Need some help mounting exhaust!

[adboio]

[cross-posted from r/motorizedbicycles]

Hello! Recently bought an 80cc build on Craigslist to use for my commute to class every day. It needed a ton of work, and I'm almost done, except it's loud as s**t and I want it a bit quieter. The kid I bought it from did not have the stock exhaust anymore, so I ordered this exhaust from Amazon (will be here tomorrow): https://www.amazon.com/gp/product/B07MNK316W/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1

However, I just went to check it out and it looks like one of the mounting holes by the exhaust has some sort of stud stuck in it, or a broken/absolutely-demolished-and-no-longer-resembles-a-bolt bolt with no head. I can't get it out for anything. It also looks like the hole this "stud" is in is smaller than the other one?

This is my first time ever working with a motorized bike, and was just curious if anyone had ideas on how to mount this thing. I was thinking about using the one hole I have to mount it, maybe finding some way to glue it on the other side, and then attaching it to the frame at another point. However, I have no clue what size that hole is and even less of a clue as to what kind of glue I'd use for something like this. Any suggestions are appreciated!

Also, any suggestions on things to watch out for with this being a used bike would be appreciated! Trying not to die on the way to class, that's my professors' jobs

 

[extremeodd]

Due to the temperatures and vibrations involved there are no epoxys that would hold. If you took it to any machine shop they could probably extract the broken stud for only a few dollars.

The other hole may indeed be larger due to the previous owner possibly breaking off both studs, then only Drilling and tapping one hole to get by. If you want to do this as cheaply as possible without buying any tools, you might be able to get away with using one bolt and then a long-ass worm clamp wrapped around the cylinder holding down the other side. This is not a good solution, and I can't imagine it would last very long before you snapped the single stud that's holding the pipe on.

Your best bet would be to pull the jug off the motor and simply take it to any machine shop and have them fix that problem for a few dollars. Removing that jug requires only removing the 4 nuts on the very top. Or you could simply replace the jug for less than $20 and with maybe 15 mins of "work".
https://www.ebay.com/itm/MOTORIZED-BICYCLE-47MM-66-cc-80cc-40-MM-INTAKE-STUDS-CYLINDER-BEST-QUALITY/273786746982

 

[adboio]

Due to the temperatures and vibrations involved there are no epoxys that would hold. If you took it to any machine shop they could probably extract the broken stud for only a few dollars.

The other hole may indeed be larger due to the previous owner possibly breaking off both studs, then only Drilling and tapping one hole to get by. If you want to do this as cheaply as possible without buying any tools, you might be able to get away with using one bolt and then a long-ass worm clamp wrapped around the cylinder holding down the other side. This is not a good solution, and I can't imagine it would last very long before you snapped the single stud that's holding the pipe on.

Your best bet would be to pull the jug off the motor and simply take it to any machine shop and have them fix that problem for a few dollars. Removing that jug requires only removing the 4 nuts on the very top. Or you could simply replace the jug for less than $20 and with maybe 15 mins of "work".
https://www.ebay.com/itm/MOTORIZED-BICYCLE-47MM-66-cc-80cc-40-MM-INTAKE-STUDS-CYLINDER-BEST-QUALITY/273786746982

Thank you for the advice! I've been messing with it for hours and can't get anything to work. Willing to just buy the new jug... what are the measurements they list? The one you linked was '47mm ... 40mm intake studs' and another I found was '47mm ... 32mm intake studs'. Where could I take those measurements? For reference, if it makes a difference, the exhaust I ordered had '44mm' in the title, and it fit perfectly. Is that the 'intake stud' mesaurement? Then is 47mm just a standard 'engine size' or something?

 

[FurryOnTheInside]

I would just replace the cylinder.
You've been running with no exhaust, presumably "the kid" did the same. There's a strong chance that the cylinder lining is damaged already.
Even if it wasn't, the one stud hole probably had the threads ripped out and would have to be tapped to M8 the next larger size, the same may have to be done to the one that currently has the broken stud stuck in it. Then that means the holes in the exhaust flange need to be drilled to 8mm too, so you can get the thicker M8 studs through, and thicker studs need bigger nuts 13mm, so then there's probably a clearance issue as the studs are so close to the exhaust pipe so you can't get the nuts on.
It can go on and on like this, one problem to solve (replace cylinder) or one after another after another.

Maybe 13mm nuts will go on, but I haven't tried. It could be a cheaper option if it works. But we don't know the condition of your cylinder lining yet. You will need to check that!

 

[extremeodd]

Thank you for the advice! I've been messing with it for hours and can't get anything to work. Willing to just buy the new jug... what are the measurements they list? The one you linked was '47mm ... 40mm intake studs' and another I found was '47mm ... 32mm intake studs'. Where could I take those measurements? For reference, if it makes a difference, the exhaust I ordered had '44mm' in the title, and it fit perfectly. Is that the 'intake stud' mesaurement? Then is 47mm just a standard 'engine size' or something?

The 32mm vs 40mm is the intake stud spacing otherwise all other measurements will be basically the same from jug to jug. 47mm is indicating the piston diameter, all of these 66cc/80cc 2 strokes run a 47mm piston and approx a 40mm stroke.

The main differences are if its a 32mm intake or a 40mm intake which simply is how wide the intake bolts are and has no bearing on anything other than that, or if it is a "high pin" or "low pin" piston which has no influence on jug selection (for the most part, this can be a can of worms) but is simply to accommodate if you have a long or a short connecting rod.

The beauty of these motors is how flexible they are with parts, as long as it bolts up you can use it for the most part.

If you don't have an easy way to measure the stud distance, there is an app called "Ruler" on the play store that turns your screen into a pretty solid little ruler. Otherwise, a dime is just under 18mm wide, if the intake bolts are spaced wider than 2 dimes wide its a 40mm, if it's less or almost equal to the dimes, its a 32mm.
Or you could just buy a jug with a 40mm intake and buy a 40mm intake manifold and not worry about it.

 

[adboio]

Thank you everyone for your help/suggestions! Ordered a new cylinder and it just got here, waiting on a new mounting kit to get here as well so I can replace the cylinder and the mounting hardware all at the same time (the threads on half the bolts are stripped and the engine starting coming loose after about a mile of riding). The new problem is that the exhaust hits the bike frame, so I've got some cutting to do, but that shouldn't be too difficult. Will be sure to update this thread once I've got it all figured out!