Exhaust build?

[guest1590]

Hi,
I'm building a supermono race bike and could do with some advice on the exhaust system, twin port head. Pipe and silencer for each port? Or 2 into 1 but would struggle with noise levels with one silencer? Or 2 into 1 into 2 but would be more complex and heavier? I've seen 2 stubby silencers mounted under the engine on supermono's but don't understand how a very short system effects power delivery and still think that both pipes would need to join before the silencers? Could I mount one silencer under the engine and another mounted normally at the end of the system, a 2 into 1 with two silencers inline?
Any ideas?
Many thanks.

[guest295]

That latter plan sounds the best. No point in a thumper hauling around two exhaust systems.

[SteveC#222]

I have an article from the now defunct 'Thumper Page' forum about race prepping a GB500 ( partically the same as an XBR).  It includes some dimensions for a 2 into1 tuned downpipe system - I don't know if the system was any good, but it may give you an idea of where to start.  If you want a copy PM me your Email off forum and I'll send it to you.

[guest1590]

Cheers Steve,
I think I've got a plan now. 2 into 1 system is simple enough but keeping the noise down with a single race can is tricky without resticting the flow with baffles. Think I'm gonna fit a  small silencer under the motor and a large race can just beyond the footrest to keep the system short.

[SteveC#222]

Think I'm gonna fit a  small silencer under the motor and a large race can just beyond the footrest to keep the system short.

Which is basically what Honda fitted to the GB - a collector box between the lower frame rails going into a single silencer.

[guest564]

I would only go for a 2:2 on a race bike. I used to run a 2:1 on my XBR engine racer but as the noise regs got more and more stringent it was impossible to get max. power with one silencer. An old trick is to run unequal length pipes to broaden the power band.