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2000 yz426f kickstart stuck, won't move??

By moeschger2000,
in YZ400F/426F/450F/450FX

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moeschger2000

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Looking for some ideas on what might be wrong...

Started my bike up fine, let it warm up for a little bit then took it for a spin up the street to make sure it was all running good for my ride the next day. All seemed ok until I was coming back. Pulling up my driveway I pulled the clutch in and started coasting, when all of a sudden the bike stopped, and seemed to lock up.

Now the kickstart can't be kicked at all, it won't even move, kind of like kicking a solid wall. I have done the following.

1. Took the clutch plates out and drive train moves fine back and forth.

2. Took the header off, I can see two valves still there on the exhaust side.

3. Took the valve cover off and everything looks ok, i.e. nothing broken.

4. Removed the spark plug and I can feel air coming out while turning the motor. So piston seems to be going up and down.

It seems like I can only rotate the motor to a certain point and it stops. I can then rotate it backwards until a certain spot. When it does stop the cam lobes on the exhaust side are up, and the intake are down.

Decompression lever is working.

Not sure what is going on, intake valve, is there a gear in the kickstart drive train that could be gone??

Any ideas appreciated.

Thanks.

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VB_Racing

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Since he is feeling air coming out of the cylinder when he turns the motor, I am putting my money on the big end rod bearing. If I remember correctly that was a pretty common problem on the 426. Time to pull her down unfortunately.

Dave

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FEAROFRUNNER

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I just had a similar problem with my 00 426 and i think it is probably a one in million chance what happened but maybe it somehow happened to you. I've got the white brothers full exhaust with the tunable disks in the end. There are six allen head bolts that hold the disks and the end all together. The heat from the exhaust (I’m guessing) melted about a quarter inch off two of the bolts. One of the ends found it's way through the baffling and honey comb frame that holds the baffling, down the exhaust through the header through the valves and onto the top of my piston. Now i know this probably sounds like a bunch of BS but I’ve got the bike apart and pictures to prove it.

Anyways to answer your post, you might want to take the head off and inspect the combustion chamber. Luckily for the inside of my motor this little incident happened when I laid the bike over and it wasn't running. But just like your situation here, bike was running fine, hit the ground, picked it up and tried to kick it over and it was locked up. Pulled the head and found a smashed tip of a bolt and some indents on the piston and head only place it could have hit without serious damage. I'd love to post pics if anyone wants to see them. Sorry for the hijacked thread but I needed to share this crazy $h*t with someone ?

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VB_Racing

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Didn't he say he pulled the clutch in and was coasting? If true, then it shouldn't matter if the engine is frozen or not. Doesn't it have to be something in the tranny?

No, it's the opposite. If you pull the clutch in and the bike rolls, then the trans and clutch are free. He cannot get a full revolution out of the crankshaft,and cannot kick the motor thru, that is bad.

Dave

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FEAROFRUNNER

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I'm thinking I'm going to pull the top end off and see what I find. I'm kind of thinking and hoping just for a bent intake valve hitting the piston.. Hopefully I have time this weekned.

Thanks for all the input..

When was the last time you changed the timing chain? Since your going that far into it (which really isn't that big of deal if you haven't done it before) might as well order up a new timing chain to throw in while your at it. Good luck and don't be intimidated, yamaha made it simple to tear these bikes down. ?

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  • 9 years later...
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Denospamoney

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On 3/12/2009 at 5:27 PM, FEAROFRUNNER said:

I just had a similar problem with my 00 426 and i think it is probably a one in million chance what happened but maybe it somehow happened to you. I've got the white brothers full exhaust with the tunable disks in the end. There are six allen head bolts that hold the disks and the end all together. The heat from the exhaust (I’m guessing) melted about a quarter inch off two of the bolts. One of the ends found it's way through the baffling and honey comb frame that holds the baffling, down the exhaust through the header through the valves and onto the top of my piston. Now i know this probably sounds like a bunch of BS but I’ve got the bike apart and pictures to prove it.

Anyways to answer your post, you might want to take the head off and inspect the combustion chamber. Luckily for the inside of my motor this little incident happened when I laid the bike over and it wasn't running. But just like your situation here, bike was running fine, hit the ground, picked it up and tried to kick it over and it was locked up. Pulled the head and found a smashed tip of a bolt and some indents on the piston and head only place it could have hit without serious damage. I'd love to post pics if anyone wants to see them. Sorry for the hijacked thread but I needed to share this crazy $h*t with someone :)

dude i think you just answered my question... I'm gonna bet you're not alone 

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