I've been following along, & even rarely commenting on the dual exhaust threads in the past... here's some things I "think" I've learned over the years...

Exhaust pipe diameter, directly effects the power profile of the engine... in general, on a 4 stroke engine, a smaller diameter exhaust pipe, is more conductive to creating higher torque outputs... a larger diameter exaust pipe, is more conductive to creating higher horsepower outputs... running a "stepped" ( increasing diameter ) pipe as in the Big Gun, & some other systems, can give a good balance of both... I'm leaning towards using the same diameter, or slightly larger pipe as stock...

Generally speaking, the exhaust pipes should be of equal lengths...adjusting the "back pressure", through a disk system, similar to the Super Trapp's, type of disk system, both allows the dyno tuning of the exhaust, for maximum power, & can be used to "tune" the exhaust to simulate equal lengths of pipe... the disadvantage of the disk type systems, is increased maintenance, both in carbon build up on the disk retaining screws threads, & carbon / mud build up on the disk gaps themselves ... what this amounts to, is the fact that the system must be "serviced", roughly every few weeks, or every time that the system is exposed to excessive dirt, moisture, or mud...

At this point, I'm still trying to decide if I want to modify the "stepped" exhaust pipes of my current Big Gun system, or weather I want to start over, & have pipes manufactured at my local exhaust shop, & send them out for Jett Hot ceramic or similar coating... retaining my Big Gun system as a back up ??? I'm leaning towards having my own pipes produced... they will both exit from the left side of the quad, & will likely contain either a pair of Super Trap IDS-2 slip on chambers, or a pair of my own chambers, with a "disk type" system... I don't like the regular retaining screw system used on the current disk systems, & may set mine up with some type of propriotory clamp set up, in an effort to reduce the maintenance required...

I don't plan on serious work on an exhaust system, untill snow flies, but intend on running over to DIRTYWHITEBOY's neighborhood ( the closest dyno ), sometime this winter, to tune the disks...

anyone interested in this project ??? perhaps we can discuss it publicly on the forum, & have several systems fabricated, & coated at the same time, if anyone is interested...

 

Very good post newbeatle, you hit the nail on the head. Headers, EFI runners, heads, everything has proven what you said as horsepower vs torque. The stepped system you speak of, do these start with small diameter pipe then get bigger? Im interested in this project and tunable would be nice! short race, trail rides=torque. top end speed runs= horsepower. get the best of both worlds. I wonder if anyone has ever made a cutout for the exhuast like the old muscle cars used to do. Flip the handle and it was a dumped straight pipe. Keep us posted.

 

most / all of the comercially available "stepped" systems, match the size of pipe to the exhaust port, then step them up larger, in route to the silencer...

 

LOL, I guess i didnt give that question much thought before I asked it did I, sorry for the stupid question.[img]i/expressions/face-icon-small-blush.gif[/img]

 

lookin like I might make up my own pipes... if they are to be equal length, the silencers will end up staggered , or I could use different amount iof restrictor disks to simulate equal length pipes, as far as resistance... any more input ???

 

I'm interested in a dual exhaust setup for my 650 or should I say want dual exhaust setup.

Somebody put harley pipes on theirs to make duals and posted it, I believe he called them cherry bombs.

Even the aftermarket pipes I put on my old/sold Yamaha Virgo 1000 might work. I'm sure they were narrow enough and not that expensive to boot.

kawi makes a V Twin motorcycle, maybe their mufflers could be implemented easier.

Maybe a front end smashed up V Twin motorcycle exhaust could be had cheap for experimentation but I suppose they would be in most cases, too long. Being chrome might be a pain too I suppose.

keep us posted, I'm all ears anyway,

 

you would want to keep the pipes as similar i length as possiblei am working on a decent about equal length set-up that will have one can on each (right and left) side basically to make up the length difference i think i am going to have damn near loop the rear pipe around like a pig tail yet leave enough space in there for the header wrap...and to make the bends as smoth as possible i am probably going to mandrel bend only so much of the pig tail at once then weld the sections together and then have the pigtail section extrude honed to smooth it out (if possible)also, just for fun sake, what if you were to do one tube larger for more top end and one smaller for more lowend?

 

NB,

I am interested in the outcome of the project, but actually more interested in your used Big Gun. Want to dump them at a real low price to a needy Prairie? My 650 needs a system in a bad way.

Is there actually room for two silencers on our quads? I've thought about this in the past and it seems a bit cramped under there for two standard sized cans on the left side. Do you go the VForce way with a split system or the Aprilia Mille style & maybe fabricate your own smaller ones?

Can a bike like the Suzuki SV650 offer any inspiration for header length/cross-tube placement? Same displacement, but they tend to rev a bit more than our machines. Just a thought.

 

FAST... welcome to the forum... yes, I'll likely look over the similar displacement road bikes ... with the proper heat shielding, I think there is room for 2 full sized canisters, but I'll likely put together something smaller... my 1st thoughts, though, were to use an existing canister, & this may still be possible, by changing out the inlet end, for a single pipe, or using 2 canisters off of a V Force system, or a smaller silencer off of a similar 2 cycle system ??? I'm still open to design aspects of a dual system, & I'll likely set up 2-3 rough in system variants, to take to the dyno, to run against the base line that I'll run the same day with the Big Gun system...

Oh, I doubt you'd want my old Big Gun, anyway... she's been though more mud bog races than you can shake a stick at, & is now ceramic coated in Minnesota "brown" ceramic... ( it's pretty ugly right now )

 

NB,

I'd stay far away from 2-stroke pipes, as they are not nearly big enough for a 4-stroke exhaust pulse (500cc GP 2-strokes showed virtually no gains when silencer ports are open more than 1-inch--even at 200bhp, but 4-strokes of lesser HP certainly do!). How about an MV Augusta-style silencer? Small O.D., but still big I.D. with plenty of flow. Have you considered a system like Cobra offers for a shorty Harley-style slip-on? Cobra Harley Soft-tail Some of these look promising to me (namely the Softail 2" drag & the Lo-Boy Staggered)

If your BG system is dent-free and works well I'd still be interested, ceramud coating included![img]i/expressions/face-icon-small-happy.gif[/img]