1998-WR400-Idle probleme

Hi every body, just buy a new WR400 1998 the bike run great at hi RPM but it dont keep his idle :thumbsup: I have clean the carb. put everything at the shop manuel specs needle at position 4 the main jet is 168 and air screew at 1 3/8 I cant turn more my idle ajustment it at is maximum !!! Any idea ??? any help will be appreciate. If I put the chke the bike run very fast maybe 4000rpm.


Lot's of problems with early FCR carbs and idle circuits. They get corroded easily and are extremely difficult to clean. Also check the throttle slide to be sure it is not cracked, another early carb problem.

Any other idea ??????? any fix for early carb problem ??

try turning the fuel screw(airscrew out aproximatley 2-2,1/2 turns

My yzf was 2,1/2 turns out.

When i have it at 1,3/4 as the manual says, it doesnt idle.

Good I will try it and give you some news....

:thumbsup: :thumbsup: :busted:

Ok I have play whit fuel air screw I have improve the idle but to many hesitation now until 1/4 of the trotle, and when its at idle speed if I turn the trottle fast the bike dead.


Do you have trouble to ride your bike whitout the TPS pluged ?


Other point: If I buy all the gasket for the carb,a new accelerator pump diaphragm and a new tps the total cost more than a new edelbrook carburator. Whit the edelbrooke carb does the performance of the bike is improve does it run smooth ?? difficult to ajust?

I picked up a WR400 a few months ago. It was unhappy starting, at idle and would die when backing out of the throttle in tight going.

Check your accelerator pump diaphragm ( in a bike of that vintage, I'm certain it's trashed as mine was,) get your mixture screw at the factory setting and adjust your TPS and it should run great.


Your stall off idle sounds like a plugged pilot jet. Check it one more time, it has very small passages. I finally changed over to an Edlebrock Carb for the same reason you state. Happy with the Edlebrock.

Thank you very much really helpful for me I will to a doudle check on the carbs and yes the first time I have clean the carb the accelaration pump was jamed and full of shi.... the little shaft was so rusty it was jamed.... I have freeup everything but maybee it need a new acc. pump diaphram....

My 1999 WR idle scew was not pushing on the lickage, it was behind hence no idle. I bent it back and now I have idle and adjustment.

I have fix my probleme, I have receive my new edelbrook card......man all my carbs probleme as gone..... 15 minute for install the edelbrook carb first kick and the bike run like a new..... no idle probleme start at first or second shot HOT OR COLD..... man I dont know why yamaha cant do carb like this....the new carb come whit new pull and push cable. Just for rebuilt my old carb whit a new tps its cost more than the new edelbrok carb.

here are the price of the parts here in Quebec:

replace all the jet $85.00

new pump diaphragm $98.00

new push rod for acc pump $20.00

new push and pull cable: $60.00

new TPS $265.00

And you know what.....you are alway whit an 1998 old carb. If you have major probleme whit your carb I recommand to every body who dont have time to wast whit adjust and tune your old carb to buy an edelbrook carb. For the rest of the peoples who prefere to crank our bike during many minute.......this is your choice, I can tell you this is the best $350.00 mod on my bike.


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