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first xr 200 rebuild

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I posted earlier about my XR 200 not starting after a fall. I now have the whole engine dismantled and am waiting for a manual. This is all foreign to me and would like anyone that knows to take a look at some of my images and see if anything jumps out at you.

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Valves have obvious carbon build up. One chain guide had a chip in it. Cylinder wall has the tinyest scuffs.

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From what I can see this bike still should have ran, although not very well, it still should have ran and am not so sure you tore down the motor prematurely. 

 

I see minor issues on the piston, would have liked to have seen the piston skirt too, cylinder walls (abrasive markings) [took debris from the intake side ?], camshaft (bluing indicates overheating).

 

I think you have jumped the gun and torn down your motor, with very little data to go on. 

 

I would have checked the compression at least before going through the formality of a tear down. 

 

Even if you rebuilt the motor, I am not so sure it could be motor related, it could be electrical, or fuel delivery issues as to why it stopped running.  

 

Michael 

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What would make the valves hit the piston?

How do I prevent them hitting next time?

Piston cleaned up well with steel wool. Any issues here? Other than having to vacuum out flakes of steel?

Skirts look really clean.

White deposit on springs??

How does that sprocket look?

Would a broken chain guide impede running?

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Cam chain can jump when out of adjustment and loose, this puts the valves out of time with the crank and then piston can hit valves. The valves should be seated an sealed with the head off and rocker box off. Your picture shows both valves held off the seats. At a minimum you need new valves and should have the seats reground. I would also recommend a new piston. Cam chain and sprockets along with the guides should be considered as well.

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My piston has the tinyest knick in the top? Will it run with the old one?

Cause more damage?

How do you re ground them?

Emery cloth ?

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The seats would need to be done at a machine shop.

Ok, I think sometimes we get carried away with doing things the RIGHT way. If cash is tight and you just really want to get up and running again I supose you can cut corners. The valves MUST be replaced, everything else is a judgement call. Try and at least get a new top end gasket set as well. There are lots of YouTube videos that walk through pretty much every step you need to do.

Good luck I hope you get it running soon.

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The seats would need to be done at a machine shop.

Ok, I think sometimes we get carried away with doing things the RIGHT way. If cash is tight and you just really want to get up and running again I supose you can cut corners. The valves MUST be replaced, everything else is a judgement call. Try and at least get a new top end gasket set as well. There are lots of YouTube videos that walk through pretty much every step you need to do.

Good luck I hope you get it running soon.

agreed the valves must be redone. It looked like your timing gears are pretty worn down also. They should be replaced.

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How do I know if the chain is okay?

I'll get new valves and see how it looks...

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From the picture of the cam sprocket you can tell it's thrashed. If it was my bike I would replace the chain, sprockets, and guides. The chain and sprockets should be replaced together. The costs start to add up quickly. If you can afford it replace all that stuff, if not replace the valves and hope for the best. I put a xr100 motor back together that looked worse than yours and it still runs ok. Fingers crossed, knock on wood.

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Your cam sprocket is EXTREMELY worn out. The cam chain skipped over a few cam teeth when you fell and threw your valve timing off, thus causing the valves to go down at the wrong time and make contact with the piston. I had a xr200 and the same thing happened to me after i fell one day

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Replacing the cam sprocket, cam chain, and valves is a must. The piston should be replaced but it will problibly run fine with a couple little dents on the top

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