2000 WR400F question

Hey guys I'm new to this suite and I have a few quick questions.. My 2000 WR400F doesn't have a air cleaner box cover, is this an issue? Also when I start the bike the only way I have good throttle response its if the cold start is on. When it is off, it sounds like a lag when I roll the throttle. I'm thinking about taking the carb out and cleaning it. Any help would be great.

Check the AP for a good squirt. If not, check the AP diapghram.

If you do not have an owners manual, D/L it from Yamaha, it is free.

I pulled my carb apart and cleaned it, I'll see if that was the problem, but still wondering if not having a cover for my air box is an issue.

Keep in mind blipping the throttle when bike is on the stand is different then when riding it. You can easily make the bike stumble by cracking the throttle quickly when just sitting in place. When you ride it its a different story. If it stumbles when actually riding then check the accelerator pump squirt timing.

Go to the stickys and check " How to Eliminate the Bog"


Edited by Team_Oatmeal_Pie

Cool I will see how it rides.. Thank you. I still never got an answer about the air box lid.

Edited by Strauser18

Most every one pulls the air box lid, snorkel thing off so the bike can get unrestricted airflow, it should not affect the bike in any negative way.

Thank you... I made an air box cover out of an old plastic lid. And screwed it down just to have a cover...

make sure you have some big holes in their to let the engine get air. The stock box lid has a hole in it about 2"x4".

you can probably google some pics of what stock looks like.

To check the accelerator pump is working properly- Remove carb from bike (or airbox intake) to check if the carb squirts fuel when the throttle is applied. You should see a nice stream of fuel. If not, repair AP.

Set your fuel mixture screw to 2 ~2 1/3 turns out (whatever suits best).

Thanks guys.. I will google the air box pic for the holes. I also had the carb off to clean it and I had a good stream of fuel when I cracked the throttle. I will also check the mixture screw.

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