Motorcycle Exhaust Length Theory

[Bigincher]

Originally Posted by haugster1340

Is there an equation to figure out the length of pipe one is to start with to achieve the performance desired?

Yes, there is a mathematical and theoretical formula for determining the optimum length of the exhaust pipe. I've stayed out of this thread, just watching it to see where it goes, and it's an interesting conversation!
The "formula" is so complex I don't think I can properly convey it in it's entirety, not until I have more time to properly brush up on the theory and type it all in here. However--- the information can be found in two excellent publications by 'Crystal Publications'. (You didn't think I knew this stuff by heart, did ya?) The first is entitiled "The Big Twin High-Performance Guide" and the second is "The V-Twin Tuner's Handbook". Unfortunately, these books went out of publication several years ago, and they are hard to find now. However, I have seen them on eBay at exorbitant prices! I bought my copies back in the early '90s when they were still cheap.
The 'High-Performance Guide' is the best publication I have ever seen in explaining and describing how to get the best power out of a V-twin motor. If you can find it, I highly recommend it. This is what the cover looks like........

[jolli1000]

Hello and thanks for this thread, it helpt me get my -28j run god.
i have just assambled it and made a set of pipes that ends just behind the gearbox, and the first thing i did was putting in Exhaust Baffles in the end of bouth pipes that is about 8-9" diferent in length. And that have coused me a really bad running engine that ran much richer and about half that hot on the one with shorter pipe, i had to dissamble to check the whole topend ,replace valve housings, pressure testing every thing .....