expansion chamber physics equation needed

[perichbrothers]

Ok,
I was wondering about expansion mufflers or expansion chambers.
If an engine is a 66 cc,
what is the formula for how big the expansion chamber needs to be?

The exhaust explosion is way bigger than 66 cc right?

So I guess first off,
what is the actual displacement of the 66 cc engine?

then second,
what is the equation for exhaust displacement?


It seems that alot of the mailorder kits were made for the 49 cc engine,
so its actually not optimizing the bigger engine.
Was thinking of making one just for kicks.

Thanks alot guys.

TP

[wildemere]

Google Gordon Jennings or Graham Bell

Its all there.

There is also software that calculates pipe dimensions.

You will need some good data to input though.

Like exhaust temperature, fuel type, ect.

[perichbrothers]

Thanks wildemere!
This article is more than i'll ever need to know I think!

http://www.bridgestonemotorcycle.com...ou_really6.pdf

I was thinking there was a simple displacement equation,
but there is a ton of useful information in there.

The least of which will help not make my (potential) project not be a total waste of time!

Thanks again,

TP

[Homeless Bob]

Greetings guys..

Been reading to learn what not to do as I prepare for my first buy/build...

Thanks for all the help so far! Your sharing has educated this old man more than I could express...

As for the stuff by Jennings and Bell, I have a couple of links I can share.

The Two-Stroke TUNER'S HANDBOOK can be found here: www(dot)datafan(dot)com/TunersHandbook/2-strokefiltered.html

And

Performance Tuning can be found here : www(dot)kreidler(dot)nl/artikelen/performance-tuning-graham-bell/performance-tuning-graham-bell.pdf

Hope this helps!

[otis]

i have a grubee 48cc with the catalytic type black exhaust ho do i upgrade it and why wont my bike hit full rpms its like it has a govenor in it untii it maxes out at 45kmh, i already matched all ports, wide open burn is a nice tan on the plug how do i get that full throttle rpm up everyone give your 2 cents i would appreciate all help PLEASE HELP PLEASE HELP PLEASE HELP !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

[diceman2004]

A few links

SRW expansion chamber construction

this one has a free download ( scroll down to were it says free download
MOTA Two Stroke Engine Simulation Software

[gavmiester]

i have 2 66cc bikes and use 2 types of pocket bike chambers both work better than stock good low end torque like a trials bike motor