2009 WR450F Electric Start Issues

Hey guys. Thanks in advance for the advice.

I bought a 2009 WR450F a few months ago and can't seem to get the electric start to get the bike running. I have tried everything.

- New Battery

- Valves Checked - Adjusted

- New Plug

- Cleaned Air filter

Mods that were made prior to my owning it:

- Air box mods

- Engine Rebuild (not sure what all they replaced)

- FMF 4.1 power bomb header and muffler

Bike runs very good. Idles well and lots of power. Starter has no problem turning engine over it seems its just not quite fast enough to get the engine running. I have played around with it extensively and have got it to start with the electric start, but it fails 99% of the time. Kick start works best with choke and no throttle when cold. Hot start pulled when hot.

I just put 150 miles on it last weekend and it seems to be rock solid. A little popping during decel but no flat spots or any reason to think its too lean. I really want to get the electric start working so looking for ideas as to what to try next. Im 5'10 and its hard on the hip to get on top of the kicker!

Thanks again,


Probably they put YZ cam in it. They don't like to E star with the YZ cam.

Thanks Bandit... That would make sense. The owner played the Hare Scramble game and obviously was dialing it in for racing/performance.

It also has the well documented issue where the engine "misses" while running at mid RPM. Its really noticeable on the road. I assume this is the TPS issue. But when I run the RPM's up it is very smooth and great power. Would the YZ cam be something that would make that ignition problem worse?

If they did use YZ parts in the rebuild, is this something that would be wise to replace with original WR parts to make the bike more reliable? I am using it for trail - enduro style epic rides and really need it to be reliable more than faster than stock.

Thanks again. I appreciate the advice


It should be just as reliable, just won't start good with the button. TPS Stutter is something I never notice, can't help there.

Maybe this will help. This was taken from the pinned sticky that says, WR FAQ at the top of the WR450 Forum page. Clark4131 put it together for us.

Q: Why does my WR seem to miss when I hold the throttle steady in the 1/4 to 1/2 turn range?

A: That's your TPS (Throttle Position Sensor) doing it's job. Dirt bikes don't normally run with a steady throttle off road and they weren't designed too. Unplug it and see if the "miss" goes away. If so, then you know. You can also follow the procedure for checking the TPS voltage in the manual. It's extremely simple if you have a multimeter and some folks have found that it is set funky from the factory. Once properly adjusted, the problem goes away.

Edited by Bandit9

Interesting, my wr250f has stage one hotcams in it which are similar to the yz cams and its starts perfect with the E-start. My jetting is up to par with all my mods, and i have a Shorai lithium ion battery. The stock lead acid batteries would always give me a problem when trying to start. The shorai starts it up every time, even in gear

It seems that my electric start issues are battery related. I put a new battery in and it started off e-start first try. I think I may need to upgrade my stator next. I did the baja designs kit to make it street legal, including converting the stator to DC only and it doesn't appear to be charging enough to get battery voltage back to full.

Anyone have suggestions for full DC stators that output more power than the stock stator with DC mods???

Thanks again in advance!

I got my stator from RickyStator, Mike helped me on the phone. He was a big help. TrailTech or Baja Designs can help you as well. I run mine DC, since I did that, I haven't even needed to charge my Yuasa battery. Been about 3 years of reliable service.

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