exhaust pipes

[Divers]

Disclaimer - No flaming! I am learning.....

So.....going to use the stock manifold and first pipes (2-1) for my 81. However, was thinking (guessing) that I would just run a straight pipe back to...........WAIT FOR IT....WAIT FOR IT......a Harley pipe. My father just upgraded his Harley pipes and has these brand new old ones just sitting around.

Is this crazy, stupid, shortsighted, genius.................be kind!

[maytag]

do it. and let us know how it goes!

I've been toying with the idea of motorcycle pipes for mine too. But I'm thinking more in the vein of sport-bike pipes.

a general rule of thumb for determining flow-capacity is HP numbers. Coming-off a Harley, those pipes aren't gonna be designed to flow huge numbers.... but either are our TC motors.... so unless you;ve got a lot of performance modifications, you should be good-to-go.

[So Cal Mark]

what is the diameter of the pipe?

[Divers]

Good question....I will have to check...

[So Cal Mark]

if it's not at least 2" don't waste your time

[blurple124]

My exhaust pipe is 1 3/4" but gets down to 1 1/2" in some spots, is this smaller than stock? Or is it restrictive, and this is why you suggest a 2" minimum?

[Divers]

They are 1 3/4 so I am still thinking about this plan.

[basarabam]

do it. and let us know how it goes!

I've been toying with the idea of motorcycle pipes for mine too. But I'm thinking more in the vein of sport-bike pipes.

a general rule of thumb for determining flow-capacity is HP numbers. Coming-off a Harley, those pipes aren't gonna be designed to flow huge numbers.... but either are our TC motors.... so unless you;ve got a lot of performance modifications, you should be good-to-go.

Modified exhaust manifolds to run dual exhaust? Considering a GSXR 1000 is half the the displacement but more HP would be interesting to see how Yoshi's would perform and sound.

My 2006 GSXR had a valve just before the pipe that opened and closed to manage exhaust flow I believe but not completely sure what controlled it.

[maytag]

Modified exhaust manifolds to run dual exhaust? Considering a GSXR 1000 is half the the displacement but more HP would be interesting to see how Yoshi's would perform and sound.

My 2006 GSXR had a valve just before the pipe that opened and closed to manage exhaust flow I believe but not completely sure what controlled it.

I haven't measured the diameter of a liter-bike pipe, but pretty confident it's near 2". And most aftermarket setups (race-pipes) for liter bikes are single, not duals. they're running 200hp-ish through a single "muffler".

The valve you are describing is a "power valve". it was designed to induce back-pressure (more importantly; the pulse-wave) at certain low-RPM situations in order to increase low-end torque. Not something that gets left on the bike with an aftermarket exhaust, and certainly not something you;d carry over to an application such as we're discussing.

[basarabam]

Yeah I was just mentioning it.

Only reason I was saying dual was in reference to the displacement. I know that when I built my Mazda I made the mistake of going 3" exhaust and lost power due to not enough back pressure but wasn't sure if an exhaust pipe designed for 1 liter would allow enough flow for a 2 liter motor. I guess I meant it more as a question than a statement. I see you mentioned that flow needs for a motor are determined by the horse power, so displacement doesn't factor in?

[maytag]

I see you mentioned that flow needs for a motor are determined by the horse power, so displacement doesn't factor in?

well, it does and it doesn't.
for the purposes of this sort of calculation, HP is a function of "flow". HP is always a function of cylinder pressure and volume. this is true of normally aspirated and boosted motors alike. So a system capable of flowing 200hp in a 1-liter motor would still be capable of flowing 200hp in a 4-liter motor. (remember, these are rough ball-parks)

the thing to remember here is that the 1L sportbike is making it's 180hp at 12k-14k rpm, roughly double the RPM range of our 2L (or 1.8L) motors.

[basarabam]

Would it hurt using 2 smaller pipes to use dual mufflers or would I want to use 2 inch on both? I had dual Vance and Hines pipes on my 750 Ducati with a home made exhaust and it sounded amazing with the V twin.