exhaust pipe wont stay on

long story short i tried everything to get the bolts to stay on, but they keep vibrating off from the head. I even tried JB metal weld and that didnt work. I eneded up stripping the inside of one of the screw holes and the other has too much JB weld in it to go back in properly, what do i do? will I have to tap them?
 
hey guys, I took the bike to a welder and he said if he did a welding job it wouldnt last because the engine is made of aluminum, and the exhaust pipe a different metal. is this true? anyhow, i managed to tap the holes with new threads, secured them with red locktite, and then put JB weld all around the mating surfaces. its holding for now. However, the bottle part of the exhaust pipe broke off its weld job and now it just hangs, can I leave it like this?
 

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Do you have a rear hanger on the exhaust? Without one you will continue to have problems, make sure the engine is mounted solid to reduce vibration.
 
Some machine shops will do the Heilcoil job for a fee. I'm not sure at what is the point at which you just get a new jug (cylinder) for less. I had about 40 years ago spent $20 to have them do a Helicoil on a spark plug thread hole in the head for a MC where it was like 4X otherwise for the cost of a new head for the MC. Buying the whole kit is an investment, though I found a distributor local back in San Jose that sold individual special size drill bit matching the tap and the Helicoil and bought just a few. not a whole kit. The guy even told me how I could avoid buying the insert tool and use what I had lying around to suffice. In any case, note that the Helicoil is multitudes stronger than the pot metal the head is made of will be much better than any of the thread inserts you also may have heard of. As was already said extra support is really necessary aft of the connection to the port so undue strain is not to damage it all over again.
 
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