99 WR400 running lean & hot

I have a '99 WR400 that has just started running very lean and hot... in fact the exhaust header turns orange it is so hot and it melted all my plastic over the muffler. It will idle, but it bogs down and stalls when you give it gas. I have had it in the shop a few times and they say that everything associated with the fuel delivery system and carburation is OK, but it still won't run. Now they want to tear into the engine to try to figure out what the problem is. Any ideas before I drop a few more bennys on this or should I just got my losses and upgrade to a new 450?

Sure sounds it is running lean. This can only be from not enough fuel or too much air. Have you checked for air leakage between the carb and the head?

Take the carb apart and clean it thoroughly. Trust me on this.

I have a '99 WR400 that has just started running very lean and hot... in fact the exhaust header turns orange it is so hot and it melted all my plastic over the muffler. It will idle, but it bogs down and stalls when you give it gas. I have had it in the shop a few times and they say that everything associated with the fuel delivery system and carburation is OK, but it still won't run. Now they want to tear into the engine to try to figure out what the problem is. Any ideas before I drop a few more bennys on this or should I just got my losses and upgrade to a new 450?

I have exactly the same problem with 2000 WR400F. What was the solution to this problem? Can anyone help?:cheers:

I think they've been covered, air leak or clogged jet.

I think they've been covered, air leak or clogged jet.

My vote goes for clogged jet.

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