taking exhaust outside the box

#1
I would like my new motor to be muffled a good deal. Even if it loses some power.

This is the top of a stock GX200 muffler and I wonder about the circle shaped structure there.
Would that be a good place for a second outlet? Has anyone drilled a stock muffler full
of holes and it still sound OK? I have a clone muffler I will experiment on, it's 1/2 the size
of the Honda. I do think there is a right and wrong place to drill, from something I read
years ago. I guess too some aftermarket pit bike,dirt or Grom mufflers could work. Something like the
Cherry Bomb straight thru glasspacks I had on my '60 Impala 348. But I would like to alter the stock muffler
if possible.
Comments? Questions? Snide remarks?


IMG_20190106_155838909.jpg IMG_20190106_155838909.jpg
 

65ShelbyClone

Well-Known Member
#5
I just googled "GX200 muffler cut open." Figured someone had probably done it. ;)

That said, using the factory muffler/spark arrester from a 175-250cc 4-stroke enduro or trail bike (NOT a motocrosser) would probably cut sound the most and performance the least. Unfortunately they are often rather large.
 

electrathon

Active Member
#6
I would like my new motor to be muffled a good deal. Even if it loses some power.

This is the top of a stock GX200 muffler and I wonder about the circle shaped structure there.
Would that be a good place for a second outlet? Has anyone drilled a stock muffler full
of holes and it still sound OK
? I have a clone muffler I will experiment on, it's 1/2 the size
of the Honda. I do think there is a right and wrong place to drill, from something I read
years ago. I guess too some aftermarket pit bike,dirt or Grom mufflers could work. Something like the
Cherry Bomb straight thru glasspacks I had on my '60 Impala 348. But I would like to alter the stock muffler
if possible.
Comments? Questions? Snide remarks?
Are you trying to get more power/noise or make it quieter? The more you open up a muffler, the louder it will get. the more baffling and directional changes the exhaust needs to travel the quieter it will be. The write up is good, but it is done to make more airflow, it made the exhaust louder in the end. If you want quiet you either need to create a third chamber inside the muffler (there are two, make a third) of add a secondary muffler after the factory muffler.
 
#7
Are you trying to get more power/noise or make it quieter? The more you open up a muffler, the louder it will get. the more baffling and directional changes the exhaust needs to travel the quieter it will be. The write up is good, but it is done to make more airflow, it made the exhaust louder in the end. If you want quiet you either need to create a third chamber inside the muffler (there are two, make a third) of add a secondary muffler after the factory muffler.
I couldn't even get the lip pealed back! Now I see a header with 2-3 flippers in it.
 
#9
Howdy FirePower, me and Rex RTT talked over a one-off
looper with a RTT flipper. I wanted a 2nd flipper but he told me
there wasn't room for two, but that he'd look for a way to run 2.
 
#12
Howdy FirePower, me and Rex RTT talked over a one-off looper with a RTT flipper. I wanted a 2nd flipper but he told me there wasn't room for two, but that he'd look for a way to run 2.
I'm using one on a hot rod Tecumseh. It does attenuate the noise, but no where near a muffler would. There is a slight performance difference, but not enough that I can tune it out with the Mikuni jets or metering needle.

https://www.oldminibikes.com/forum/...powered-full-suspension-cat-250.162413/page-5
 
#13
Oh man, Dave, that Cat is over the top. You builders put so damn much into
your work!
I can imagine how proud you are of that bike, it's a jewel.
 
#14
The circle shape is a plug at the end of the tube that goes up into the muffler from the exhaust flange. The AGK article shows how they ground the weld down and removed the plug to open up the muffler case and add punched holes to the baffle plates. The packed pit bike mufflers are a nice idea, but they rap like CherryBombs on full throttle. They're only quiet at idle and light throttle. You could try one with a db killer in the end of it for a nice compromise in sound and flow.
 

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