Jetting for real(!) cold

Hi, from frozen Moscow

What do you use for 5F(-15C), 14F(-10C)?

Pilot air jet

Pilot jet

Pilot screw

Main jet

Main air jet

Jet needle , groove position

Starter jet

PS: I know the carbs are different for different markets

(US, Europe, etc.), but i hope your information will help me

with my games with jets.


if you have a euro wr400f? :) then i would suggest that you go with my jetting from below but that you keep the very rich choke jet in to get the bike started. so a #62 or a #65SJ is fine.

once the bike is up and running the jetting figures below will run the bike at a good 'normal' temperature.

if i were you i would cover at least 50% of the radiator as an experiment. this should give you a good operating temperature.

how to tell?

well generally i would tell when i've STOPPED the engine. the click-click and clack-clack of everything cooling down. if it's hotter than normal; expose more of the radiator than before etc etc


I forgot to say, i've got euro WR426'01,

but i see your main idea about very rich choke jet and

'normal' jetting for the rest. I'll try and post my results

Thank you, Taffy

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