Drilling holes in muffler By couchman420 (Read 19,851 times)

[couchman420]

I have herd of people drilling holes in their stock muffler to get a wee bit more power and deeper/louder tone from their scoots. Most of what I have seen is drilling 2-4 holes next to the original exhaust outlet on the muffler, ~1/4 in. dia.. My question is, what if you drilled more, smaller holes, such as 10x 5/16 in.? Would that make any difference compared to fewer, bigger holes? Would that make my scoot sound like a poorly-tuned honda civic with a fart-can exhaust?

I apologize in advance if this has been asked before, I am just trying to make sure I don't do something that is stupid AND irreversible.

[jct842]

if you dont like it pop rivets or sheet metal screws to close them up. one thing if you open up the exhaust with out doing anything to the air in you are not going to see any improvement or very little. I have a briggs and straton muffler on my 150 and did a new aircleaner along with bigger jets, I gained a little but it is not night and day difference. If you need a whole lot more performance you have the wrong scooter. putting up with the extra noise was probably not worth it in my case. same type noise you get with your lawn mower!!! john

[Bashan]

No need to apologize for questions, the biggest scooter snobs have asked them all at one time or another. John is right, the guys that have did this said they MAY have got some HP boost. You are definately going to have to tweak the air and gas once you start messing with the exhaust. I think one of the problems is nobody has figured out exactly where to drill the holes. I haven't quite been able to sacrifice a muffler yet and hack saw it in half to see where the best spots would be. I do like the idea of a farting scooter tough, a real attention getter. Rich

[couchman420]

Thanks for the replys guys. I'm not looking for a major performance boost, or even a minor one. TBH, it's just my eagerness to mod my scoot.

I'd assume the area directly around the little exhaust tip would be a good location.

[Alleyoop]

What your trying to do is allow the exhaust to exit out faster and not be restricted by the small outlet. But then again the mufflers have baffles inside to direct the exhaust around and in and out to quite them down. So yes holes around where it exits will allow more exhaust to flow out quicker but it will be a little louder.
Alleyoop

[ce]

Just drill a little hole under the outlet, run it, see how you like it, drill a bigger hole, try it again, then drill a bigger hole, but don't go out and buy a big ol' Mongo drill bit just so you can keep drilling.

You can feel the reduced back pressure and the engine will breathe a little easier, it's not really louder if you didn't get the Mongo bit, and at WOT you'll get a nice response, so drill, baby, drill.

Then get a 26 mm carburetor on ebay for like $35 and put a 110 main jet and leave the stock pilot jet, don't worry about the airbox, it'll be fine with the new carb, but you could drill it out a little bit, too, someplace where no water or dirt can get into the filter.

Then send me $30, and I'll send you a coolscoop fan shroud for the ne plus ultra mod that'll make your scooter the coolest thing on your street.

[couchman420]

OK. Thanks for all the info. Someday soon, when I can pry myself away from my computer (my main passion in life), I'll start drilling. I just have two more questions.

First; would drilling more, smaller holes, such as 2x 1/16 in. sound any different than one larger 1/8 hole? What I'm looking for here is a different tone, not just louder.

Second; I'm assuming after I drill a hole, I'm goin to have to paint it in some way to prevent rust. Will regular spray paint work, or should I use high-temp paint like they use for engine blocks?

[Bashan]

Acoustics is a weird field, I'm sure different size holes would set up different pressure waves and therefore sound different. But I don't think anyone could predict how your scooter will sound. Like John says, it's reversible. I like the idea of a Mambo drill bit though, it sounds fun. You'll definately want high temp paint. Rustoleum makes some inexpensive and indestructible products for this type of painting. I used them extensively on my Frankenscoot and found they're actually easier to use than conventional paint. They make a paint just for headers and mufflers, that's what I used. I got it at Lowes but I'm sure you could get it at Walmart. Rich

[ce]

Papa likes Mambo
Mama likes Mambo
Baby likes Mambo

But it ain't gonna change yer tone to a deep throaty roar. For that you need P&P Shark Tip, with a 40 millimeter tube.

I put one on my MC-18 B, and it sounds way cool, but it was expensive, and kinda flopped around til I secured it better.

I drilled my sons stock muffler with a 1/4 " bit right under the spigot, and it sounds better, but it's not borderline obnoxious like mine.

So if you want something to really be a main passion in your life, start making all those mods you're dreaming of.

Go ahead, I dare ya.

[jayblaze]

Yes this is all good info, I have a Motobravo Hornet 150cc GY6 motorcycle.....and this thread makes me wanna DRILL!! lol....sounds inexpensive if you just want to modify it for sound, because I was thinking the same thing, how can i make a scooter engine sound like a motorcycle, pretty hard....would definately have to spend some money like the Shark tip...

[couchman420]

Success! OK, I ended up drilling 2x 15/64 in. holes above and below the exhaust outlet. The results are more of a put-put-put sound from the engine instead of a purrrrrr, which I like. And for future reference, if you drill the top-half of the muffler, you will let more exhaust gasses out than if you drill the bottom half (at least that's how it is with my stock muffler). Pics and maybe an exhaust note video coming in a little while; I need to try and sleep a little bit.

[couchman420]

Ignore the messy garage.

[jayblaze]

Oh very cool, so do you get more of a motorcycle noise now, or what do u mean PUT PUT lol, sorry, just trying to figure out the before and after noise, but Im wondering if i can do that to my hornet, only difference is its chrome metal piping. Cant wait to see your video!

[13lky2]

Your Hornet has a much larger exhaust exit than the pea-shooter in the pic. I wouldn't worry about drilling it, if you want more noise, run a straight pipe or get a Super-Trapp and use less disks.

[89newbie]

And when it needs its inspection renewed what do you do with the holes??