Exhaust question

[ChristoT]

Hello hello

I have a question about exhausts.

How big an end can can I stick on my ZX400? Because it's a grey import, and a 1988 model (!) there is next to nothing out there for it. Also, I have a bit of a thing for Akrapovic carbon cans - a proper carbon subbie looks gorgeous.

However. My bike is only a 400cc. My question is, how big a can can I stick on before it gets ridiculous? I suspect a can designed for an R6 would sort of work, but the one designed for the VFR1200 would be over the top. Or doesn't it matter? Help?

BTW, I'm talking about gas flow here rather than physical size!

[Dead Eye]

Surely it would make sense to match the pipe diameter to cans available? Shouldn't be hard to do - many eBay sellers list the dimensions of the cans input

[ChristoT]

Surely it would make sense to match the pipe diameter to cans available? Shouldn't be hard to do - many eBay sellers list the dimensions of the cans input

TBH, I'm not entirely sure what the diameter is! I know the OD, but not the thicknesses. I'm looking at Ebay as I like tuning on the cheap, and the cheap cans aren't the most detailled posts!!  As for a link pipe, I'm sure I'm be able to make one at work, or find a place that can make one for me. 

[Dead Eye]

A tape measure is pretty useful and probably costs £1 at most...

Even then, you are probably talking 1-2mm of metal wall thickness so its not hard to guesstimate really

You're other option is to try to find if any other bikes have the same size exhaust and look for options from them.

[ChristoT]

A tape measure is pretty useful and probably costs £1 at most...

Even then, you are probably talking 1-2mm of metal wall thickness so its not hard to guesstimate really

You're other option is to try to find if any other bikes have the same size exhaust and look for options from them.

The thickness doesn't bother me hugely, as I can always make a link pipe to fit. I just don't want to kill the engine with too much backpressure, or too little.

[glynblue2]

The less restriction on a 4 stroke engine the better, backpressure does not effect a 4 stroke the same way it does a 2 stroke where back pressure is a requirement to make the angine run a 2 stroke engine the only problem with a 4 stroke is if you restrict it by producing back pressure then it kills the out put so the less restriction the better.
 

[ChristoT]

In theory...

In practice, even 4s need a bit of back pressure. Take the end can off a Fazer, it will only rev to circa 6000rpm.

[Grahamm]

My question is, how big a can can I stick on before it gets ridiculous?

FYI

Insanely Huge Exhaust On Motorbike