2-1 exhaust rejet?
 

Hi i have a 2-1 hindle carbon exhaust on my hawk and i have a huge flat spot between 6-8k at wot where the bike spotters and then goes like stink at 8k+ rpm. I am nit sure if it is a stock header modified for a single pipe or a hindle one. However at the mid pipe junction there is no fin in the header that splits. I also have a bmc air filter in a non modofied airbox

Anyone had success with a good jetting receipe for a 2-1 system? I searched but could not find the information. Thanks

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Header
 

Looks as if we both have the same 2 into 1.


I have looked end to end on my header and there are no markings what so ever.


No Honda numbers, no aftermarket markings, nothing.


If you ever figure out who produced this set up let me know, thanks!


SIRR1

to me it looks like a stocker moded into a 2 into 1. maybe there was a company who used the stock system as a startng point?

either way everything ive read always comes back to 2-1 systems really loosing out in terms of performance. its more of a looks things. theres a reason Honda put 2 pipes on the VTR, as well as almost every other v twin bike out there, Ducs, aprilias, etc...

if it was a good way to go than everyone would do it as it would drop some weight, and loose some uncentralized mass.

that being said you can obviously find the optimum jetting for your pipes. might not be as good in terms of power numbers as a 2-2 set up but you should be able to have it running without the "flat spot" your describing

EDIT:
or i could have read lloydies post before i put my foot in my mouth.... oops. it really suprised me to see 3hp and 2 ftlbs gained. although its the fine tuning that makes all the difference. still, most 2-1 set ups ive seen lost all around. go figure.

My 2-1 is a standard vtr headers modded for a 2-1 very simple to do if you look at that link I posted up it shows how I did it .
You do loose a little in the bottom and mid range but gain a little up top .
It be good for racing but not the road as you spend most of the time in the mid range and that's why I've gone back to a 2-1-2 standard headers

When i converted it to naked, i tucked the wiring under the tank/airbox. The wiring is in the way of the snorkle that sucks the air in the airbox. Which is probably a part of the problem. The bike seems to be running super rich, i was driving tonight and on the highway i pulled the choke to see what it would do and it just felt on its face, almost turning off.

I might take all the wiring out just to see what it does

I did the same thing for my conversion. Yes, it makes a huge difference. Mine acted like if had a limiter at 7k rpm before I cleared all the wires. Make sure you keep the big plastic heat shield in there too. It also stabilizes the air pocket god the intake.

Edit: also, the choke test is pulling the choke only a little bit. If you pull it all the way out at highway speeds it will make your bike will go all kinds of wonky.

For those of us that do track, this is interesting. Good chunk of weight to be saved with more HP.

It debunks the restriction in the stock pipe theory.

Thats exactly what mine does. Where did you put all the wiring then?

And just like that, even if we loose 2-3hp with a 2-1 system, isnt the 20 pounds saving an advantage vs the 2-3hp even on performance?

Sure, if it's that simple. I'm all for tinkering, just remember these things:

lloydievtr didn't just chop the stock exhaust. He re-sized the connector and made his own mid pipe larger to handle more volume. But that aside:

Just 2-3hp may not tell enough story. You should consider the whole dyno curve and what the bike is used for. Two horsepower at 8k rpm, but ten horsepower loss and a flat spot at 5krpm may not be a good tradeoff. Showbike? Just needs to run to the bike show and back? No worries. Daily driver or track bike? Different requirements. It's all about what you need...

I ended up hiding some wires under the carbs, most behind the headlight and some in the tail. For awhile it was pretty sloppy, but I tore the whole thing apart a year ago and ran everything better.

I wouldn't put a lot of trust in those dyno charts and maybe the fact that he changed back to a 2-1-2 system might be a better thing to judge by.

My questions on the dyno run are first was the restriction at the head cleaned up on the first run with the stock system?

Then I look at the A\F ratios. They are way off but a bit leaner on the run with the 2-1. Is that where the extra 2 HP came from? The red line is so rich it pegs the meter, so I would have to say it has a rich misfire at that point.

So IMHO it comes down to the simple fact that if you don't mind peaky power and are just looking for top end HP a 2-1 will work well for you but then why are you riding a twin?

If you want a big fat torque curve and smooth power delivery a 2-1-2 system will give the best results..... and I bet my system is lighter than most 2-1 set ups, so win -win for me.....lol ;)

Without stirring this thing too much, since opinions are like belly buttons and other body
cavities(everyone has their own). The primary pipes on the hawk are slightly under 2 inch ( almost 59mm) and then merge into a pipe of the same diameter, the primaries are not in anyway close to equal length, the lower pretty tightly curved section of the rear tube is not a mandrel bent but rather stamped out and welded together fabricated piece. The folks at Honda were not aiming at a race pipe, but rather a expedient way of connecting the exhaust port to the muffler within the constraints of the real estate they had to work with. If the factory Superhawk pipe is compared to a factory racer pipe. Well they just Don't compare! We have a production bike. Granted a Very fun, smooth riding, good handling (within limitations), and within its' class quite torquey and powerful bike.

