Exhaust Want to find a decent exhaust

[Steve Best]

Excellent SR! Thanks for the work and pictures.
Glad you took the time to cut the Banana pipe apart.
I tried one and couldn't figure out why it didn't work. I figured it must be baffled.
Terrible baffle design, but the headpipe only could be cut off and rewelded to work without the baffles.

Steve

 

[Street Ryderz]

That is what I was thinking and adding some belly to it!

 

[Deleted member 12676]

The more I know, the more I hate the dealers. The seller of the banana pipe should be telling customers that it looks like a normal expansion chamber but isn't.
Here's a drawing of my motorcycles original pipe. It worked very good at boosting the power and spreading it over a broad powerband. Only problem is the the chambers exit hole was starting to get smaller from carbon buildup which would make it more and more restrictive as time went on.

 

[butre]

I've been telling people for years that those banana pipes do jack s**t, now I've got photo evidence

 

[BilalCarroll]

Well if you want a better one but still want it quiet you could get this one:
http://www.ebay.com/itm/141809800334

 

[Street Ryderz]

Unfortunately that one is not any better!If you need longer header length the sick bike parts kit is much better.

 

[Steve Best]

I have that exact pipe in chrome. Paid $35cad or about $25us for it.
Very slightly increased power and more noise than my favorite $20cad / $15us chrome muffler from
http://www.motorizedbicycle.ca/exhaust-system.html:
(oops! just noticed they have stopped selling them. No great loss)

Available at http://www.motorizedbicycle.ca/exhaust-system/chrome-exhaust-muffler.html
Look at some of my past post about this and the Banana pipe.

I am working on the Banana pipe to get more out of it right now actually.
The flange is good but the screw connector is very restrictive.I've drilled it from 15mm to 19mm and we will se how it works.

Steve

 

[GreenMantis]

The stock exhaust is entirely inappropriate for a 2 cycle engine, as it has no expansion chamber. I think what I want to try is this banana looking expansion chamber, but I want to chop the muffler off the end of the stock exhaust, and weld that right to the end of the banana, otherwise it'll be way too loud, and I'm not really into loud. I have had many 2 stroke dirt bikes, and that was the setup they all used: an expansion chamber with a silencer on the end of it. I'm not going to screw it up by cutting the tiny spout off the banana, either, it needs that. 2 cycle exhausts are an art: they are supposed to resonate internally in such a way that part of the blast is reflected back towards the cylinder, and they need that to run right. It needs the smaller diameter spout to speed up the exhaust flow at the outlet.

 

[Frankenstein]

The stock exhaust is entirely inappropriate for a 2 cycle engine, as it has no expansion chamber. I think what I want to try is this banana looking expansion chamber, but I want to chop the muffler off the end of the stock exhaust, and weld that right to the end of the banana, otherwise it'll be way too loud, and I'm not really into loud. I have had many 2 stroke dirt bikes, and that was the setup they all used: an expansion chamber with a silencer on the end of it. I'm not going to screw it up by cutting the tiny spout off the banana, either, it needs that. 2 cycle exhausts are an art: they are supposed to resonate internally in such a way that part of the blast is reflected back towards the cylinder, and they need that to run right.

View attachment 79317

My weedwhacker doesn't have an expansion chamber I'm going to call them and let them know how inappropriate this is.

I am not sure but that looks a lot like a muffler that did a bad job at behaving as a good expansion chamber.

 

[Deleted member 12676]

the banana pipe is not a normal expansion chamber. It's internals are different.
Yes most dirt bikes have expansion chambers but they also have gears.
A 1 gear engine needs a broad powerband. A typical expansion chamber has a 1500 - 2000 RPM powerband and it creates a 1000 RPM band of below normal power just under the pipe powerband. I now know the best design of pipe for these china girls but I haven't put it on my site yet.