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I have a 99 M750 that I race in classes that suit its modest capabilities.
I'm thinking about doing something to the exhausts, they stick out more than they need to which limits ground clearance, and they're not exactly light. Someone has hacked them about a bit to let a bit of noise out.

I have a couple of ideas that would use the original cans and systems- both involve shortening the cans and coring them.
One is to shorten them so they finish before the axle nuts, and them heat bend the system so that the cans are tucked in as cloase to the swing arm as possible. The other plan is to shorten them again, but make link pipes so they can be tucked up under the pillon grab rails.

I have a couple of other devious plans... my questions are:
  • what exactly is the concept behind 2 into 1 into 2 systems, and 2 into 1 systems?
  • And what would be the effect of making a 2 into 2 system with no balance pipe?
  • What does the balance pipe in a 2 into 2 system actually do?
  • Most of the MotoGP machines seem to have a short total system length ending in a megaphone. The pipes for the front cylinders typicaly pop out under the bike just infront of the back wheel, and the pipes for the rear cylinders seem to exit under the seat at the back of the bike. Does anyone know if they use link pipes?

Sorry if this is all a repost, I searched for a while and couldn't find anything specific.
 

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Great questions.
In any twin, the most torque will be achieved by a two-into-one system. Seat of the pants (and launching out of corners) this is by far the way to go. (Sorry, Ducati.)
Two-into-two systems will probably make more horsepower at the top of the rev range, but will almost certainly cost low to mid-range torque. The same can be said of very low backpressure systems, such as short-tube styles and those with no mufflers. (A possible advantage on fast tracks with long straights.) The crossover pipe helps equalize gas pressure from cylinder inequality, and is a must. (It also helps torque numbers. )
Moto GP bikes have four cylinders (Ducatis are a rare exception to this rule) and exhaust tuning is a bit different. They typically make more horsepower and less torque than a twin of equal displacement, and can take advantage of this by running un-muffled four-into-one or equalized four-into-two systems. It doesn't matter quite so much about losing torque when you have a high-rpm hp advantage and can run WFO on the track. This is also why most of the street versions of Japanese Superbikes now run active EXUP style exhaust system valves. This is the most efficient way known to get the best of both worlds--a valve that increases backpressure, thus increasing torque at lower rpm's, while offering the ability to open up at higher revsto increase horsepower.
Ducatis are torque-monsters (no pun intended) by nature, and can get away with dual cans. If you were designing a 2-1 system and wanted optimum results you'd need to factor in cam profiles, airbox volume, compression ratio, actual displacement, and a far smarter dude than me to do the math.
On a budget? Chop your cans, bend 'em up for clearance, make them look as groovy as possible, and eat more salads. GO HAVE SOME FUN! [thumbsup]
 

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On a budget huh, me too. Here's what I did for about $150 total. I initally felt an increase in the upper revs. I think that was because at first I reved the snot out of it just cause it sounded so much better. The more I rode it the more I felt an increased throttle response through the whole range. I haven't dynoed it yet, but after I open the airbox and get a PCIII, I will.

http://www.ducatimonster.org/smf/index.php?topic=70560.0
 

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Ducati Pilot said:
Great questions.
In any twin, the most torque will be achieved by a two-into-one system. Seat of the pants (and launching out of corners) this is by far the way to go. (Sorry, Ducati.)
Two-into-two systems will probably make more horsepower at the top of the rev range, but will almost certainly cost low to mid-range torque. The same can be said of very low backpressure systems, such as short-tube styles and those with no mufflers. (A possible advantage on fast tracks with long straights.) The crossover pipe helps equalize gas pressure from cylinder inequality, and is a must. (It also helps torque numbers. )
Moto GP bikes have four cylinders (Ducatis are a rare exception to this rule) and exhaust tuning is a bit different. They typically make more horsepower and less torque than a twin of equal displacement, and can take advantage of this by running un-muffled four-into-one or equalized four-into-two systems. It doesn't matter quite so much about losing torque when you have a high-rpm hp advantage and can run WFO on the track. This is also why most of the street versions of Japanese Superbikes now run active EXUP style exhaust system valves. This is the most efficient way known to get the best of both worlds--a valve that increases backpressure, thus increasing torque at lower rpm's, while offering the ability to open up at higher revsto increase horsepower.
Ducatis are torque-monsters (no pun intended) by nature, and can get away with dual cans. If you were designing a 2-1 system and wanted optimum results you'd need to factor in cam profiles, airbox volume, compression ratio, actual displacement, and a far smarter dude than me to do the math.
On a budget? Chop your cans, bend 'em up for clearance, make them look as groovy as possible, and eat more salads. GO HAVE SOME FUN! [thumbsup]
wow...great info!
 

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I've built 2 into 2 and 2 into 1 systems with various pipe configurations & I couldn't tell any difference. The only person that I'm aware of who has dynoed different systems on the same bike is Doug L and he claims that 2 into 2 is superior. The 2v motors don't seem to care much about pipe length, configuration, or crossovers. I'm sure there is a difference but it's got to be pretty small. As for heating the pipe to bend it, I think you'll probably just kink it, try cutting it part way thru then bending it where you want it & welding it back up.
 

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I had 3 different configurations on my '99 m750. I will rank these for you as follows below:

Best power gains:
Hi-mount Remus CF - with lots of other work, dynoed at just under 70 hp
2-1 DP Megaphone 'race only' full system- -2 hp from the Remus

Don't know about the FBF - didn't dyno it.

I know you didn't specifically ask, but FWIW:
Best sounding:
2-1 DP 'race only' Megaphone full system - very raw and evil - just right for the bike I was trying to make.
Hi-mount Remus CF - nice and bassy dry thump to the exhaust note
Low-mount FBF CF - similar to the Remus but a bit more quiet

Interestingly, the Remus CF gave me fuel efficiency in the low 30s mpg. The megaphone nearly doubled that - I had stretches where I was over 60 mpg, and I probably averaged in the mid 50s. I know this is a tuning thing, but both systems were dynoed and the exhaust was analyzed to make sure it wasn't running incredibly rich or lean through the power curve.

Check the sponsors classifieds area - I got the 2-1 megaphone for $500 from AMS last year - they may still have a couple for sale.
As it was designed for a m900 with slightly larger heads, the header section needed tweaking to fit properly on the m750.

Feel free to PM me more questions if you've got 'em. I've got photos too if you're interested. [thumbsup]
 

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Discussion Starter #8
BIG thanks to everyone who has replied. Some interesting info there.
VermontDuc and coastie- yep, always on a budget. the NZ dollar is worth about $0.65US, yet for every dollar someone doing my job in the US would earn, I'd still only get one NZ$ :'(

Ducati Pilot- thanks for the interesting info. You can probably tell that I was toying with the idea of having seperate systems for each cylinder. So I'd have a short system under the bike exiting just in front of the back wheel, and another under seat system of the same length serving the rear cylinder. Just FYI, there used to be a site called the Yamaha Design Cafe which gave a lot of info on the 'milestone' bikes like the FZR and R1 etc. The blurb went into the operation of the EXUP valve in some detail, and apparently it wasn't so much to do with back pressure as altering the timing of the +/- pressure pulses to make the engine more powerful throughout the rev range. I had an 89 FZR1000, and I can tell you that with the valve disconnected and held wide open, the bike sounded great, but had much less power in the bottom end and mid range.

Norm- so based on that a seperate sysem for each cylinder as described above might work...

Supero100- eeeeeexcelent, expect a PM soon.
 
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