4 Stroke 07 250XCFW with 300 kit, submarine 2nd tear down

It ran fine for 80 mi on the trail, no noises, no loss of power, etc, and suddenly locked the rear wheel and died. Wont re-start. Turns over, shifts OK with motor off, rolls in neutral while getting towed to truck. Still full of coolant.

Drained oil and checked filter and both screens. Nothing. Magnetic drain plug even has less stuff than normal, but this is a quicker oil drain than normal too. Oil is good.

Took out plug, looks just right brown color and no metal beads of melted alum. Turn bike over with elec start and there is spark at the plug. Put hand on exhaust while turning and fell exhaust pulses. Also MAY feel it sucking back some-maybe not good.

Took off valve cover and turned motor. Chain looks good and is tight so dont think tensioner went bad. Cant see cam lobes too well. Tried to line up cam gear marks and they may be off. Got to check this further.

More later as it comes apart.
 
It ran fine for 80 mi on the trail, no noises, no loss of power, etc, and suddenly locked the rear wheel and died. Wont re-start. Turns over, shifts OK with motor off, rolls in neutral while getting towed to truck. Still full of coolant.

Drained oil and checked filter and both screens. Nothing. Magnetic drain plug even has less stuff than normal, but this is a quicker oil drain than normal too. Oil is good.

Took out plug, looks just right brown color and no metal beads of melted alum. Turn bike over with elec start and there is spark at the plug. Put hand on exhaust while turning and fell exhaust pulses. Also MAY feel it sucking back some-maybe not good.

Took off valve cover and turned motor. Chain looks good and is tight so dont think tensioner went bad. Cant see cam lobes too well. Tried to line up cam gear marks and they may be off. Got to check this further.

More later as it comes apart.
That bites Mike. HOpe it's not too bad. Keep us posted. :thumb:
 
Took valve cover off and looks good. Took cam bridge off and found LR cam had seized in the bridge, not the bearing side just the alum side. The cam has alum transferred to it, the cam bridge top n bottom halves are galled and ruff.

Now I just need to figure out why it happened. Mainly going to look for clogged oil passage.
 
Ok I am 4-stroke stupid, so explain a little slower what you have found. :smirk:
So does this mean the valves are not operating and you think this is because there is a a clogged oil passage which dried up the cam dohickies. So what kind of damage/replacement are you looking at once you figure out the cause?
Pics? :thinking:
 
I am ready now for another ride, as soon as I clean my filter that is.

I will need to order parts for the broken bike.

Brian, the cam rides in a bearing on one end and the other end is an oil bath in an aluminum carrier. The valves do work, but the cam has to rotate freely to push the cams open. So when it dried out and seized it locked up momentarily. The carrier is damaged and when I tried to re-assemble the cam in the carrier and turn it, it was so tight it wouldnt move by hand. It should spin spin in the carrier. Working on cause of loss of oil flow or whatever it was that caused it.
 
if the gaskets are correct or not blocking the oil passage,it sounds like the pump went bad.
I have heard of priming issues with these bikes,factory calls for filling the oil cavaties after oil service.
let me know if i can help. adam
 
I guess it could have been damaged on start up and then took that long to seize. I have received advice to take clutch side off take clutch off and turn the pump with a drill motor to see if it squirts. Also to check the bypass spring.
 
it only goes on one way

Ive studied this more now. If you put the cam in the bottom saddle it is firm to turn. If you put the top saddle on it and just press together it locks up solid. So this could definitely lock the motor up like it did. Explains the slow labored turning of the motor by the started after also. The oil galleys are clear so this appers to be the problem. A KTM enige builder said he had one do it too. He said since the motor was dry from me rinsing all the oil out it could take up to two minutes for the oil to get there to do its job.

So Im responsible by not lubing or getting the oil up there by cranking for extended period before firing the bike. Its under $300 for all the parts new and less if I can get the cam cleaned up.
 
got the cam used for $69 shipped and both bridges for $70 shipped, thats what Im talkin bout. Should be back together early next week when parts get here.
 
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