Post by oldchopperguy on Jun 1, 2013 2:55:23 GMT -5
While I was modding my cooling-fan scoop, since my factory exhaust system was rotting away, I also made up a SIMPLE, free-flowing exhaust header.
This mod is mostly about the header, but it could be used with most ANY type of muffler-system you have handy.
The expansion/contraction chamber system I used is one I had on hand from before I even had a scooter. I am almost certain it was for a 50cc GY6, and I simply cut off the front end and adapted it to my header.
I made the header after finding the exhaust-port in the head on my Xingyue 150 is a FULL ONE-INCH inside diameter. The factory exhaust header was a SCANT 3/4-INCH inside diameter. THIS pretty much renders any better muffler system to no avail!
You CAN find 1" I.D. headers, but they're a little pricey, and you really have to search. They are also rigid, requiring perfect alignment of the entire system to prevent torqueing of the header/head joint.
I fashioned the header flange from a used John Deere or Onan generator header, with it's upper "stub" cut off, and the bend pie-cut and tightened.
Here are some pix...
Here's what the Johnny-Popper headers look like "as found"... LOL... I got these off eBay for $5+ $8 shipping. They are a full 1" I.D. and the flange is a perfect fit to the exhaust-port in my GY6 150 head. They ARE near BULLET-PROOF STEEL.
Here's the header with the upper "stub" which went into the block of the Deere flathead cut off and ground smooth. Also shown is the "pie-cut" I made to the inside of the bend, and then squeezed up to match the super-tight bend of the 3/4" factory pipe and had welded up. (This IS necessary to keep the header routed between the engine and frame, factory-style.) I was going to run the pipe in a gentle bend UNDER the frame, but that's NO GOOD. It puts the pipe too low, and it would hit any obstruction, damaging the engine. You have to keep it in the tight, factory position.
Here's the finished pipe, compared to the factory pipe. The main pipe is made from aluminized-steel flex-exhaust made for generators, implements, etc. It allows JUST enough flex to let you feed it through the frame, and align it with ANY system you like! The heat-wrap-tape is a MUST. It replaces the outer tubing on the factory pipe, which keeps the pipe from roasting the engine oil. I wish it COULD be routed UNDER the frame, BUT... you can't have the exhaust header the lowest part of the scoot, or you'll break off the cylinder first time you kiss a speed-bump.
Here are all the parts laid out for installation. You can see the unwrapped pipe here. The flex-tubing is a perfect "slip-fit" over the Deere header, and fused/sealed to it with "INFERNO"; a 2,400-degree header-repair material from Auto-Zone.
Here is the "finished" exhaust... Once you have a flexible 1-inch pipe exiting at approximately the factory position, you can easily "hook it up" to any muffler you can dream up, simply using auto-exhaust adaptors, reducers, clamps, or whatever you can envision. This old 50cc setup seems perfect for my 150. It's quiet as a mouse, and runs like a bear!
This is the "muffler" I adapted. (You could use a Briggs & Stratton, "Cherry-Bomb" glass-pack, shorty Harley muff... ANYTHING you like!) You're only limited by your imagination. I cut off the front header portion that bolted to the 50cc head, so it could hook up to the flex-pipe. For a mount, I used a single piece of 3/8" x 1-1/4" aluminum bar-stock, drilled to bolt to the factory muffler-clamp bolts. I fashioned muffler-clamps from the originals, using a BIG vice, and a BIG crescent wrench. Not too difficult, and GREAT exercise...
I anchored the cut-down clamp-rubber insulators to the tapered chamber with black Hi-temp RTV silicone. It blends right in. This particular system is feather-light, and "straight-through" with not one baffle anywhere. Nasty appearing, BUT very, VERY quiet.
My muffler-clamp bolts were STRIPPED from the factory, so I got new ones from LOWE'S. I tapered the ends, and cut grooves with a Dremel Tool and cutoff wheel to make the ends into "thread-chasers". It cleaned up the welded-on nuts, and worked like a charm! A good trick to remember on these scooters...
This thread is mainly a quickie "how-to" for making a full-diameter performance header that's flexible enough to make it EASY to attach to any muffler you may have. However, this little expansion/contraction chamber has proved to be perfect on my individual scoot. I already had the Mikuni carb main-jetted a tad rich, and the engine LOVES this system!
Hot in appearance, and totally straight-through with not a baffle anywhere, not even it the little glass-pack "stinger" muffler, it's a fooler! At idle, it's QUIETER than a stock muffler! (aparently the big chamber dissipates the velocity of the exhaust gas, so very little noise goes through the tiny red stinger-muff.) Under hard acceleration, it barks some, but nothing objectionable.
The UNI-sock filter actually makes more noise than the exhaust! Now THAT'S a quiet bike that won't irritate anyone. And, since it's many pounds lighter than the stock muff, it greatly reduces un-sprung weight! THAT is VERY good for handling. Now the rear wheel "scampers" across railroad tracks, instead of "staggering" over them... YUP!
The best thing about the sound of this is that it lost that "Asian" "blatt... blatt... blatt... sound, and now resembles the sound of an old Brit single thumper. Or a Briggs & Stratton lawn-mower... EEWWW... I prefer the "thumper" analogy... Anyway, it now sounds ALMOST like a proper engine, instead of a kitchen appliance... LOL!
After some brief test-rides, I'm FULLY convinced that any "improved" exhaust should begin with a full, 1-inch inside-diameter header. The small-diameter factory headers truly "strangle" the engine BEFORE the exhaust ever gets to any muffler. I can REALLY feel a difference in mine.
