04 WR450 decided not to run anymore?

Ok, I think I have looked at it all but I'm sure I have not.

Bike was running and warming up, I go to get on her shake her around a bit. Habit to make sure gas is evenly distributed and she is up to idle.

Bam! she shuts down and will not start right after I shake her up.

So the first thing I think the carb has dirt in it and it's clogged.

I pull the top cap pull the needle check all that good to go.

I pull the bottom plug an only a little gas came out, thought that was odd so I pull the float bowl and check that to make sure nothing is stuck all free moving parts.

Pull the main jet make sure it's not clogged, all looks good.

I crank the throttle open and the slide moves up and down.

I check the battery good to go in fact I have kept the booster on it just to make sure.

I take apart the kill switch to make sure that is not being stuck some how.

I hook the gas tank back up open the float bowl plug and no gas drains through... My buddy told me as long as the gas is on it should come out of that float bowl drain all day long until I close the gas or close the plug... NOTHING! no gas! Is what my buddy telling me true for these bikes? I have to assume yes as my buddy is almost always spot on or very close with his information. Anyway I check spark, with a real tester, good. I spray either in the carb and she will fire so I'm thinking not getting gas....

What should I be looking at next?

Gas comes down the tube that goes into the carb but for some reason no gas is draining out of the float bowl plug when I keep it open. So it's like my carb is not taking in gas for some reason.

Your buddy is correct. If gas flows out of the tank's hose without being hooked up to the carburator, then it gas should continue to flow out of the drain plug when the hose is hooked up to the carborator.

It sounds like you float valve is stuck shut for some reason. Take the float bowl off of you carburator and inspect the floats, the float valve, and the linkage connecting these two parts. Your float valve is a small brass needle that looks like a tiny pencil. There will be a tiny screw that you have to remove to get to the float valve.

Check out the link below and look up a 2005 WR450 motorcycle. Then click on the carburator link. The parts you want to inspect are #25, 26, & 27


I see so just checking to make sure the float moved up or down was not enough...

I'll look into that a bit mroe tonight...

He said float all the way I just didn't know what to look for and thought if it was moving up and down everything was AOK....

I'll report back with my findings....

One other question:

If I fill the bowl with gas I should be able to run the bike, correct?

The shots of either got it running for a second or two.

I just want to make sure it will fire and run if I fix the gas flow issue.

Maybe I missed something, but I'm not sure you said fuel was coming out of the tank hose while disconnected from the carb. If it is, continue as directed above, but if it's not, maybe your gas cap vent is blocked. :excuseme:

I just picked up an 04 that sat since the fall of 04 and it had the same problem. I found two things; #1 the fuel filter on the end of the fuel pickup (end of the petcock) was filled with crud and #2 the tube that comes out of the carb that the fuel line attachs to was filled with crud. Cleaned everything out and she runs like a raped ape :excuseme:

I checked the vent hose on the gas cap but I did not check the over flow hoses and stuff.. thanks for the info on that.

Yes, the gas does seem to flow through the petcock thing and through the hose that goes into the carb it just does not flow though the carb.

What is the best way to take the carb completely off the bike to clean it?

Meaning I have everything disconnected but the throttle cable and stuff..... It looked intimidating to a guy that has done nothing but jet the thing a few times, change the oil and change over tires each winter to spikes.

I took the cap of the throttle body thing, the same thing I did to do the YZ throttle pin free mod. Do I disconnect from in there? it looks like it's all spooled up and impossible to take off. I know I'm not seeing something or am I?

Careful with the float bowl screws, they strip real easy, needle nose vise grips will get them out and then it's a trip to Home Depot where you can get an allen head equivelant, (can't remeber the size :excuseme: )

Good luck, I 2nd the float valve issue :bonk:

I took the cap of the throttle body thing, the same thing I did to do the YZ throttle pin free mod. Do I disconnect from in there? it looks like it's all spooled up and impossible to take off. I know I'm not seeing something or am I?

If you release the throttle cables from your throttle (on the handlebar) it will give you enough slack in the cables to remove it from the "spool".

Don't forget to unscrew the hot start plunger when your taking out the carb.


Thanks, yes looked at the hotstart plunger to make sure that was not stuck open or closed during my analysis of the problem. I notice I didn't mention that above.

Have that still removed, just wasnt sure on the best approach with the throttle cables.

Sounds like I need to go through the carb with a good cleaning and start fresh from there.

Many thanks.

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