Ducati.ms - The Ultimate Ducati Forum banner

21 - 40 of 54 Posts

·
Registered
Joined
·
175 Posts
problem with 2 into 1 exhaust systems is that although you do get a little better mid-range power your other areas suffer
Don't meant to hijack the thread, but could you expand on this? I'm just curious to hear because aren't those exhausts all different variations on 2-1 exhaust? I mean, with the crossover on the stock exhaust, isn't that 2-1-2, and the last bit is just for looks and sound, no? In the olden days, on inline 4, Yoshimura Cyclone (remember those?) had not only 4-1 (or 4-2-1, depending on the model), they also had cross pipes right off the manifolds, too. Wonder what the function of those are.
 

·
Registered
Joined
·
616 Posts
There are and have been over the years many variations on exhaust systems back in the early 70's Paul Dunstall designed a system for 750 Norton's it was a 2 into 1 into 2 it worked well and yes the Japanese builders have also dont the same type of thing I am a BMW Master Tech and most of my expertise in in BMW's mostly the older twins, -Now modern BMW's even have gone to a 2 into 1 system but alot of the newer models they have done this for noise & emissions so they can pass everything for the government. But for the older bikes--I race a 1972 BMW R75/5 the 2 into 2 systems work better and have higher end HP and for racing thats what I look for --top end HP. The 2 into 1 systems do give a little better midrange power but top end they suffer. BMW has also used exhaust balance cross over's since before WW2, they do not seem to effect power it just seems to balance the exhaust between sides-example -if you dont have both sides-carbs- balanced perfectly it smooths them out a bit. My race bike when I did the exhaust I made it without a balance pipe-mainly to make it easier to get the front timing cover off quickly without burning myself when the engine is hot. The 900SS again I am not an expert on these but I have seen pictures of the exhaust and it looks like it is basically a 2 into 2 -2 inlets & 2 outlets and the collector I think is basically 2 chambers even thou they connect more or less. I have seen pic's where people have modified the collector closing the chambers after removing the top and bottom plate then welding pieces in to close them off so its more of a 2 into 2. With the Ducati 900ss how much of a difference does this make --my o.p.o not enough to spent the time to do it. But it always depends on what you are looking for--is it a street bike or a race bike--If a race bike we all do things hoping to find just that tiny little advantage.
 

·
Registered
Joined
·
1,731 Posts
Discussion Starter #24
Don't worry about that, Rex knows everything!

He even knows what a floating rear brake is and what a rear brake does!!! Unlike "Most" of us........
I never ... ever .. said that any of US doesn't know what a rear brake is for. Not once .. .ever.

I thought you said I was on your ignore list? If not, you'd be a lot happier if you were to make that happen.

I don't know "everything". I freely admit that. If I did, I'd have no reason to ask questions around here. You just don't like it when someone other than you gets more attention than you do. Keep it up, your well deserved and well earned reputation for being thin skinned and one who loves to report others just continues to strengthen itself.

:wink2: ~Kisses~
 

·
Registered
Joined
·
800 Posts
The stock 900SS exhaust is a 2-2 system. The crossover section in the middle doesn't constrict the headers down to a single pipe, it allows the exhaust pulses from one cylinder to assist in scavenging the gasses from the other.
 

·
Premium Member
Joined
·
850 Posts
So much speculation and so little actual 900 SS data/experience in this thread. I'd really like to hear about actual, recent data/experience with different exhausts with this motor.

Last winter, I did many dyno runs with 3 different exhausts on my FE. The exhausts tested were: an OEM header with slip-ons, a full Silmoto "spaghetti" system with Silmoto silencers, and multiple iterations of a custom 2-1 system. With the 2-1 system, I tested different primary lengths.

My motor is fully built: 944 Pistals, headwork w/reshaped ports and larger valves, FCRs, etc. The motor does 93hp / 71 tq.

