Topic: 2-1 vs 2-2 on a 750 v-twin

[wannabridin]

hey guys.  i'm about to start building my own exhaust for my honda 750 v-twin.  i'm thinking of going with 1.5" individual pipes w/ a 2-1 collector and a 2" supertrapp 17" long muffler.  EVENTUALLY this bike will have some good motor work done (high comp pistons, cams, headwork, etc), so probably 65-70 hp when that's done down the road. 

do you think i'll get the most performance benefits using the 2-1 system?  i like the looks for a flat tracker style build, and running 2-1 "saves" me from having to have fully equal length pipes, as the collector should help with scavenging.  please let me know your thoughts/opinions!  thanks.

[lucky]

hey guys.  i'm about to start building my own exhaust for my honda 750 v-twin.  i'm thinking of going with 1.5" individual pipes w/ a 2-1 collector and a 2" supertrapp 17" long muffler.  EVENTUALLY this bike will have some good motor work done (high comp pistons, cams, headwork, etc), so probably 65-70 hp when that's done down the road. 

do you think i'll get the most performance benefits using the 2-1 system?  i like the looks for a flat tracker style build, and running 2-1 "saves" me from having to have fully equal length pipes, as the collector should help with scavenging.  please let me know your thoughts/opinions!  thanks.

Most all of the v twins that win races have two separate exhausts.
Think of the HD XR750, they won the most races in every type of racing.

In drag racing most all cars and motorcycles have 4 separate exhausts for the majority of the racers.

There are always exceptions and it is a long discussion.
Street,drag racing, road racing etc.,.

[wannabridin]

Well just looking at some professional race bike doesn't really help my case.  I know the basics of exhaust building, and if you go 2-2, you need equal length pipes, to match backpressure and keep tuning equal.  Some recommend 2-1-2 using a crossover pipe and 2 mufflers, but I've seen plenty of articles in magazines saying that 2-1 systems on harleys and other bikes helps a lot more than 2-2's...  2-1's make more mid range power and torque, and 2-2's make more high rpm power.  This bike will be ridden most in mid-range, so I feel 2-1's would be good.

Anymore advice or theory knowledge?

[Steve_K]

I had a Hindle 2 into 1 on my SV650, a SuperTrapp 2 into 1 on a Hawk GT and Yoshi canisters on my (2-2) SV1000.  The SV650 and the HawkGT came stock with 2 into 1's.  That said a 2 into 1 may need a larger canister. Early Apprila twins had 2 into 1,too.
I suppose, you should do what looks right.  Max performance is not your goal, I think, make look right to your design.
Steve

[wannabridin]

Max performance is the end goal, hence the supertrapp, being tubbable and all.

I want to use the 1.5" pipe for low end torque, and because the kits are for and XS650 and are $50+ cheaper than the 2.0" kits... 

What about sizing?  Anyone think 1.5" will be too small??

[Retro Rocket]

Most all of the v twins that win races have two separate exhausts.
Think of the HD XR750, they won the most races in every type of racing.

Where do you get your information dude..?     It's success was in AMA racing  and would have been well and truly flogged in any other form of racing, it only ran in "C" class.  At its peak it only produced around 100HP, there wasn't much Harley about it either, it used Italian forks, Japanese carbs and British shocks.  Other bikes that threatened it in racing were banned from competing against it like the TZ750 bike of King Kenny Roberts . The XRTT road racer only won a few road races and it won its last race a long long time ago.....  To call it the winningest bike in "every type of racing" is totally incorrect.....

[Danno]

if it were me I would use the larger pipes and create a crossover between both sides and a single hi flow muffler it is the easiest to tune and gives race like performance and after all I believe you said this was going to be a street bike

I am all for the best flow possible but when it comes to tuning I want it to be consistent so I always bank my bikes together in at least 2 cylinders for tuning and sometimes use an equalizer pipe to join the banks together on seriously hi flow applications to protect the valves and aid in tuning

[wannabridin]

good idea on that.  would an "h-pipe" suffice, just a piece of tube between the two?

i'm going to call a guy i know who does custom motorcycle work, and see if he can make me some bends out of pipe.  but i still think 1.5" pipe will be fine, as the stock exhaust ports are 1.5" in diameter.  if i could make the head to pipe transition better (stock there's a decrease in diameter) and keep it a consistent 1.5" until the connector, then i think i'd have quite a good setup.  and of course, an equalizer pipe is a great idea, thanks.

[Danno]

yes bud as long as it had enough diameter to carry the exhaust from both banks in your case 1.5" will probably work

[wannabridin]

found the exhaust i'm going to somewhat model mine after, i think it's AWESOME!  totally simple yet functional!