HELP! 2004 yz450

I recently bought a 2004 yz450f. I've owned and maintained 2 strokes in the past, but this is my first 4 stroke. The bike ran excellent when i bought it but the more and more I rode it, the harder it got to start. checked the valves, and sure enough they were all out of spec. Well I tore it all down, put new shims in, and reassembled the bike. All the valve clearances are now within spec. Anyways, the problem that I have now is that my kick start lever is locked up. The crank will still turn from the nut on the crank, but I cannot turn the engine from the kick start. I rechecked the timing multiple times and it is all set up the way it should be.

My next move to try to figure this out was to see if the kick start itself was the issue. I removed the cluch basket to get a look at the gears. all the gears looked alright and with the clutch basket removed the kickstart moved freely again. As soon as i re-installed it, it was locked.

I feel that I am probably overlooking something simple, but I would just like to get some suggestions or solutions.

Thanks in advance,


The earliest YZ450's, including early '04's, had some trouble with the kick starters, and the assembly was upgraded mid year '04. But you may have an assembly problem. The basket engages 3 separate gears, and it can be challenging to get them all meshed properly. There is the main primary drive gear on the outside, and the gear on the back needs to engage both the kick idler and the oil pump idler gears. The way you know for certain is that the thrust washer that goes between the basket and the boss (clutch hub) will slide onto the main shaft far enough to drop off the inboard end of the main shaft splines. If it won't, the basket's not all the way on something.

Thanks for the reply. The thing that is confusing me is that i never had a problem with it until I did the valve adjustment. I mean, i havent even started the bike since the valve adjustment because of this. Is there something that i could have done wrong in the valve adjustment process that would cause me to not be able to kick the bike? Like I said before, the engine itself isn't locked up because i can turn it over revolution after revolution with a wrench on the crank bolt.. timing is good and nothing fell into the engine. The kickstart will still move freely when the clutch basket is out too so i think it might have something to do with one of those small gears you speak of.

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