Honda Spree and Elite 50 Forums

Like the title says what the differences in exhaust between a expansion chamber exhaust vs a regular performance exhaust. I was able to locate a expansion chamber exhaust for my Honda aero, however I have already purchased a ghost exhaust, will putting on the expansion chamber make a noticable difference to justify buying it and scraping the regular performance exhaust? I hear a lot of talk about it being the best, why and is it worth it, remember I have a 65cc kit and performance carb.

how big is the carb?

19mm with a pod filter.

yeah it should work good. i would go with the exhust tho.

when the mma tuners and such have an exhaust they usually make it to the specs of their engine. No one can really say if it is better unless you have all the specs needed and measured for the right exhaust to be made.The exhaust can be made for a certain amount of cc's and such but there are alot of other factors that are involved as well.

Agree with above. To add: tuned exhausts (like the one I built, see below link) work well at one set of RPMs. A chamber exhaust )like the stock one) works better on a broad range of RPMs.

Tuned exhausts will get you a lot more power in their band... for instance, if you're getting 3 HP from a chamber exhaust, you'll get 5 HP with a tuned pipe on the same engine... but only within a few thousand RPM of the design. It's hard to imagine unless you've ridden a bike with this type of pipe.

To be honest, from what I've seen the main advantage to aftermarket chamber pipes over stock is matching your overbore jug exhaust with the larger downpipe... and with some skill you can build your own setup, as many here have.

I am going to go with expansion chamber as being the best modification you can make to a two-stroke engine. An expansion chamber is pretty simple and also very complex. If it has an expander, chamber, reducer, and stinger... its a basic expansion chamber. Your exhaust pulse will move through the expansion section, and the wave will expand creating a negative pressure behind it as it expands. This negative pressure actually pulls unburnt fuel and air through the cylinder into the expnasion chamber. The exhaust pulse wave moves through the chamber and will eventually come to the recucer. This is the oppisite of the expander. The wave will be shrunken down to the size of the stinger. There will be reflected energy shot back towards the expander. This energy is echoed back by the reducer and will actually push the fuel air mixture back into the cylinder at a pressure higher than atmospheric pressure. Slightly supercharging. It gets very complicated because the angle of the expander and reducer, and the length and volume of the chamber all dictate at which RPM the strongest charge is reflected back. A tuned pipe will maximize the power band. Also complicated are second order waves that are shot back by the expander when the pressure is shot back by the reducer the first time. It happens on a much smaller scale but still factors into the physics of it all and affects the tuning of the pipe.

well if you are rally talking about the expansion chamber then you would also need to know the degrees of the expansion chamber. Seeing that it should be built for the cc that you are running the tuned length should be made for your bore. you can calculate the tuned length to see if it actually is made for the cc you are running. The degrees would predict at what rpm's your expansion chamber was made for and whether it would give you more power after your peak rpm or not.maybe you should ask for the specs on the chamber pipe so you can see what kind of riding that chamber pipe is made for.

There's an online expansion chamber design program linked in under perf. tech docs.