Exhaust threads stripped !

sonic883

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hi, I have a 80cc 2 stroke engine that i have have ridden for a few months now. In general almost everything is going well, just yesterday noticed my exhaust was quite loose. I went to tighten the bolts and it just wouldn't tighten. The bolts i use are allen key bolts that has worked really well for the past few months. I flashed a light to the thread holes to see they are completely stripped. I cut some a bolt in half and used them as studs,i hammered it into the holes. for a moment i thought i had fixed it, when tension came when tightening the nut as it should, it twisted the bolt with it... I have posted this because im quite stuck on what to do, helicoils ? any ideas on for a quick fix.

i am considering riding with no exhaust... :ROFLMAO:
 
A new cylinder would be the easiest fix, instead of augering out the holes and tapping to next larger size or heli.
 
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If it was me I'd just drill out for a 5/16 bolt and then tap. I have all the stuff and bolts to do it though. If you have no tools, just get a new jug. Save ya some money. Tap set is 40 bucks, bolt is 5 cents, drill bit 2 bucks. New jug is 35 bucks an ya don't have to go to menards, it will show up at your door. Lol.
 
used a tap and die set. tapped the holes and and inserted the studs,then screwed the nuts on. The exhaust seems to be holding up fine, need to reinforce the rear of the muffler.
 
Make sure you have the bottom of your muffler tied to the engine mount or bike frame as the vibration can make the muffler a big pendulum that will damage the flange threads in the cylinder. I don't over torque the exhaust head studs, they are subject to the hottest part of the engine and will recieve in excess of 500 degrees in cyclic heating and cooling.

Most motorcycles/engines have their exhaust manifold and muffler supported back along the frame in at least 2 or more supports so the pipe isn't relying on the cylinder or head flange to keep the pipe from flopping around at speed.
 
I know this thread is 9 months old but I want to add this as an update for people who maybe going through these posts.

I went to harbor freight and bought a tube of alumalloy brazing rods (8 rods for $20) and filled the bolt holes and drilled and tapped them all.

The alumalloy is a little tougher than what the engine is made out of so make sure that you have the motors head securely fastened to something and get out your high carbon bits and take your time doing it. You will find that they will no longer strip out. Better than brand new.
 
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