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Heads and Cylinders All about your porting, compression, rings, cylinder and piston modifications to your bicycles engine

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Old 09-11-2016, 11:38 AM
Slogger Slogger is offline
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Default Re: Headbolts

I tighten them to a half a tug past snug. <about 15 foot pounds>
I don't even have a head gasket, never did.

I never mess with them til the engine is cool. The aluminum threads will strip easier when hot.
Buzz zzzzz zzz
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Old 09-11-2016, 11:45 AM
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ezrider ezrider is offline
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Default Re: Headbolts

I'll just have to specify a 'deep socket' which should work. Supposedly, the head bolts are already factory tightened, and you don't have to fool with them. However, its never a bad idea to check those head bolts along with all the other fasteners just to play it safe.
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Old 09-11-2016, 09:35 PM
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sbest sbest is offline
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Default Re: Headbolts

Originally Posted by buba View Post
Cylinder stud -case metal sucks what is a non helicoil fix when a head gets lose and compression firing causes a stud to strip in case???--Anyone??? success stories???
Compression firing never strips the threads on these engines. It is always human error. If it was running well while you had it, it wasn't likely the previous owner. The case metal on these is not so bad either, but some of the owners....

If you have a 48cc motor with M6 studs, you can always drill and tap them out to M8. Room for the nuts will be a bit tight but 12mm x M8 nuts are available. If you have the 66cc with the M8 studs I don't think you are going to get M10 in there. Not a lot of metal around the stud for an insert nut. Pretty much gotta use a helicoil.

As for what tool to use, the M6 nuts are pretty much always 10mm and due to the depth you have to use a socket. The M8 studs have 12, 13 and 14 nuts available. 13mm is ISO standard, 12mm is Japan standard and my Grubee came with 14mm, go figure. I carry a short "tube wrench" for on the road repairs:

Stripped threads on these motors are pretty much always operator error. You have to use a torque wrench at least for the first 5 years of your motor mechanic existence. I use one in all the critical areas still.

That's a mighty noisy bike you got there, it must haul a lot of ass?
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Old 09-11-2016, 09:59 PM
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mogollonmonster mogollonmonster is offline
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Default Re: Headbolts

Compression stripping at less than 180psi... Nope. Operator error. It might be aluminum but it ain't a pie tin. Blame the dog, but not compression.
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