carbs and jetting for dummies

2 replies to this topic

Posted March 24, 2003 - 10:52 AM


I read about all this jetting stuff and it intrigues me. But I am not the best wrench west of the mississippi. I can figure it out from the manual but thought since many have done it I could get some pointers.
1. This is a 99wr 400 w/ a 426 pipe usually unplugged, snorkel thing removed but not the whole lid. Kouba style adjuster on the PJ?
2. Bike seems to run great except I get some pop on the decel. A half turn on the pj srcew helped. It was ok but rode this weekend in the rain and cold and it seemed worse.
3. This is a bike I bought used and original owner was not sure of the jetting. So I think there is no time like the present to check what is in it. Baja designs recommended a 48 PJ and 175 Main.
4. Most riding is between 2 and 6 thousand feet with occasional trips above that.
5. What are the steps to check and/or replace jets. Do you have to remove the carb from bike like the manual suggests or is there a trick.
6. I am in north california so if anyone has any recommendations for this bike let me have them.

I know there is probably something else that I am missing so if anyone knows what that might be add it in.

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  • ThumperWR450F

Posted March 24, 2003 - 11:25 AM


i don't know about the 400's and the 426's but on my 450 i just unbolt the carb from the motor and the airbox and tuck the airbox hose behind the frame and i can lean it out enough to get the bottom of the carb off.i can change my jets in like 10 minutes.

  • Oasis_Flame

Posted March 24, 2003 - 07:51 PM


At 4000ft. I'm useing a 162 main with great results. Also useing a YZ pipe. Rest of carb settings are bone stock and plug has a light brown color. Spark plug is now 2yrs. old and I can start the bike on two kicks cold and one hot. I never have to use the hot start knob. 2000 WR400 converted to a 426.


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