Running Problem

I Just Took My 06 Wr450 Supermoto Out This Morning To Work And I Am Having Problems With Its Running Condition. It Idles At 1300-1400 Which Seems To Be Really Low. If I Sit At A Light For Any Period Of Time It Wants To Die. If I Give It A Quick Snap Of The Throttle It Dies. It Has Never Done This Before. I Have Tried Adjusting The Idle Screw But It Does Not Seem Like That Helped. I Have Not Tried Adjusting The Air Fuel Mixture Screw Yet. It Was About 40* This Morning And Never Reeally Rode It When It Was This Cold. Would That Matter? Any Help Will Greatly Help.


Has it been in storage recently? Maybe a through carburetor cleaning would be a good start. Check the accelerator pump operation while you are in there.

yeah I let it sit for about 5-6 weeks in my garage, i hate wisdom teeth problems. not to sound stupid but what would i be checking for at the accelerator pump?

Take carburator off then open throttle while watching from airfilters side into it. It should have a small streak of fuel spraying into middle of carburator.

when running?, its funny how i completely tore down my 01 yz350f and put it back together but I feel like I am clueless it sounds like when i work on this one

no not when running, put your bike on the stand and take the carburator off. Then just do what I wrote

Timo McKeown

I really appreciate the help guys, i am also thinking it might be a dirty jet or carb because I left the gas on for the 5-6 weeks I was unable to ride.

Actully you could remove (or just tilt up) your sub frame withyour carb still attached and twist the throttle and check the Accelerator pump squirt. If you want to get real tricky search "Oring mod and "Accelerator pump" in this and the YZ forum. There is lots of good tuning information and your bike will run better in the end.

The reason we suggest to check the Accelerator pump operation (squirt) is that you said when you open the throttle the engine dies. the accelerator pump is there to prevent this so you need to make sure it is working.

There are several post that do an nice job of explaining how the accelerator pump system works and how to tune it to its peak performance.

I think (you should verify) that the O-Ring mod is the best for your year bike. I belive that the new JD (James Dean) jet kits come with and o-ring for this accelerator pump mod in the kit. You may want the use James Dean jetting as another source of information.

Squirt timing and squirt volume are what you would be tunning.

hey thanks for the info

In order of what to do...

It could be jetting..... what the normal temp??? If its normally alot higher, you are running way lean. Try turning out the fuel mixture screw... This should fatten up the idle circuit. Next if that doesn't solve it, take the carb off the bike and disasemble the bowl, clean it, clean all the jets by blowing air through them, then if your picky check the float hieght. The pull the plug and pop a new one in. To be on the safe side I would also take the tank off, dispose of ALL gas in the tank, clean it with some new gas. Take the fuel line off and make sure its not clogged.

If all that doesnt solve the problem, you may want to check your valves.....


normally when i have been riding it it has been around 70-80*

That will make a difference. Follow my recomendations in order...

I'd try adjusting the fuel screw, its easy and can make a big difference.

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