How to bend a custom exhaust for 81' 850GL

[Anonymous]

My brother just picked up a tube bender and I was thinking of bending pipes for my 81' 850gl. Should I do 4 into two, 4 into 4, or what. How necissary is the crossover. How much baffling should I include to make the pipes sound good. Does anyone have any tips for painting pipes black. Thanks.

[HiSPL]

The crossover pipe is not necessary, however if can put one in it should give you a little more torque and overall smoothness. A 4-4 would be righteous. VH-1 makes header paint that works real well. I painted mine blue and they are pretty cool looking. Most bikes have about 12-16 inches of baffle area, give or take. More baffle means less noise. One trick for placing your crossover pipe is to paint your pipes with regular(not hi-temp) paint and run the engine for a while. Check to see where the paint bubbles up. That is a hot spot and will be a great place to locate your X-over pipe. The paint will bubble close to the engine too but don't worry about that. You need a location that is closer to the middle of the bike. Like where suzuki put it.

[Anonymous]

Yeah I think that I'll go with the 4 into 4 just to see what it looks like. Should I increased the pipe diameter after I get under the foot pegs.

[argonsagas]

There is more than a little theory, and a lot of data available on exhaust systems.

Generally, it would be best if you left the diameter the same throughout, and it is very important that each pipe match the output of the engine.

This might mean you do not use a larger diameter, but a smaller diameter outlet instead, to provide some backpressure that would improve the engine output and the exhaust flow.

Again, generally speaking, this would be the same for each cylinder thus, you should ensure all 4 pipes are bent and routed to allow you to match the overall lengths, and using minimum bends to maintain the smoothest possible exhaust flow within them.

Everything above is general only. You need to sit down and answer a lot of questions as to what you want to achieve, and how you drive , then fit those against the bike you want to drive.

While it may not be likely, you may find the tests suggest you need a detuned Honda Dream 360 instead of a 1150 GS.