I had a mini bike in the seventies that had a piece of chrome 2 inch pipe behind the muffler. There was a piece of expanded metal rolled into about a 1 inch tube, wrapped with fiberglass that I could install or remove. There was a sheet metal screw on the bottom to hold it in place. It sounded like a hot rod with the baffle removed. It was really quiet with new fiberglass installed. Hardware cloth would be easier to bend. The chrome tailpipe was under the seat, about 18 inches long. you can buy a chrome extension like that from most part stores.
DIY Mini Bike Glass Pack Style Muffler/exhaust
- Thread starter nightgrider
- Start date
That is correct. The rear muff has a removeable "glass pack" that will not hurt performance or jetting. I do not think the extension was even clamped to the muffler. It was mounted under the seat but it was not tight to the muffler. I remember the fiberglass got black, greasy and yucky so it needed to be changed occasionally. It had a cool blub blub sound without the baffle in it and whenever I put the newly wrapped baffle in it, it was spooky quiet. I think this is what some of you are looking for.
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Awesome! Similar to stories I've heard of people back in the 70's running multiple mufflers on there street machines to make them more of a sleeper. No one expects a quiet car to be built. Also falls in line with exhaust theory where you only need to tune to your first exhaust restriction. What comes after that doesn't seem to matter much. Wish I had more time. I'd build up some different designs to test.
Correct! One sheet metal screw in a hole in the bottom of the chrome pipe, long enough to hold the baffle in.
I thought you would like this idea, based on a few comments you made about neighborhood riding.
Actually, the chrome pipe slid over the hot dog muffler but was not clamped. I suppose it could be welded or otherwise attached.
I thought you would like this idea, based on a few comments you made about neighborhood riding.
Actually, the chrome pipe slid over the hot dog muffler but was not clamped. I suppose it could be welded or otherwise attached.
Mr. PInk, I am sure it could be applied, but you said "back pressure". Any change in exhaust pressure on a small 4 stroker might require jetting changes. A quick and easy exhaust mod that requires a tedious and exacting fuel system adjustment is no longer quick and easy.
I do like your suggestion. Might contact you about some cooperation. Dave
I do like your suggestion. Might contact you about some cooperation. Dave
These are great ideas for aftermarket solutions though! So yes, cool stuff, as usual, from both DaddyJohn and Mr. Pink. Back pressure and performance (and I'm hearing jetting) are so intertwined that maybe you could go too far (ie: restrictively) with the baffles? Or at least a point where you have so little permeability that flow performance really begins to be impacted, and jets can no longer save you (or your sanity, at the very least)? And here it seems glass threads could be more forgiving in terms of pressure... I admit that I'm totally green here, but also wondering if I might keep jetting and performance the same but quiet the ride by just pointing the exhaust at a fiberglass-stuffed enclosure? (An overgeneralization I kno..)
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