Can't get my bike to run

Just picked up an 04 wr450,

Got it for cheap.

it ran fine but when it warmed up it would sort of hiccup and keep going every few minutes.

I don't know a lot about dirt bikes so I was going to get my friend to check it out when I go back to be next month. I looked through the forums here and couldn't find much that helped with that.

so I decided to clean up the bike.

Took the seat and tank off, cleaned and oiled the air filter, changed the spark plug (it was all black on the end), and put a new coil in it. I tested the coil and it was out of range so I changed it.

I go to put some if it back together to fire it back up to warm it up so I can change the oil... and nothing.

The most I could find out on this forum was I could have flooded it, so I leaned it over and drained the carb, kicked it with the fuel off a few times, and tried again.

nothing. A couple times it fired up then died before I could turn the gas on, then when I turned it on it wouldn't go again and I repeated the process.

I must have done that 30 times, my leg can't take it anymore and I don't know what to do.

I even put the original plug and coil back on trying to figure it out.

When I put the plug and coil back she fired up with the choke on!!

I let it sit for a couple min, and when I went to close the choke, she just died again. This happened twice.

There was also a small amount of white smoke coming out of the valve cover breather when I was trying to kick it over.

I know this is a long post but ever since i couldn't start it I've been searching the forums trying to figure it out i tried everything i could find.

now the bike ran fine before, except for that little hiccup.

So wtf is going on here?

any help would be appreciated!

Fuel, air, compression, ignition. It needs all these in the proper amount at the proper time to run.

Pull the carb, clean it, jets and all, check the float height and try again. Research is the key to understanding. Motorcycle carbs in general are very similar in form and function, so find a good tutorial on the way to clean it. Bet the carb is your issue. Don't forget to drain all the gas and start with fresh.

Make sure the oil is full and fresh so when you do get it running you don't toast the engine.

Best of luck. You will prevail:)

Edited by Jethrobolas

yeh im going with carb on this one. 99.9% of starting problems are carb related. a good clean out and reset would be the first thing i try but also look out for other obvious things like a unplugged wire or bad connections 

Edited by ekulb14

OK thanks! I'll give it a shot.

Even though it ran fine before I did the filter and plug you think that the carb could still be the issue?

I'd do it anyway. It may run fine after or it may not but at least you can rule it out.

It's really easy to do just do it on a nice clean table or bench so you have room to lay it all out on. Take pictures during disassembly to help when you put it back together. It's important to clean everything well but pay extra attention to the jets and little passages in the carb.

Good luck

Ok i will do tomorrow morning it's getting late now. I'll post the results here.

Thanks guys


When I put the plug and coil back she fired up with the choke on!!

I let it sit for a couple min, and when I went to close the choke, she just died again. This happened twice.




Clean out the entire pilot circuit (the jet and the port above the jet) then reset the a/f mixture screw when warmed up.

Edited by Navaho6

Since it does not run with the new parts installed, then they are now suspect. Do not use them yet.


Do the carb service and get it running with the "old" parts that allow it to run with the hiccup.


I'm assuming fresh gas is being used.


If it sat for awhile, beware of gummy ethanol leftovers that may remain in the tank.


Proceed very cautiously with any fuel tank cleaning. You can loosen materials in the tank that then flow into the freshly cleaned carb, ruining *that* job (carb would not longer be cleaned, but full of gunk from a poorly cleaned tank).


So, you ended with that it runs only fully choked, and if you remove the choke (choke is now off), it then dies.  That means it will only run while rich.  I think that means that, before cleaning the carb, it runs too lean.  I think...

My air fuel screw was out 2 3/4 turns. Shouldn't it be at about 2?

My air fuel screw was out 2 3/4 turns. Shouldn't it be at about 2?


You must clean and repair the carb first.


1.5 turns is your goal, but you just turn the screw for highest idle (starting with the lowest possible idle on the idle screw) and you are done.

Still no go guys. I took the carb right apart cleaned out everything

Jets all clean, measured the float it's dead on.

fresh gas in it.

made sure of the spark plug gap it's right in the middle of its tolerances. I checked for spark it's getting a good spark. It turns over fine. When using the elec start it turns over a couple times, sounds like it wants to go, but then doesn't. Choke doesn't make a difference, and after I try starting it I leaned it over and gas is coming out the overflow so it's getting the gas.

any other ideas?

Update I got it started, warmed it up a bit then closed the choke. She ran fine for 5 or so minutes idling then died again and doesn't want to fire back up.

I noticed it was running pretty hot, and my rad is very hot to the touch after only running a few minutes.

There's also 10 or so drops of oil that came out of the valve cover breather along with a little bit of white smoke.

All of that is normal


I would put in all fresh gas

Kind of weird... I got it running.. took the cam chain tensioner off and reset it and it runs fine.

Odd because I never took it off.

Only thing I noticed is its leaking lots of gas out the carb vent lines at idle and backfires a bit as I'm riding, (took it around the block) I just had it apart and measured the floats they were good and cleaned all the jets out.

why would it be leaking so much out of the vent lines?

Btw thanks a lot for everyone's help, I'm sure learning a lot about this bike!

Check the valve clearances. I chased the same sort if problem on my Pops bike only to find that one if the valves was out of spec. My guess is that you've got an intake valve that is too tight.

I'd say your needle and seat need cleaning, or preferably replacement. That would explain the fuel overflow, and hard starting. BT, DT.

I'd also check the petcock operation, splice in a fuel filter, stay away from ethanol gas.

I'm going to vote for a small piece a crap in the carb somewhere

Gunk makes this stuff that comes in a paint can called 'carb boil out'

soak it in there for a few hours and put the carb back in


The valve clearances are fairly easy to check too.....why not

Although its my belief that the clearances hold up for a looong time on these engines

Unless you beat the thing or run non syn oil


Just make sure to get a new valve cover gasket, the old one is probably all brittle and shixxy by now

Valves were good, cleaned out the carb again and the needle and she's good to go!

Runs well, starts easily.

thanks for all the help, saved a ton of money and learned a lot about the bike!!

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