Headers/Mufflers So Short

[OakBehringer]

Would running short mufflers on headers this short result in a noticeable performance degradation?

http://www.bikeexif.com/yamaha-xs650-2

Thanks,
Adam

 

[Ghetto]

I would say there would be minimal loss if any.

 

[XSLeo]

With proper tuning you can get them to work. Not as well as a longer exhaust but ok.
Generally speaking the shorter exhaust moves the peak power up the rpms. So far up the rpms you will never reach the peak power.
Leo

 

[OakBehringer]

With proper tuning you can get them to work. Not as well as a longer exhaust but ok.
Generally speaking the shorter exhaust moves the peak power up the rpms. So far up the rpms you will never reach the peak power.
Leo

OK, OK, I thought I had read something like that before. Does anyone have any data, numbers, or less-than-arbitrary advice in this regard?

 

[OakBehringer]

That's probably asking for too much. Maybe just some personal experience?

 

[5twins]

Some of the important factors in an exhaust system design are length, headpipe I.D., and muffler volume. That set-up lacks all 3 so I would imagine it's way down on power. If you'd like your 650 to perform like a Honda 350, go ahead and use a system like that, lol. Either that guy blew all his money on the front end or he's an "artiste" going for looks over performance.

 

[XSLeo]

From what I recall a head pipe of 1.5 inch diameter 29 to 36 inches is about right. Make it the 36 inches, then test it, On a dyno is best, cut it off an inch, retest, cut retest. It should change the way it runs with each cut, Usually gets better, At some point the power will start to drop off. Now add the inch back in. Either weld it back or build a new set of headpipes at that length.
As you test look for power in the range you ride, not peak power at 8000 rpms.
Me, when I build mine I plan to go for them a bit on the long side, better lower end performance. Somewhere in the 33 to 35 inch range.
If you Google exhaust building, you will find a lot on the theory of building an exhaust. What works and why. May get very technical.
Leo

 

[CDNTX650]

i can tell you i tried running a straight for a while on my 81GPz 1100, and the loss of low end TQ was very noticeable. Unbelievable how much better it was with the yoshimura pipe on.

 

[bbillington]

Some of the important factors in an exhaust system design are length, headpipe I.D., and muffler volume. That set-up lacks all 3 so I would imagine it's way down on power. If you'd like your 650 to perform like a Honda 350, go ahead and use a system like that, lol. Either that guy blew all his money on the front end or he's an "artiste" going for looks over performance.

It's from a very boutiquey shop, if you will, more form than function. That said, they seem to be making a business out of building bikes and bike-themed items, so good for them.

 

[XSLeo]

There is a lot more to an exhaust system than just letting the exhaust out of the engine. When properly designed, the out going exhaust helps the engine draw in more incoming fuel/air mix.
More in and out, you get more power.
Leo