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Broken Muffler Studs... JB Weld?



JB Weld Muffler?

Greets all...

I recently sheared off the cheap Chinese bolts holding my muffler to my Hua Sheng frame-mounted 4 stroke motor. The funny part is I just bought tempered steel bolts made here in the US to replace the old Chinese ones. As I attempted to remove the old bolts, they sheared right off. I didn't even apply much pressure. I tried to use vice grips to remove the protruding part of the now headless bolts and it sheared off flush with the engine. These are really small bolts and I don't believe they make an easy-out that size. I also tried to grind a slot in the top and remove them with a flat screwdriver without any luck. I tried briefly to drill them out to retap the holes but I had no luck making any progress on them. Is there a special drill bit I need to do so? Is there an easier way? Now I have a really loud motor that has lost about 5-8 MPH from its top speed. Can I JB Weld the muffler back on? I hear great things about that stuff. Also, I don't plan on ever removing the muffler. I figure I will replace the engine before I ever need to remove the muffler for any reason. Any thoughts? Would I be doing something that could hurt anything? Please advise... Thanks in advance. :)

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It may be a blow to your pride, it would be for me, but I would take it to a small engine shop and let them do it. I highly doubt JB Weld would last long.

Irish John

I agree with the above Vyzhion. Don't try this yourself - a good metal workshop will do a good job and you can get to know them when you're there cos it's always worth making friends with these places. They help me with lots of things and give me any off-cuts I want for free. You can't afford to stuff up with removing this stud and when you take the motor off you can avail yourself of the chance to try changing the tray bolts that screw into the aluminium to ones with lock nuts on the ends so the whole tray holds together firmer and the bolts can't come loose or strip threads in aluminium.


Active Member
Jun 15, 2008
Yes indeed - the day may have come - when it's time to find a good shop.. Many years ago I worked in a small engine repair shop - there's not much we can't do - WHEN WE HAVE THE RIGHT TOOLS.. Retired now and due to the Calif. Cedar Fire back in 2008 - most of my tools are gone.. I now have made friends with a gentleman who owns a large shop -- just down there yesterday -- a job that would be a pain in the butt done here at home -- 5 min at the shop.. PS - I use JB weld very often - many times in cases where others think I am nuts --- but - to reattach muffler -- don't think so... Happy Riding from - Mountainman


May 31, 2008
I had the same problem with one of my bolts. I drilled a hole through to the opposite side and fed a piece of wire through and twisted it. It holds fine with the one bolt and the wire. I also used high temp silicone for a gasket. It's a good temporary fix. I think the best thing wouild be drill out the bolt, fill the hole with aluminum, tap new holes and install proper studs.

best wishes,

Irish John

If I remember right it's a thinner bolt than a 6mm. I've had numerous 6mm studs shear off flush with the engine casing on those wretched HTs. The metal shop guys nearly always got the bolt out by drilling into the head and putting an oxy torch on a bit of metal that they stuck into the hole. This helped them to break the loctite seal. They usually always got the bolt out in one piece. Those bolts on the exhaust are 4mm I think which is too thin for the purposes. They'll know how critical it is but I can't really see on my own engine if there would be room to tap a larger thread size in. You'd probably be OK with 5mm dia. bolts but they are hard to get. I think 6mm would take you too close to the engine casing. I don't think the bolt would have sheared if it hadn't been so thin to begin with. Not the engine designers fault cos these motors weren't built for bikes and only needed to hold the little silencer box that they came with. I think this bolt snapping could happen to any of us and probably will especially given the full length exhaust pipe I use which, apart from those 2 thin bolts, is only supported at the far end. Good luck. I'm fairly confident the bolt shaft can be removed with heat and drilling etc.