Help needed GP460 muffler

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Dec 18, 2011
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I just put on a new gp460 on my catrike Road and took it for it's inagural ride this afternoon. It is VERY fast and flies up hills.
But it is extremely loud, which I expected. I tried the stock muffler and then put on an aftermarket muffler but neither really help much.

Has anyone found a good muffler that really dampens the sound? Ive heard a motorized bike ride by that sound like it was underwater.....just a gentle gurgling sort of sound. Granted it wasnt a 2 cycle HO engine but there has to be something better than what I am hearing right now. With earplugs it isnt unbearbale but I would really like to muffle a LOT.
 
My 460 engines were loud too with stock muffler. I tried the 460 Dominator, still loud. I also tried ADA S1 pipe, much quieter.

Then I bolted on an SBP Happy Time expansion pipe.

The engine became so quiet, I swear I could hear the piston ring scraping the cylinder @ idle!

I thought I'd LOSE power, because the pipe's exhaust flange was GROSSLY mismatched with the 460 exhaust port. Surprisingly, it made a goodly amount of power. Maybe not as much as the Dom, especially @ high rpm, but there was power to spare.

My friend reworked a 460 Dominator pipe to work on his rear-engined bike. With it, his top speed was 53mph on flat ground.
 
My 460 engines were loud too with stock muffler. I tried the 460 Dominator, still loud. I also tried ADA S1 pipe, much quieter.

Then I bolted on an SBP Happy Time expansion pipe.

The engine became so quiet, I swear I could hear the piston ring scraping the cylinder @ idle!

I thought I'd LOSE power, because the pipe's exhaust flange was GROSSLY mismatched with the 460 exhaust port. Surprisingly, it made a goodly amount of power. Maybe not as much as the Dom, especially @ high rpm, but there was power to spare.

My friend reworked a 460 Dominator pipe to work on his rear-engined bike. With it, his top speed was 53mph on flat ground.

I assume the pipe is larger than the exhaust port? not smaller? But the bolts are spaced the same?
Can you give me a link to the Happy TIme pipe youre talking about?
 
BTW, Im only getting about 40mph with mine but after riding a Honda35 it feels like a rocket. Man it is FUN! I wish Id gotten an earlier start today so I could have ridden for hours. Also I glanced somewhere you had a 4 liter gas tank for yours? Can you link me to one of those too? Also what kind of mpg do you get from yours?
 
I assume the pipe is larger than the exhaust port? not smaller? But the bolts are spaced the same?
Can you give me a link to the Happy TIme pipe youre talking about?

Actually, the SBP exhaust pipe flange is smaller than the 460 port. Not only that, but the 460 port is rectangular and the SBP pipe is round!

I also installed the pipe on my Tanaka 47R racing engine. Its port was MUCH larger than that same SBP pipe. However, it also quieted the 47R and made more power than a stock 47R muffler.

http://www.sickbikeparts.com/catalo...ducts_id=83&osCsid=7p36hl5q4is15u860panq09nb1
 
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BTW, Im only getting about 40mph with mine but after riding a Honda35 it feels like a rocket. Man it is FUN! I wish Id gotten an earlier start today so I could have ridden for hours. Also I glanced somewhere you had a 4 liter gas tank for yours? Can you link me to one of those too? Also what kind of mpg do you get from yours?

My friend Rick also used a Honda 35, then upgraded to a CY460 engine. He's running 53mph on the flats.

What's your gear ratio or spindle size?

I got about 65mpg on the 460 with friction drive. I got about that same mpg with the 460 ANNND the Tanaka 47R engine with Scooterguy drive and shift kit. However, I shelved the 460 and stuck with the 47R. Now after a series of improvements, the Tanaka is getting about 125mpg.

FWIW, the 460 is more powerful and has greater potential than a stock 47R. I sidelined it because of its unreliable clutch. When I find a dependable clutch, I'll use the 460.

Here's the 4-liter tank. It

http://www.ebay.com/itm/bicycle-Mot...Cycling_Parts_Accessories&hash=item256aeebc3e
 
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Actually, the SBP exhaust pipe flange is smaller than the 460 port. Not only that, but the 460 port is rectangular and the SBP pipe is round!

I also installed the pipe on my Tanaka 47R racing engine. Its port was MUCH larger than that same SBP pipe. However, it also quieted the 47R and made more power than a stock 47R muffler.

http://www.sickbikeparts.com/catalo...ducts_id=83&osCsid=7p36hl5q4is15u860panq09nb1

Ok, so I am clear.
The pipe does completely cover the port exhaust right?
or is some exhaust still coming out at the port?
And the flange bolts are spaced the same as the exhaust port holes so it matches up nicely? A
nd do you have a photo of your setup? I
would like to know where it will be positioned.
I would really appreciate it.

Im getting ready to go all the way down to the Keys and dont want to be deaf when I get there. And I would also just as soon not draw un-necessary attention to the trike by the noise as well. I hear the cops are tight down there.
 
My friend Rick also used a Honda 35, then upgraded to a CY460 engine. He's running 53mph on the flats.

What's your gear ratio or spindle size?

Not sure. I dont know the gear ratio of the gear box so I can't calculate it. Im running 72/20 on the other gears though but whatever it is, I like it. I have 20 inch wheels and it is geared right where I want it.
My only concern at this point is noise.
 
Id guess it was 5 to 1 and with the 72t and 20t gears that would be 18 to 1 right?

Yes, 18:1 would be correct with 26" wheels @ 9300rpm. If it was that simple, there'd be more power/rpms to go faster.

However, with your 20" wheels, your effective gear ratio is 23.4:1 @ 12,500rpm. That's why you can't go any faster. You're way past your redline @ 40mph.

Swap your sprocket from 72t to 63t for more speed. At that same 12,500rpm, speed of 47.2mph is theoretically possible.

With 26" wheels, it'd be 15.75:1. However, with 20" wheels, your effective gear ratio is 20.5:1.
 
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