yz450f Kick starter hard to kick after water pump change?

Hey guys,


Apologizes if I am posting in this wrong forum but having some issues with my 07' yz450. My bike was running fine after (dun dun duuun) I decided to upgrade my water pump to a Boyesen water pump.in addition to rebuilding my water pump.


I took off the right clutch side crank case cover and replaced the two water pump seals and the impeller bearing. After that was done I re installed the impeller shaft following the service manual and put the new water cover and the crank case cover back on with a new gasket. I put new coolant and oil into the bike and it kicked over just fine. I ran it for about 30 seconds before I realized the new crank cover gasket was not fitted correctly so some oil was leaking out from the seam of the case and the cover. Irritated I decided to wait a few days to fix it.


Re drained the fluids and finally got the gasket in place and attempted to kick over the bike but now the kick starter will jam. Feels like it is hydro locked and feels like it is in gear. It will sometimes let me kick it fully but then on subsequent kicks it will jam. If I give it gradual pressure it will engage but a "normal kick" will jam it.  I did a quick push start and it almost fired up but was nervous about trying to do it again if something was screwed up in the engine. 


I thought I had installed the impeller shaft or jammed the water pump gear but after taking it off it spins fine. I also took off the crank cover again removing the impeller shaft and the kick starter is still jammed.The water pump gear looks fine. Also tried adjusting the clutch, and inspecting the kick starter spring but still nothing.


From looking on here it appears it could be a ton of things but wondering if anyone had any ideas?

It may help to troubleshoot to remove the spark plug and, with the cover off, rotate the assembly in place by the crank nut to see what goes on.  If it's something in the gear train, you can isolate it easier that way.  Be careful trying to operate the kick starter without the cover in place, but check to see it works right as far as the ratchet camming in and out of engagement, etc. 

OK so I thought I had fixed the issue but it reared its ugly head after running my bike for about 5 minutes. I took out the spark plug and removed the valve cover and noticed that the cam gear alignment was way off. I put the bike at top dead center and re-aligned the gears. That resolved the locking kick starter issue. I put everything back together and the bike started up and I let it idle for a few minutes. I started it up again tried to ride it but after about 50 feet and then it just suddenly died. Tried to re-start it but the kick starter was starting to lock again. So something is definitely causing my timing to go out of sync.  


So here is what I am think are the issues:


1) Worn out cam chain

2) Broken cam chain tensioner

3) Bad install of bearing or seals for impeller shaft   


I just am suspicious that the new impeller shaft bearing I installed is either bad or i installed it incorrectly however; I did a quick spin test and the impeller is not spinning as freely as the stocker but I thought that was just part of new bearings? In addition I noticed that with my cam tensioner does not let me adjust it. When I turn the screw it will compress but once I release the screw it pops back to the full extended position? Is that normal?

The additional drag is due to the new seals you installed (presumably) on the WP shaft.

If you find your cam timing out again, you will probably find that your cam chain has several very stiff, binding links in it. That will cause the chain to jump time. Replace the chain and tensioner. Hopefully, you haven't bent a valve.

Thanks Grayracer for the help.


I have ordered a new cam chain, cam tensioner, fly wheel puller and some new gaskets. I will hopefully have some time this week to install them and give an update later this week. 

So I ended up ordering a new cam chain and tensioner and it appears to have fixed the issue! Having examined and my old chain and new chain it was definitely obvious that my old chain was ridiculously stretched out. This is definitely not the funnest of activities but is doable in a few hours. It was either that or wait month and a half and pay $500+ on labor and god knows how much on OEM parts at my local crooked bike shop. 


The hardest part was getting the cam timing correct because of how taunt the new chain was. I was forced to remove both cam covers and move the cams so I could align the timing.  

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