I truly hope this thread encourages some of you to help your engines breathe better!
Ride safe!
Leo (still wrenchin') in Texas
This mod is mostly about the header, but it could be used with most ANY type of muffler-system you have handy.
The expansion/contraction chamber system I used is one I had on hand from before I even had a scooter. I am almost certain it was for a 50cc GY6, and I simply cut off the front end and adapted it to my header.
I made the header after finding the exhaust-port in the head on my Xingyue 150 is a FULL ONE-INCH inside diameter. The factory exhaust header was a SCANT 3/4-INCH inside diameter. THIS pretty much renders any better muffler system to no avail!
You CAN find 1" I.D. headers, but they're a little pricey, and you really have to search. They are also rigid, requiring perfect alignment of the entire system to prevent torqueing of the header/head joint.
I fashioned the header flange from a used John Deere or Onan generator header, with it's upper "stub" cut off, and the bend pie-cut and tightened.
Here are some pix...
Here's what the Johnny-Popper headers look like "as found"... LOL... I got these off eBay for $5+ $8 shipping. They are a full 1" I.D. and the flange is a perfect fit to the exhaust-port in my GY6 150 head. They ARE near BULLET-PROOF STEEL.
Here's the header with the upper "stub" which went into the block of the Deere flathead cut off and ground smooth. Also shown is the "pie-cut" I made to the inside of the bend, and then squeezed up to match the super-tight bend of the 3/4" factory pipe and had welded up. (This IS necessary to keep the header routed between the engine and frame, factory-style.) I was going to run the pipe in a gentle bend UNDER the frame, but that's NO GOOD. It puts the pipe too low, and it would hit any obstruction, damaging the engine. You have to keep it in the tight, factory position.
Here's the finished pipe, compared to the factory pipe. The main pipe is made from aluminized-steel flex-exhaust made for generators, implements, etc. It allows JUST enough flex to let you feed it through the frame, and align it with ANY system you like! The heat-wrap-tape is a MUST. It replaces the outer tubing on the factory pipe, which keeps the pipe from roasting the engine oil. I wish it COULD be routed UNDER the frame, BUT... you can't have the exhaust header the lowest part of the scoot, or you'll break off the cylinder first time you kiss a speed-bump.
Here are all the parts laid out for installation. You can see the unwrapped pipe here. The flex-tubing is a perfect "slip-fit" over the Deere header, and fused/sealed to it with "INFERNO"; a 2,400-degree header-repair material from Auto-Zone.
Here is the "finished" exhaust... Once you have a flexible 1-inch pipe exiting at approximately the factory position, you can easily "hook it up" to any muffler you can dream up, simply using auto-exhaust adaptors, reducers, clamps, or whatever you can envision. This old 50cc setup seems perfect for my 150. It's quiet as a mouse, and runs like a bear!
This is the "muffler" I adapted. (You could use a Briggs & Stratton, "Cherry-Bomb" glass-pack, shorty Harley muff... ANYTHING you like!) You're only limited by your imagination. I cut off the front header portion that bolted to the 50cc head, so it could hook up to the flex-pipe. For a mount, I used a single piece of 3/8" x 1-1/4" aluminum bar-stock, drilled to bolt to the factory muffler-clamp bolts. I fashioned muffler-clamps from the originals, using a BIG vice, and a BIG crescent wrench. Not too difficult, and GREAT exercise...
I anchored the cut-down clamp-rubber insulators to the tapered chamber with black Hi-temp RTV silicone. It blends right in. This particular system is feather-light, and "straight-through" with not one baffle anywhere. Nasty appearing, BUT very, VERY quiet.
My muffler-clamp bolts were STRIPPED from the factory, so I got new ones from LOWE'S. I tapered the ends, and cut grooves with a Dremel Tool and cutoff wheel to make the ends into "thread-chasers". It cleaned up the welded-on nuts, and worked like a charm! A good trick to remember on these scooters...
This thread is mainly a quickie "how-to" for making a full-diameter performance header that's flexible enough to make it EASY to attach to any muffler you may have. However, this little expansion/contraction chamber has proved to be perfect on my individual scoot. I already had the Mikuni carb main-jetted a tad rich, and the engine LOVES this system!
Hot in appearance, and totally straight-through with not a baffle anywhere, not even it the little glass-pack "stinger" muffler, it's a fooler! At idle, it's QUIETER than a stock muffler! (aparently the big chamber dissipates the velocity of the exhaust gas, so very little noise goes through the tiny red stinger-muff.) Under hard acceleration, it barks some, but nothing objectionable.
The UNI-sock filter actually makes more noise than the exhaust! Now THAT'S a quiet bike that won't irritate anyone. And, since it's many pounds lighter than the stock muff, it greatly reduces un-sprung weight! THAT is VERY good for handling. Now the rear wheel "scampers" across railroad tracks, instead of "staggering" over them... YUP!
The best thing about the sound of this is that it lost that "Asian" "blatt... blatt... blatt... sound, and now resembles the sound of an old Brit single thumper. Or a Briggs & Stratton lawn-mower... EEWWW... I prefer the "thumper" analogy... Anyway, it now sounds ALMOST like a proper engine, instead of a kitchen appliance... LOL!
After some brief test-rides, I'm FULLY convinced that any "improved" exhaust should begin with a full, 1-inch inside-diameter header. The small-diameter factory headers truly "strangle" the engine BEFORE the exhaust ever gets to any muffler. I can REALLY feel a difference in mine.
I truly hope this thread encourages some of you to help your engines breathe better!
Ride safe!
Leo (still wrenchin') in Texas
