Stripped Thread/Bolts

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kar_the_terrible
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Stripped Thread/Bolts

#1 Unread post by kar_the_terrible »

I have two stripped thread and bolt problems on my bike:

1) An allen bolt on the clutch cover is completely stripped/rounded and the hex key just spins. Also, this is pretty badly seized and in a bad location, so I can a good grip on it with vise grips. Is the best solution to drill it out and retap? I'd rather be ready, than have my clutch cable break and no way to get the cover off without jerry-rigging a suicide shift ;)

2) I think my right cylinder spark plug is starting to cross thread. And I think Im losing some compression as a result of this. While this is not to seriously affecting power or performance, one time in the rain I noticed bubbles near said spark plug. Whats the best solution for this? Tapping? thread adapters? I do have access to a machine shop, But I would prefer not having to take the head off or anything (which I assume you would need to retap the spark plug thread. Is there something like liquid gasket that I can use...
'78 Yamaha XS400
'86 Yamaha Radian

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TechTMW
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#2 Unread post by TechTMW »

FOr your clutch cover bolt, maybe you can notch the head and try a screwdriver? I would drill it out as a last resort if you still have something to play with there.

The best way for the spark plug is to take the head off and retap. Sorry dude, but there's no other way (in my opinion) to safely retap the threads.

You could just run a tap thru there, or drill it and use a helicoil, but there's no way to prevent swarf from getting into your engine unless the head's off.
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9000white
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#3 Unread post by 9000white »

you can pour water around ANY spark plug and it will blow bubbles--dont worry about it.
dr bob

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#4 Unread post by maximnewb »

I've had very similar problems working on my truck.

Although some (including myself) would definitely say it's risky, there's one thing you could try for the spark plug....

take the appropriate tap and coat it with a grease (especially the valleys where filings are designed to fall away) and use this to correct the threads.

Since you're only re-tapping there shouldn't be too many shavings and hopefully most/all of them should be caught up in the grease. Then just clean out the hole.

Like I said, a bit risky....but if you're not satisfied you could always take the head off anyways.

As for the clutch cover, notching it with a hacksaw and using a flathead can work (depending on the angle and space you have to work with) like techBMW mentioned.

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#5 Unread post by maximnewb »

Oh yeah....somthing you could also try for the clutch cover.

Use JB weld to glue an allen key into the stripped out bolt. Scratch up the head of the bolt first to give it some texture for the JB to stick to. Give it a full 24h to dry before trying it and use some excess JB weld to make sure it's as strong as possible.

Once that stuff dries it's almost as hard as metal! Quite the incredible product.

I've seen this method work when the space it too tight for anything else.

Hope this helps.

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#6 Unread post by kar_the_terrible »

Solved.!!!

FYI I hammered in a slightly oversized hex key into the bolt... (used SAE/ASE instead of metric) and used a giant-"O Ring" 1/2 inch driver about 1.5 feet long and used brute force to take the bastrd out. Of course needless to say that totally destroyed the bolt so i had to get a new one.

Yaarrhh!!!
'78 Yamaha XS400
'86 Yamaha Radian

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