It Just Wont Fire!

I was out riding on some dune today all going sweet got about 30ks up the beach went i pulled up and switched the bike off. Then when i went to start it nothing happened kicked for about ten minutes just popped a couple of times. Checked for spark which it had but seemed a bit weak. My motor has only been rebuilt recently is it true that woodruff key can shear due to wrong torque on flywheel. has any one heard of an australian bike shearing a key?

All 03 WR450's world wide can shear the key. Get the 04 Starter upgrade parts. Most likely you sheared the key with a slight backfire during starting. Search for 04 starter upgrade posts on this forum. :cry:

Thanks indy will search for 04 upgrade. Do you think thats whats happened or could it be timing chain jumped a couple of teeth.

Try replacing the plug. I had a plug foul once that still gave a weak spark but it ended up not being enough to run the bike. :cry:

Definitely try the easy stuff first. I went riding last weekend and it took me almost an hour to start my '02 WRF. I was so tired, I had to have my buddy on his 2-smoke kick it over for me. It finally started but it ran kind of crappy. I've never had this problem before with any other of my kickstart big bore 4-strokes.

Needless to say, the next day I picked up two new NGK CR8E plugs, changed the old one out & it fired on the 2nd kick. I'm keeping the spare one in my tool bag so I can do a swap out on the ride in case this happens again!

chain skipping a couple of teeth would probably mean valve meeting the piston, so dont even imagine it if the piston movement seems undisturbed

yeah i had a spare plug with me tried that. just how it was backfiring when i was trying to start is making me think of timing or woodruff key. I love the wr but in three rides ive had to push it more than ive been riding it if this keeps up think i will be seeing something orange sitting in my shed :cry:

sounds like a plug foul. If the timing chain jumped a few teeth there'd b no valves left and you wouldnt be able to kick it over. When the engine pops when you are trying to start it, it indicates it's been flooded. The 'pop' you hear is unburnt fuel (generally in the header pipe) exploding. If a 4XX doesnt start on the first dozen kicks it's generally flooded and needs to be 'vented'

With my 426, I hold the throttle wide open with the hotstart on and kick it over about 10 times. This clears any unburnt fuel from the chamber and header pipe. She always goes 1st kick after this. Alternateively push start it. It'll start heaps easier with a push than it will by kicking it. My procedure is to push the bike in nuetral, pull in the decomp, click it up into second then release the decomp after the engine have done a few revolutions. This allows the crank to gain some inertia, and greatly reduces the chances of locking the back wheel, even on sandy/loose terrain.

sounds like a plug foul.


just my experience, but if i kick my bike ten times with no fire, (and no obvious critical items overlooked), I go right for the plug.

Especially true since the awesome 450 cam mod.

quickly pulled valve cover off today turn motor over to TDC cam are in right spot but flywheel mark is about 45 degrees out so i guess the woodruff key has claimed it latest victim. will pull side cover and flywheel off tomorrow but am 99% sure its the key. bugger

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