Expansion Chamber possible?

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SlicerDicer

Guest
http://www.davesmotors.com/store/product1708.html

I am considering getting that expansion chamber when it comes back in stock. I will need to do a bit of modification as philcred did but I think this one is quite similar. Its cheap enough too.

And the silencer is replaceable that is nice for when garbage builds and blocks it.
 


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custom_tecumseh

Guest
What advantages do these provide. I see them on 2 stroke dirtbikes an such...

Is it comparable to aftermarket headers/exhaust on a car.

Performance, efficiency, sound and such?
 
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SlicerDicer

Guest
it controls the sound waves and pressure waves or something like that to force air into the engine doing a super/turbocharger like effect. It usally only targets a special rpm number to give maximum performance. Most of the time they are custom created per engine but with these we have to take what we can get :D

BTW feel free to slaughter my explanation if I am wrong
 
O

OldPete

Guest
SlicerDicer said:
it controls the sound waves and pressure waves or something like that to force air into the engine doing a super/turbocharger like effect. It usally only targets a special rpm number to give maximum performance. Most of the time they are custom created per engine but with these we have to take what we can get :D

BTW feel free to slaughter my explanation if I am wrong
You are close enough. :D :cool: Google Gordon Jennings and read one of the first four hits that will explain expansion chambers in great detail.
 
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Herrmanator8

Guest
on my kx85 and our cr250 it seems to me that the purpose of the expansion chamber is when the powerband kicks in, it allows the exhaust to flow freely so that the engine can run at extremely high rpm's. im not shure about this but it seems to be useful...

jon
 
J

Joshboy

Guest
what would happen if i just took off the exhaust pipe completely?
 
A

Alaskavan

Guest
I haven't Google'd Gordon Jennings, but my guess is that it "might" improve bottom end performance and seriously decrease top end performance. Oh yeah. It would probably p*** off the neighbors, and perhaps invite official intervention.
 
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andyinchville1

Guest
Removal of the exhaust system typically results in less low to mid range power BUT improves top end....Not to mention being a "bit" louder! ;-O

Andrew
 

azbill

Active Member
Joined
Dec 15, 2006
Messages
3,721
no exhaust can also mean running lean
air gets sucked in through exhaust port :eek:
lust a word from experience :LOL:
 
G

Ghost0

Guest
I think SlicerDicer is close, but I think I would get this pipe instead.
http://www.davesmotors.com/store/product1617.html
Some mods will be required but it will be a huge improvement over stock. Because it was not made specifically for the motor/carb combo (70cc China unit) some tuning will be required. Depending on many variables, gear ratio especially, you will either need to increase or decrease the distance from the exhaust port to the end of the pipe. The shorter the pipe, the more top end and the longer the pipe, the more bottom end. If I had to guess, since the pipe was made for a 49cc engine, I would start with it longer and shorten it an inch at a time until you reach your desired results. You can use fiber reinforced silicone tube with hose clamps for your tests so you don't have to weld it every time. I know I will be buying one as soon as I get my moto-bike complete.
 
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