450 Nighthawk custom exhuast help

[nerfherder81]

I'm working on a 83 450 Nighthawk and want to ditch the stock exhaust, looking to build a custom 2 into 1 with a Yoshi pipe.
Some help I need is pipe sizing, length, things to avoid.
Also I want it to sound nice, I heard a Mac 2 into 1 on youtube and i was less than impressed. Am I going to be stuck with that sound (high pop pop) do to that fact it’s a 450 twin?
My bike sounds beautiful but it’s a 550 four.

Any help or suggestions or experiance with twins? Thanks

 

[fresh_c]

Not positive on the 450, but my 400 twin uses 1-1/2" double wall tubing as stock with a collector under the engine and long mufflers. I originally removed the exhaust from the collector back and welded on Emgo shorty mufflers. My bike was really loud and sounded like a pissed off lawn tractor. I've since rebuilt the exhaust utilizing the stock exhaust flanges and collars (which are double wall for the first couple inches) welded to 1-1/2" single wall exhaust tubing. It merges under the engine and exits out a shorty reverse cone muffler that DCC sells. I think it sounds good and a co-worker of mine described the sounds as almost Moto3. I'll take that as a compliment.

Try to keep the curves smooth and free from tight bends. I would suggest some sort of collector even if you run two mufflers. Don't forget to install the exhaust flanges before welding unless you are running a sleeve and springs.

 

[LongDistance]

Primary pipes should be roughly 1 size larger than the exhaust port. In this case the port is @1.2" so you would use 1 3/8" ID tubing. Honda's double wall pipe is actually 1.1" ID on the inner pipe. Primary pipe length for these engine is 33.25" measured from the valve stem to the end of the pipe. Shorter will help top rpm performance, longer will help low rpm performance. You can get a nice 2-1 collector from www.coneengineering. The secondary pipe should be at least 1/4 of the primary pipe length and 1.75 ID. Mufflers should be 10X the swept volume of 1 cylinder, 447cc's/2=223.5X10=2.23liters The exit of the muffler should be equal or less than the inlet, never larger. Smaller equals quieter
Some of this may not be doable with your project but the Primary pipe length and diameter shouldn't be changed.