Stripped drain plug

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t7275tr

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After draining the crankcase of the wet sump oil this morning ,when putting the bolt in, I realized that the threads in the case are compromised. When you put the drain plug in, when the bolt bottoms, you can turn the bolt with very little torque being placed on the bolt. There is no aluminum on the the threads of the bolt. Is there a repair that can be done without breaking the engine down ? Drilling and tapping the hole would likely get metal into the crankcase. Your thoughts?
 
t7275tr said:
After draining the crankcase of the wet sump oil this morning ,when putting the bolt in, I realized that the threads in the case are compromised. When you put the drain plug in, when the bolt bottoms, you can turn the bolt with very little torque being placed on the bolt. There is no aluminum on the the threads of the bolt. Is there a repair that can be done without breaking the engine down ? Drilling and tapping the hole would likely get metal into the crankcase. Your thoughts?
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It can be done... carefully. I've had to do it myself.

You will need to get a Recoil kit for the thread size (From here on my couch I *believe* it's 3/8 UNC). You should lie the bike on its side to make this job a lot easier. Fill the flutes of your drill bit with the stickiest grease you can find, and go slow. You can remove the bit every so often to clean it out. Once the hole is drilled, the rest is easy. Just don't lose the stainless Recoil tang up in your crankcase. That'll cause a lot more trouble than an errant aluminum shaving.
 
Hi,
The drain plug on my 1974 850 is 3/8 course thread. If I ever strip mine, before I install a "Helicoil" I will try to more simply put in the next size bigger bolt/thread (whether it be metric, SAE, or other). Sometimes the difference is so small that you will not even need to drill, just tap it right out, good luck.

GB
 
geo46er said:
Hi,
The drain plug on my 1974 850 is 3/8 course thread. If I ever strip mine, before I install a "Helicoil" I will try to more simply put in the next size bigger bolt/thread (whether it be metric, SAE, or other). Sometimes the difference is so small that you will not even need to drill, just tap it right out, good luck.

GB[/quo te]
Yes, 3/8 UNC is the thread. I corrected my post. Thanks..
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last winter I did just that ,strip the thread I mean . I tapped M12 in the cases and in the M12 bolt tapped M6 .So each time I have to drain the cases I undo the M6 , thus avoiding stripping the coarse M12 in the alloy cases .
It takes a bit longer to drain but as both bolts are stainless at least i am at rest knowing that there is no danger in fouling the threads
btw I once LOST a drain plug and got home by squeezing a bottlecork in ...that bodge served me a whole summer
 
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