2000 wr 400 spudders at low rpms

It starts good it pulls good but when im crusing at low rpms it spudders like ba baba ba baba ba baba but if i hit the gas it pulls hard and runs good wt........?where should i start? thanks

Has it always done this or is it a new issue?

Did you try unplugging (not unscrewing and removing) the TPS?

Not sure i just got it this weekend and whats the tps

Ah, I see. TPS = Throttle Position Sensor

You need to spend a few hours and read the owners manual and get familiar with your bike before you try to repair it. After you have read the book a few times and know what is what on the bike, unplug the TPS like I suggested and test ride. Get back to us with what you find out.

If you do not have a manual, it can be D/L from Yamaha Here.

Thanks I will do some reading tonight and get back to you thanks

There's a TPS on the WR400???

Wha??? Why? It's not even fuel injected?!?!?

Yes, there's a TPS. It's the only sensor we have.

carbukeihin4tps.jpg

It detects the throttle valve opening and sends a signal to the computer inside the CDI. "The microcomputer in the CDI unit detects the engine speed and throttle position, thus determining the optimum ignition timing through the entire operating range. In this way, quick throttle response can be achieved according to various riding conditions." (taken from service manual)

I took off the TPS and it still studders maybe a little less.....What next?????

I took off the TPS and it still studders maybe a little less.....What next?????

I hope you didn't remove the TPS.?? You just have to unplug the wire connector going to the TPS. If you completely remove the TPS, you run the chance of loosing power and performance even if it is reinstalled. At least that is what the manual says. Can you clarify?

It would also help to know what mods have been completed, and your jetting settings, if you know them.

If the bike is definitely better with the TPS disconnected (not removed) then that may be part of your problem. Dig out your manual and go through the tests in it. Hopefully, it just needs a small adjustment. Once that is done, re-connect it and confirm the bike is even better now. Let us know.

Yes just diconnected it not removed

Did you pull and clean your jets? My 2000 is extremely sensitive to even the slightest obstruction in the pilot jet and it can happen fast on modern gas.

Not yet but i will this weekend thanks any other problems with the 2000? Does the header pipe at the motor suposed to get red hot when you worm it up?

I guess the header will glow if you leave it sitting but it doesn't need to idle for very long. I am not sure about the TPS when your carb is most likely a gummed up mess. Clean or replace all the jets if you don't know how to ream them out, new plug and clean air filter properly will be a good start.

Thanks Ill let you know how it works

Not yet but i will this weekend thanks any other problems with the 2000? Does the header pipe at the motor suposed to get red hot when you worm it up?

Yes...the pipe will glow red when the bike is idling. This is absolutly normal on the WR..do not worry about it....or avoid looking at it. Either way the result is the same...no problem!

I forgot to sa it has a daja kit on it and the guy said he changed the cam setting to the yz setting not sure what that means...

Thanks for the pipe info.....

I pulled the carb cleaned the jets- Cleand up the spark plug- cleaned the filter- made sure the fuel line was clear- I tried the stock baffle the after market baffle and no baffle and it still has the same problem...........What next

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now