2009 YZ450F Locked up



I bought a 2009 YZ450F, but the bike has not been used for the last 2 years... I changed the oil, and put in fresh gas before attempting to start it for the first time. I kicked it about 20 times before it started. I noticed some smoke by the engine, but I read that is common when it is really cold outside. The engine shut off after a few seconds. I tried to kick start it again, but the kick starter locked up completely. I also notice that it wont move when it's in gear while pulling the clutch.


I have never worked on a four stroke before, so I decided that this might be a good time to learn. I did get the service manual, and have been doing a lot of reading and watching Youtube videos to get myself more familiar with this engine. I thought it might be sticky clutch plates, and maybe the timining chain that jumped. I started to open the engine, the timing chain looked fine, however the intake cam was facing the exact opposite way that it's supposed to be. I removed the cylinder and the piston and rings seems to be fine, but when I lift the piston up the crank only turns a little bit before it get stuck.


Does this mean I need to replace the crankShaft or can it be something else that is causing the crank to get stuck? Also, what would you guys recommend to replace since I have the engine open?


I will probably open the rest of the engine this coming weekend.

Put it all back together and time it correctly sounds like the chain must have jumped had the same problem with my bike

Excuse my ignorance, but since the top end has been removed ,and the timing chain is not restricted by the cams, isn't the crankshaft suppose to turn freely?

Sorry I was the ignorant one didn't read that part of the thread what happens when you kick the kick starter with the head off (or just push it)? The crank should spin freely then it's kind of hard to cycle the motion of the crank while guiding it with the piston

I was second quessing myself now, so I went to check out the timing chain. I pulling on it, and the crank was turning without any problems. When I started all of this, someone told me to open the crank cover screw, and see if I can turn the crank the way the engine will spin, but not to force it if it wouldn't turn. It was completely stuck and wouldn't turn.


So the chain jumped, and cause the crank to stuck and now that it's back on track it seem to be good? If that is the case then I don't regret opening and learning more about this engine. Also happy that it's not costing me money.


Hopefully adjusting the TDC will be have the bike running smooth again, besides from the clutch, which I think might be sticking due to sitting for 2 years.


Thanks for your input.

No problem just make sure you but a new timing chain!

That was my next question, I assume this chain is stretched that is why it jumped. I will order a new one now.



And make sure the timing chain tensioner is working correctly.

And make sure the timing chain tensioner is working correctly.


Thanks.I will test the tensioner today to make sure it's good.

It has been recommended in a diffrrent thread to replace chain every 12 to 18 months. Im not sure about reusing the head or base gasket either.

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