There are many, many variables when evaluating exhausts. I'm far from an expert when it comes to this. In fact, I'd characterize my knowledge as very rudimentary. That said, here's my summary: my experience was that all of the exhausts provided roughly the same hp after tuning the carbs to each exhaust (another issue completely!). The primary differences were in the tq curve. The 2-1 needed long primarys of close to equal length in order to make similar tq, over a similar curve v. the OEM/slip-on and Silmoto system. The OEM/slip-on system is very, very good! My experience suggests that motors producing less than 95 hp / 70 tq will see little performance benefit from a full system.

I believe that other than pure performance, there are other benefits to be considered. The OEM/slip-on system is really heavy. The full Silmoto system and my custom Ti 2-1 system drop 10-15 lbs. Both systems also provide a lot more ground clearance when cornering. And the 2-1 system provides a lot more heel clearance for my size 12 boots. Some will also like the aesthetics of these systems.

I'd be very interested to read about other' actual experience with different systems.
 

·
Registered
Joined
·
6,109 Posts
I’m surprised that the Silmoto wasn’t significantly better than a stock 2-1-2 with slip ons. The x pipe on the stocker seems quite restrictive, just looking at the design and size of the pipes. I have a full Staintune and the crossover area of the pipe is where they changed the design for better flow. Stock mufflers are really heavy though.
 

·
Registered
Joined
·
1,701 Posts
I’m surprised that the Silmoto wasn’t significantly better than a stock 2-1-2 with slip ons. The x pipe on the stocker seems quite restrictive, just looking at the design and size of the pipes. I have a full Staintune and the crossover area of the pipe is where they changed the design for better flow. Stock mufflers are really heavy though.
i've tested oem (st4s 45mm) and full fabricated cross over headers on an 888 and it would appear to have made no difference at all. i'd say that stamped cross over is quite efficient.
 

·
Registered
Joined
·
1,701 Posts
So much speculation and so little actual 900 SS data/experience in this thread. I'd really like to hear about actual, recent data/experience with different exhausts with this motor.

Last winter, I did many dyno runs with 3 different exhausts on my FE. The exhausts tested were: an OEM header with slip-ons, a full Silmoto "spaghetti" system with Silmoto silencers, and multiple iterations of a custom 2-1 system. With the 2-1 system, I tested different primary lengths.

My motor is fully built: 944 Pistals, headwork w/reshaped ports and larger valves, FCRs, etc. The motor does 93hp / 71 tq.

There are many, many variables when evaluating exhausts. I'm far from an expert when it comes to this. In fact, I'd characterize my knowledge as very rudimentary. That said, here's my summary: my experience was that all of the exhausts provided roughly the same hp after tuning the carbs to each exhaust (another issue completely!). The primary differences were in the tq curve. The 2-1 needed long primarys of close to equal length in order to make similar tq, over a similar curve v. the OEM/slip-on and Silmoto system. The OEM/slip-on system is very, very good! My experience suggests that motors producing less than 95 hp / 70 tq will see little performance benefit from a full system.

I believe that other than pure performance, there are other benefits to be considered. The OEM/slip-on system is really heavy. The full Silmoto system and my custom Ti 2-1 system drop 10-15 lbs. Both systems also provide a lot more ground clearance when cornering. And the 2-1 system provides a lot more heel clearance for my size 12 boots. Some will also like the aesthetics of these systems.

I'd be very interested to read about other' actual experience with different systems.
can you start a new thread titled "900ss 2-2, silmotor and 2-1 exhaust variations with dyno charts" and publish it all there. if you don't publish stuff like this how are we supposed to know? no one does that sort of testing, which is why there is so much speculation here.
 

·
Registered
Joined
·
4,668 Posts
Bikeboy has done a lot of dyno work on 2v bikes and posted it on his site.

It's a lot of good information if you have time to go through it all.

BikeBoy.org
.
 

·
Registered
Joined
·
1,731 Posts
Discussion Starter #31 (Edited)
(shortened to comply with the complaints about my long posts ... cuz y'know ... it's so hard ... life is hard ... reading is so hard....)

... please continue with your side discussions and such. There's a good chance some new information will come from those discussions, so keep on keepin' on!!!!!
 

