looking for box muffler for 48cc Grubee, lawnmower style

happycheapskate

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If this thread is in the wrong place, sorry. I am new, and i think it should fit here. Please be friendly. I love bicycles and i'm glad to join the MB club.

I have a 48cc Grubee Skyhawk, on a beach cruiser. I am looking to find a muffler that will bolt onto the stock motor, which is just like a big weedeater or lawnmower pancake or box muffler. I don't want pipes and stuff hanging off. I may have to make one out of a junction box and some fiberglass. I don't know. I'm looking for something that will just bolt on or that can be welded onto the cutoff stock exhaust pipe, to help other noobs and people with odd bike frames that the stock muffler doesn't fit without hitting the frame downtube.

I may just cut it off, or bend it with a torch, but I doubt it will last too long then.

IF you are on the same quest, please join the thread and share.

If you find a supply of bolt on box mufflers, you'll be my hero.

The only downside of this style muffler will be it will eventually clog up (carb spray and a drain hole might help) and it may get your leg dirty from soot blowing. I think it would not be a problem though, and want to try it.
I can always just put a regular muffler on later.

Thanks
happycheapskate.
 
I couldn't make your link work but I think I know what your talking about so I tried to put on a stock HS box muffler on and it will fit if you get longer studs and drill out the mounting holes on the muffler just slightly and mount it upside down looks kinda cool and would love to hear how it sounds/Works kinda like a mini exp.chamber. I have pix if you would like to see what I'm talking about!:geek:
 
It has come up recently about using the cigar shaped Briggs muffs -, they really work good (especially using 2 in line) however, the guys say they clog up in a 2 stroke.
 
i tried using a pancake style lawnmower muffler on the end of my expansion chamber. The results were good as far as noise control and backpressure (increased bottom end torque).
BUT, this muffler will collect a lot of oil over time and i think it will clog up after awhile. I used mine for about a week, and i didn't like the way it looked (nice chrome pipe with a plain steel lawnmower muffler just didn't look good to me).
so i modified the stock muffler to go on the end of the expansion chamber.
i gutted the stock muffler, drilled a few holes in the baffle plate, and cut the end at a 45 degree angle.
works like a charm and looks good too.
 
Please share more details. This sounds like a lead. But I don't know what an HS is. I cannot picture the part you describe. Longer studs are available fairly easily for the Grubee Skyhawk. Just source some allthread type rods or long screws as long as they are threaded all the way down.

Be 100% sure its the same size and thread or you'll ruin your motor! (or cost more to fix than its worth).

I couldn't make your link work but I think I know what your talking about so I tried to put on a stock HS box muffler on and it will fit if you get longer studs and drill out the mounting holes on the muffler just slightly and mount it upside down looks kinda cool and would love to hear how it sounds/Works kinda like a mini exp.chamber. I have pix if you would like to see what I'm talking about!:geek:
 
Why don't you share a favorite link to a product or home made how-to page, please? I don't know what an X Box is but I suspect you don't mean the video game console.
 
re: x box

wkqpti.jpg


This is about the right concept, maybe more advanced than I was thinking. The ports don't match, and the grubee fins won't let you mate a flat surface to the engine.

But this is about the right idea. Perhaps you could cut a gasket facing out of a peice of steel and weld it to a cut off Grubee pipe, then mount the muffler safely away from shoes and legs and frame.

I'm going with bending my stock pipe out just enough to fit, but I'm interested in other solutions because the heat will probably wreck the paint.

I mounted the front of the engine one a plate and riser washers, bolted through the frame, so I get more room than normal.

2kppbo.jpg


I also plan to get a metal junction box, cut a hole and screw holes in the flat plate to mate with the carb, tack a couple little wires or something over the hole, then use a cut down Briggs lawn tractor foam as a filter. The box will have nickel sized knock outs and screw onto the plate. Screw these cheesy little filters.

If you are building a rat bike and have a welder, you could try this with an old stock muffler for the mounting face and a few inches of the tube:

Weld a heavy steel food can to the pipe, with the big open end away from motor. make baffle plates out of about 10 or 12 lids, littlle lock washers, and 2 long screws. Paint it black with barbeque grill paint. I bet it would sound tough and you could adjust it by the plates and the spacing of the closest plate to engine for backpressure.
 
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