Building a better bucket (expansion chambers)

[gav]

Expansion chambers, hmmm... actually don't think they are too hard to build if you know what dimensions you need. What I'm looking at doing and have done before is build a mock one up from cardboard, what i need to know is the dimensions for each section. So the radius of each end plus the length means I can cut a section out of cardboard, roll it up and sellotape it to form a cone. Once I've my different cone sections made, tape them together as required to fit the bike , once happy with the shape etc, buy some sheet metal and some snippers and do the same, use the cardbord cones as a guide, trace them out on the sheet metal and roll them into the cones and weld them up. A thin gauge is pretty easy to work with. Then weld the cones together to form the pipe.
Heres some info on chambers and how they work http://www.motorcycle.com/mo/mcnuts/em-pipes.html
http://www.hpt-sport.com/tunedpip.htm
This a great view on how two strokes and their pipes work too http://www.southernskies.net/page_in...okeengine.html
So eventually should end up with something like this http://www.kawasakitriplesworldwide....g_mufflers.jpg

So anyway, seeing as I'm a lazy bastard can all you MB100 racers give me some info on dimensions of your pipes and any hints and info, photos be much appreciated as well, cheers!

[ajturbo]

lazy bugger!!!

[Skunk]

...give me some info on dimensions of your pipes and any hints and info, photos be much appreciated as well, cheers!

Sure - it's right here tuned pipes... as you know.

[gav]

see that word YOUR ?

[froggyfrenchman]

build a 4 stroke bucket my friend.... real engines have valves. lol each to their own . best of luck in the build.

[gav]

He he, you'll learn, so is that a rotary valve or a power valve?

[Wellyman]

Be careful with header pipe size, make sure you make it to factory length or you will lose power or something if you make the pipes too small.

[FROSTY:Me]

two stroke tuning. Ahhh such a black art form

[froggyfrenchman]

scream out if you need any tube for headers gav. im an engineer in nz biggest user of tubing. Furnware furnature. so its all nice light guage- get real hot quick stuff. NB: frog oppreates bender, has been known to perk many a custom exhaust...

[Skunk]

see that word YOUR ?

yep, but I also read the bit on the site that said copying someone elses' will NOT produce the best pipe for YOUR setup and requirements...

This of course is not even considering whether or not the exhaust and transfer port timings and outlet areas have been optimized for expansion chamber use.

and

Proper design of even a simple expansion chamber is somewhat of a black art, even though formulae exist that will get you in the ballpark (there is quite a bit more to this than simply choosing the appropriate angles and lengths based on sonic velocity - everything about the pipe comes into play, including the headpipe diameter and length, and the tailpipe ('stinger') diameter and length).

Good luck anyway...

[Bert]

Expansion chambers, hmmm... actually don't think they are too hard to build if you know what dimensions you need. What I'm looking at doing and have done before is build a mock one up from cardboard, what i need to know is the dimensions for each section. So the radius of each end plus the length means I can cut a section out of cardboard, roll it up and sellotape it to form a cone. Once I've my different cone sections made, tape them together as required to fit the bike , once happy with the shape etc, buy some sheet metal and some snippers and do the same, use the cardbord cones as a guide, trace them out on the sheet metal and roll them into the cones and weld them up. A thin gauge is pretty easy to work with. Then weld the cones together to form the pipe.
Heres some info on chambers and how they work http://www.motorcycle.com/mo/mcnuts/em-pipes.html
http://www.hpt-sport.com/tunedpip.htm
This a great view on how two strokes and their pipes work too http://www.southernskies.net/page_in...okeengine.html
So eventually should end up with something like this http://www.kawasakitriplesworldwide....g_mufflers.jpg

So anyway, seeing as I'm a lazy bastard can all you MB100 racers give me some info on dimensions of your pipes and any hints and info, photos be much appreciated as well, cheers!

GAV I've downloaded a bit of software - once you enter in all the port timing bit and what RMP you want it spits out the required dimensions Note it only a demo version but when i entered my buckets info i nearly matched what i'd calc'ed from the tuning bible.

check out www.iwt.com.au and look at downloads - there's one called chamber design utility

go to the mota tab / moto info on that page there is is download about 1/2 way down.

[dangerous]

Gav, you are more than welcome to use my chamber as a patten.... but I have no idea what state of tune the engine is re: porting etc.

[laRIKin]

two stroke tuning. Ahhh such a black art form

To true.
It takes a lot of testing and fiddling to get them right.

A mate of mine tried to make a pipe for his RS125.
He spent months working it out and weeks making it.
Put it on the Dyno and it was crap, so in to the rubbish bin it went.
As he did not have the heart to try again after all his work.
Pity really as he is a good trades man and usually a real trya .
After all at one stage he built a complete frame from scratch.

Try by all means and I'm not trying to put you off.
But do not expect to get it perfect first time and try to build in the design
changers you can make to the pipe as you go along.

Best of luck
Rik

[texmo]

http://science.howstuffworks.com/fra...skito1_04.html

[gav]

yeah thanks guys, seems I'm gonna be the first person ever to build a pipe for a MB100, :slap: just thought someone might want to share some info as a starting point, oh well....