·
Premium Member
Joined
·
1,003 Posts
Hi Guys,
I've done a ton of Dyno testing on this very subject and built many different configurations and tested just about all the systems for the 900ss engines. It was a few years ago, so Ill dig up the plots and post them soon.

Simply put, just like history has shown the Spaghetti system makes the most top end power giving up midrange to the 2:1. For race and RPM range over 6k I would want the Spaghetti Design. For street and better seat of the pants feel I would want the 2:1. Believe it or not since these motors fire at 270 degrees, a classic merge collector does not provide good scavenging and can hurt performance. I got the best of both worlds with proper length open pipes no collector but a crossover at an optimum position so they can talk but not scavenge. But trust me nobody wants to hear that noise. All of this testing was on a built motor similar to 4Rings build. So a stock motor may have a different outcome, as cam timing Compression ratio and exhaust duration plays an important role, especially with the ST2 cams which in my opinion have too much exhaust duration. Ill post some plots soon.
 

·
Registered
Joined
·
616 Posts
If you have a copy of LT Snyders book--Ducati Desmodue/Desmotre Maintenance & Modification guide --in the Other modifications swction he has a picture of an exhaust that he had made for his 900SS, it's a dual setup on the left side of the bike. It was built by BCD fabrication but they are out of business but he says Doug Cook is still buildng these--but this copy I have is old so you never know. maybe this picture will be clear enough. the 2nd pic has all the info thats in the book
 

Attachments

·
Registered
Joined
·
616 Posts
From what I have always known and seen Stingers is a term that is used for 2 stroke bikes with chambers and the stingers are a type of tip coming out of the chambers.
 

·
Registered
Joined
·
1,731 Posts
Discussion Starter #36
Side-by-side pipes are known as shotgun exhausts. Why do you call them stingers?
Throwback to 2 stroke racing days. It's just a word. You call them shotguns (which are not just side by sides, they are straight pipes) ... I call them stingers.
 

·
Registered
Joined
·
1,731 Posts
Discussion Starter #37
From what I have always known and seen Stingers is a term that is used for 2 stroke bikes with chambers and the stingers are a type of tip coming out of the chambers.
Careful! You're up to five posts today and it's not even halfway over.

>:)
 

·
Registered
Joined
·
616 Posts
But I am going to be gone for the next 10 days lol
 

·
Registered
Joined
·
541 Posts
if you're ok with a Dirtbag Challenge / Steam Punk aesthetic, got a bit of spare time ..and you seem to have some spare time on your hands.. ':D it could be fun.

Go to Summit Racing, etc, to buy the various thin wall stainless steel angle/bend fittings and some straight pipe sections, along with a set of the stock header pipes. build it up with starting from the header side, and tack weld as you go to hold the growing assemblage together, use a
so you can slip pieces together - rent from AutoZone. or make runs to the muffler shop to get the pieces expanded in their rig. Piece it together. Once it's to your liking, take it to the local exhaust/muffler shop artist [look at his examples fo work firsthand] and haggle to get it fully welded up & ground smooth. I found a Michaelangelo once in the Berkeley flats who did antique Alfa & Ferrari fab work. I digress..

Summit:
https://www.summitracing.com/search/part-type/exhaust-pipe-adapters-and-reducers
 

·
Registered
Joined
·
1,731 Posts
Discussion Starter #40
My shop;

700 sq/ft ... 300 amp TIG ... 200 amp MIG ... 2 horsepower mill ... 2 horsepower lathe ... 3 drill presses ... Oxy/Acetylene rig fully outfitted with heating, cutting, welding, brazing gear. 25 ton hydraulic press ... 5 ton arbor press ... 1 ton arbor press ... manual tube bender ... three solid steel welding benches ... all steel and cement welding shed ... more power tools and hand tools than I can list without pissing off the ones that complain about how long my posts are.

DIY my own? Maybe. Depends.

.
 

Attachments

21 - 40 of 54 Posts
Top