No other function on a 4-stroke (but obviously the engine needs to be tuned for it). have you ever started an nc30 up without a muffler?!Mananon wrote:Other than keeping noise down to a legal level, what other function does the can have?
The early 990cc motogp bikes mostly never used mufflers. But a lot of the riders complained about the sound level (as you would!) so mufflers started to appear. My vfr racebike is too loud not to wear ear plugs (ears will ring for a day if you don't - not good!), and it doesn't even come within a mile of how loud the motogp bikes are.
Twin pipes on the v4 obviously make the front and rear cylinder exhausts act independently of each other, so essentially you are designing a front and rear system for cylinders that are firing together (sort of acting as a single cylinder).
I have a full hrc race system on my track bike, and some of the impressions in it are beyond me (they look like big dents, but have seen them on other hrc systems). Exhaust design for optimum horsepower and/or torque is a science. There are many critical factors when it comes to designing exhausts it seems.
If you're serious about building your own, you should read up on some good books. As stated above, John Robinson's 4-stroke engine tuning covers the basics of exhaust design (and some mathematics behind it).
http://www.amazon.co.uk/Motorcycle-Tuni ... 857&sr=1-9" onclick="window.open(this.href);return false;
I've never read it, but I believe A. Graham Bell's 4-stroke tuning book is a reputable source of information also (I want this!).
http://www.amazon.co.uk/Four-stroke-Per ... 1844253147" onclick="window.open(this.href);return false;
I think if you head into your project blind you will do more to harm performance than enhance it. A quick bit of reading might make all the difference.
