Just got my bike and was changing the muffler. It would not line up due to the studs on the back of it. So, I figured I'd better loosen the pipe at the cylinder so as not to stress that joint. One bolt came out easy the other was hard the whole way. Sure enough the threads on the end of the bolt were filled with aluminum. Previous person that messed with it did not use Never-seize. Anyway, I cleaned up the bolt with a die and chased the threads in the cylinder with a tap. Some threads near the surface are gone. The ones at the bottom appear good and I'm sure there are some "half height" threads in between. Bolt will now thread in by hand the entire way. I certainly don't want to over torque being that the threads have been compromised but i don't want it coming loose either. Might use a longer bolt with a washer. Won't have the "acorn" head but might catch a few more threads.  

Looking around on this website and some on Google, I keep coming up with 16.5 ft./lbs. Doesn't seem like a lot but, if I ruin what threads I have left, I'm all done.

https://www.bing.com/images/search?q=double+ended+stud&qpvt=double+ended+stud...

Before you make a mess.

You could tap to the next size up maybe.
If it's SAE, who cares? Then stick a nut on it.

According to FSM, 13 - 20 ftlbs
with your threads being damaged, I'd go with the lower and check more often.
recommended is 4000 miles or every oil change.

Thanks, guys. I did in fact use a bottoming tap with the idea of possibly creating an additional thread or two. Of course working in aluminum, it's easy cutting. The only bolt readily available was 5mm longer so I stuck a washer on it. In fact I changed both bolts to keep things looking the same. I thought about retapping to the next size up but, working down on the floor and up behind the forks would mean using a hand drill. Certainly didn't want to break the engine down to put it on the drill press. That's a good suggestion to simply stay at the low end of the torque range and check frequently. My torque wrench is a 1/2" drive wobble handle so I will go out tonight to see if I can find a smaller one of the "clicking" style. Everything is just snugged up and looking good. After I get the torque wrench to final check things, I'm ready to fire it up.

I always put anti siege on ex fasteners. And the joint between the head pipe and the muffler. Sawed apart enough rusted on mufflers and drilled out enough broken exhaust flange bolts for this lifetime....

You might try wrapping some of the outer threads of the bolt in the thinnest cheapest Teflon tape you can find ,if it works it may prevent any wobble from vibration and may give the threads in the bottom of the hole a chance to hold better.I like Dave's idea also.

Armen wrote on 07/29/17 at 11:46:58:


This is my suggestion as well.  Even though I don't have any problems, I will do this to my bike (whenever) as I think a stainless stud threaded ALL the way in & a good stainless nut is preferable to original setup.  That way, when you want to remove pipe, you only have to remove the nut and if stud ever gets stripped, just replace it.

USE Copper or Stainless NeverSeize.  Do not use the aluminum NeverSeize.