03 wr450 died???


13 replies to this topic
  • xyzracer

Posted February 03, 2005 - 08:07 PM

#1

Well, went out riding today (almost), and after warming up my bike I rode about 200 yards and everything was going fine until I hit the first turn and gave it some gas. The bike then started sputtering and died. It felt like i fouled a plug (from my 2 stroke days), but when i tried to start it up again, no compression. Please help, Thanks.

  • ddialogue

Posted February 03, 2005 - 08:16 PM

#2

Have you checked for a sheared woodruff key? The first thing I'd check is to pull the cap on the left case cover and see if the flywheel nut has backed off.

Good luck!!

  • wildo

Posted February 03, 2005 - 08:21 PM

#3

That woudn't cause a compreshion ishue. My guess is you broke a pstion ring or your motor jumped time and bent one or more of it's valves. Their is no comp. at all right?

  • NMRIDEN

Posted February 04, 2005 - 06:29 AM

#4

That happened to me this past year on my 00' WR400. Lost all compression. I also thought that it was a fouled plug by the way it was acting. I tryed everything. Turned out to be a stretched/borken cam chain, and a broken cam chain guide. When this happens the bike loses all timing and therefore has no compression. Turned out to be relatively cheap to fix, and cured the problem. I think it was about 250.00 parts and labor. Good Luck :cry:

  • Frostbite

Posted February 04, 2005 - 06:44 AM

#5

The only other thing I can think of is you sucked in a broken piece of throttle slide plate and it's stuck under a valve. The older WR's were breaking them but I'm not sure about the newer ones.

  • PBDBLUE

Posted February 04, 2005 - 06:46 AM

#6

Actually a sheared woodruff key could cause you to loose compression since the crank/cam timing relationship will be disturbed. Remember the exhaust cam has an auto decompression that holds the valve open during a portion of the stroke. Check the key first.

  • Dan_Lorenze

Posted February 04, 2005 - 08:08 AM

#7

I'm gonna guess that it's the key that got sheared. I've never fouled a plug in one of these bikes, it's possible but I think the key sheared. Do yourself a favor and check the flywheel nut, if you can loosen it with the bike in gear, that to me means that the flywheel isn't seated properly and could mean that it's the key. The is all too common for me to think it's anything else. Please keep us up to date...

Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • Lowedog

Posted February 04, 2005 - 08:58 AM

#8

I have seen spark plugs vibrate loose and actually totally unscrew. This would cause the symptons you describe also.

Let us know what you find out.

Lowedog

  • xyzracer

Posted February 04, 2005 - 10:27 AM

#9

thanks guys for all the info, just wanted to know where to start. I had the flywheel lapped and loctited when i got the bike, but i know that is still a major issue with the 03s. I also heard somewhere that sometimes the auto decomp gets gummed up somehow and causes it to stick open, but i am still going to check the woodruff key first. Thanks again.

  • Frostbite

Posted February 04, 2005 - 10:58 AM

#10

Actually a sheared woodruff key could cause you to loose compression since the crank/cam timing relationship will be disturbed. Remember the exhaust cam has an auto decompression that holds the valve open during a portion of the stroke. Check the key first.


I hope I don't sound sarcastic but I'm curious. How would the loose flywheel affect the cam timing? On my 400 the cam drive sprocket is on the crank, inside the cases and has nothing to do with the flywheel. Are the 450's set up differently? Even if the ignition timing were thrown off, the bike would still have compression, like when you kick it over with the kill button on.

  • jbrooks26

Posted February 04, 2005 - 11:44 AM

#11

This was my first thougth to. Has happened to me on more than one occasion, usually on a borrowed bike. Although it has happened on one of my bikes too. I agree also with Frostbite, I would think if the key was sheared it would still have compression, just not fire in the right place. Just my 2c, hope this helps.

Josh

I have seen spark plugs vibrate loose and actually totally unscrew. This would cause the symptons you describe also.

Let us know what you find out.

Lowedog



  • RichBaker

Posted February 04, 2005 - 02:18 PM

#12

Actually a sheared woodruff key could cause you to loose compression since the crank/cam timing relationship will be disturbed. Remember the exhaust cam has an auto decompression that holds the valve open during a portion of the stroke. Check the key first.

Nope....woodruff key locates the ignition rotor on the crank. It won't affect compression one iota. It does affect ignition timing.....

  • PBDBLUE

Posted February 04, 2005 - 04:42 PM

#13

Actually you guys are right. I forgot that the crank gear is not attached to the flywheel on the WR so the cam timing should not be affected. However the decomp mechanism is engaged so there shouldn't be much compression when kicking it over normally.

  • yamaha227

Posted February 05, 2005 - 01:52 PM

#14

My 03 WR 450 died about a month ago, after going through everything with a multi meter, trying another carby on my bike and just about everything else i could think of i decided to pull the head off to check the internals out.

Found my piston to have a crack from one side to the other straight across the top, had cracked all the way through to the piston pin.

Luckily no other damage, so now where to find a nice after market forged piston?

Could be a similar problem with yours if you've checked everything else...




 
x

Join Our Community!

Even if you don't want to post, registered members get access to tools that make finding & following the good stuff easier.

If you enjoyed reading about "" here in the ThumperTalk archive, you'll LOVE our community. Come join ThumperTalk today!

The views and opinions expressed on this page are strictly those of the author, and have not been reviewed or approved by ThumperTalk.