanks

[Yamaha4lyfe]

the plug looks good to me threads are wet and black electrode is dry and looks the same way as it went in, and the porcelain is a light brown and dry. does that mean my jetting is still good? or to lean? im running a 30-1 mix and this is on 2 week old fuel.... have a race this weekend in the mountains and i dont want a seized engine

[yathump]

the plug looks good to me threads are wet and black electrode is dry and looks the same way as it went in, and the porcelain is a light brown and dry. does that mean my jetting is still good? or to lean? im running a 30-1 mix and this is on 2 week old fuel.... have a race this weekend in the mountains and i dont want a seized engine

Reading the plug(doing a plug chop to see the base of the porcelain for color) is only for checking the mainjet, the airscrew/pilot-needle/clip position is more of the by feel method. The airscrew is something that is of consant need of adjustment, temperature changes from morning to afternoon will affect the way a bike runs aswell as going from sea level to 2000ft above, the higher you go in elevation the leaner you can go

[elko6]

turning the air screw in will richen it but if you are running stock jets then you will probalby need to run the next richer pilot jet and maybe the next richer spot on the needle at that temperature.