Built ATC 200 head keeps lifting.

[zebvance]

Just had my 83' ATC 200 fully rebuilt. wiseco 10:1 compression piston, bored 2mm larger. RCM exhaust, Machined head, 30mm Carb, HP clutch pack and running on 104 octane. I now have had the head lift off the jug twice now, even after being torqued. I am riding this thing hard and its performing great besides this issue. I have done quite a few trials with about 80-90 miles on the build so far with a top speed of 60.1 mph. What are my options to fix? Drill and tap for larger head studs? A different stock size head stud that's maybe stronger and wont stretch? Some sort of loc tite on head studs?

Thanks

[ScreaminRed]

Maybe just your headbolts are worn or stretched. If you have access to a new set, try that. If you wanted to try an easy way you could use a washer then a lockwasher, then your head bolt and loctite it all. I think the red loctite is the stronger one. Or maybe use extra torque on the bolts since the motor is so much stronger now. Idk, just ideas.

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[6spdls1z28]

Just had my 83' ATC 200 fully rebuilt. wiseco 10:1 compression piston, bored 2mm larger. RCM exhaust, Machined head, 30mm Carb, HP clutch pack and running on 104 octane. I now have had the head lift off the jug twice now, even after being torqued. I am riding this thing hard and its performing great besides this issue. I have done quite a few trials with about 80-90 miles on the build so far with a top speed of 60.1 mph. What are my options to fix? Drill and tap for larger head studs? A different stock size head stud that's maybe stronger and wont stretch? Some sort of loc tite on head studs?

Thanks

My brother has a similar build to yours and it keeps leaking oil around it. It’s done this twice now we haven’t fixed it yet either so I’m hoping you figure yours out so I get an idea. Might have to try new studs like mentioned they’re the originals


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[Scootertrash]

Maybe just your headbolts are worn or stretched. If you have access to a new set, try that. If you wanted to try an easy way you could use a washer then a lockwasher, then your head bolt and loctite it all. I think the red loctite is the stronger one. Or maybe use extra torque on the bolts since the motor is so much stronger now. Idk, just ideas.

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I don't know if I'd go with red Loctite on head bolts. May cause issues down the road with disassembly. Just my .02

[shortline10]

Not a new problem , back in the day we used copper head gaskets , they seep a little but won’t blow out .
Look on eBay for them . They were made by big Al’s and Rocky . Might have to buy a complete gasket kit to get one but they are definitely worth it .

[zebvance]

Not a new problem , back in the day we used copper head gaskets , they seep a little but won’t blow out .
Look on eBay for them . They were made by big Al’s and Rocky . Might have to buy a complete gasket kit to get one but they are definitely worth it .

I this one was rebuilt with a copper head gasket

[oscarmayer]

Cooper gaskets leak. You would need to get a XR200 oem to keep it from leaking.

[ATC King]

What's the initial ignition timing set at and what's the max?

You may not be able to hear certain ignition events. A higher compression than stock may need less timing than stock.

Fortunately, the 185/200 engines have a manually adjustable ignition. Initial and full timing can be set with just tools and the curve can be altered with springs. The same as older automobiles. Little to no money is needed to adjust the timing.

All but the electric start versions have a dry flywheel, meaning you can put timing tape/marks on it and still see them, and not make a mess. With a tachometer and timing light, you can gather all the timing info you need.

Why does it mater? Abnormal and sudden cylinder pressure spikes...detonation, can blow head gaskets.