450F 2003 WR450F issues

[MY-BLUE-BEAST]

My brother has a 2003 WR450F, lately it has been acting up and having a few issues.

1st: It is crazy hard to start, after about ten or so hard kicks it finally starts. Electric start, Forget about it.

2nd: once it is started it runs crazy hot. Just sitting on the stand running for about 30 seconds it is already red hot.

3rd: It doesnt idle, the adjuster doesnt work, the fuel screw doesnt work, it just wont idle.

Here is what we have done:

1st: We checked the valve clearances, no issue there, they are perfect.

2nd: Cleaned, cleaned and cleaned the carb still nothing

3rd: Rejetted from stock jetting and up and stock jetting down, trying every jet imaginable.

The plate on the front of the throttle slide is in the right spot, the timing is dead on.

Is there anything we are missing? I am going to pull the carb off of my bike and try it in there just to see if it works, if it does then at least we narrowed it down. What do you think? Im already sick of the damn thing, and would appreciate the help. Thanks

 

[SRAD97750]

Yeah, I'd go with the carb swap just to see if that fixes the issue, rather than chasing the random guesses I would give you. Give us a holla about how it goes. -BIG DAN

 

[2strokesteve89]

The running hot thing......is it the exhaust pipe that's hot, or the engine, if it's engine, I'd be looking for a head gasket issue, or maybe ign. Timing....if it's exhaust hot, then sounds like it's running lean at idle.i know you checked some of this stuff already, but if I was checking it, that's where I'd start. Also if the air/fuel screw won't work then either the passage Is plugged or there is a vacuum leak.

 

[MY-BLUE-BEAST]

The running hot thing......is it the exhaust pipe that's hot, or the engine, if it's engine, I'd be looking for a head gasket issue, or maybe ign. Timing....if it's exhaust hot, then sounds like it's running lean at idle.i know you checked some of this stuff already, but if I was checking it, that's where I'd start. Also if the air/fuel screw won't work then either the passage Is plugged or there is a vacuum leak.

The motor is hot. But we got her sorted out. It ran perfect with my carb on it. So we started swapping parts from one carb to another and found out all we needed. Turns out the poor carb is worn out. Once I replace a few parts the old girl will back to its original glory.

 

[MY-BLUE-BEAST]

Acording to one of the service guys I work with, I need to replace the following numbers

10 throttle slide wheel
12 throttle plate seal
18 and the needle nozzel

What do you think?