So. If optimum power is the goal then we need to get the engineers to go back and do some design work disregarding production cost and time in redevelopment and bring us a new set of pipes. Do you think that's going to happen?

Or we can take what we have and make the best of it, have fun tinkering. Modify it to our individual taste and riding and ENJOY!

Dyno tests are really great, but the variables, unless numerous back to back pulls are made, are almost endless. So what is haggling over some gain or lack of it really accomplish? Bragging rights? I know more than you do? My Hawk is badder than your Hawk?

It is a well established fact that volumes of horsepower are generated by volumes of$$$$$$$$. Other wise Mr.Ditchfield (a true craftsman)wouldn't be as successful as he is.

Bottom line if it looks good to you, it feels good on the seat of the pants dyno. It's your scooter! Go for it!



The Dragons Tail is in my backyard

Agree with what you are saying, but I think the primaries - "headers" are indeed equal length. Look at the curve in the back of the rear header. I think if you measure it you will find that the length is the same as the front (just trying to make sure all the information is correct here).

Also, I agree with the idea that if you like it, then go for it b/c the best dyno is a placebo butt dyno... BUT you only know the best that you ride, so if you're romping around on an 85hp Superhawk with a flat spot and come saying it runs "fine" with one pipe, I would say try a properly tuned one with 110 hp and no flat spot before you make that assertion.

If Honda, or any company for that matter, could gain 5hp from a simple mod that you can do at home you can bet they would look into it... There are certainly many places where budget and production capabilities limit what the will do, but if they could reasonably use one exhaust can (saving cost, weight, complexity, etc) I bet they would. I guess what I'm saying is doing it because you want to is enough justification in itself, so there's no reason to pretend there aren't sacrifices being made and hiding where those sacrifices may be.

Not sure about your post but I will say that the stock pipe is very good.

People with reps as good as Mr Ditchfield have said as much. Then again it is just an opinion.

As for the pipe design. The 180 degree turn makes the path "seem" longer to the gas flow so even though they are physically different lengths they "appear" the same to the gas flowing through them. Standard exhaust system design theory.

Yep...got one on my bike, though they are tough to find anymore. There were 3 good ones IMHO and mine makes more power everywhere than stock and the whole system weighs less than 1 stock muffler.

The whole dyno attitude thing is kind of odd.... that is the only way to really tune a bike.

The seat of the pants dyno, while ok can be very deceiving. I have seen more bikes that the owner has claimed were running great and making a big power hit..... when what was really happening was the power hit was the bike pulling out of the hole in the power-band that they had made.

As someone who has seen my fair share of carbs, I would always take dyno time to get them dialed if it was available.

I wouldn't even bother with the new FI boxes with out it.

So while I agree with your point of its your bike and just do what you want. But don't agree that dyno charts are just some sort of bragging right. Then again it's just an opinion.

Left side muffler was damaged when i bought the bike and this system was in the classified on here at the time i was looking for a replacement system. I bought it for a good price and will try to run it for this summer. It sounds badass, its super light and i like the looks of it.

I ride only on the streets, i am an aggressive rider, but not out of control aggressive neither. I like to wheelie, take corners fast and enjoy a ride. Thats about it. I don't showoff, i don't wait for people to ride, i just ride because i like to ride. I also like to modify stuff. Not sure why, but i have a problem with stock vehicles..

Hey guys! I'm not throwing cold water on the lighter single sided exhaust idea in anyway! I LIKE IT! The weight savings, the appearance even (other than aesthetics) what does the
second can do! After the choke point where the front and rear pipes come together the right side is mostly unrestricted. The left side midpipe on some aftermarket have a divit in them for chain clearance, but they are larger internally than the merge point of the primaries.

Dyno, specifically chassis dynos are a useful tool with limitations. The guys that do the engine builds for the race teams have do the direct connection thing for nitpicky infentessimal wring out the last drop of Hp/Ftlbs of power that can be gotten from a given setup. I completely understand that every neighborhood bike shop doesn't have a 1/4 Mill. just laying around for a rig like that.So you get a pretty good approximation of with what they do have to at there disposal. And if they register and increase in performance that is Outstanding! If not, back to the shop for another cold one and some more brainstorming. It's fun, it's how improvements are sometimes discovered.

I maybe wrong but I believe the number was 2-3hp instead of 5hp gained. Which is significant and not to be disregarded. As far as the manufacturers getting in a horse power war, a gentlemans agreement to give them enough performance to keep them interested unless they are willing to show that they are Really$$$$$$ interested. That occurance was around the 2000 mark (ie. Blackbird vs Bushas speed limitations from the factory).

But hey guys as I said first thing. I'm not here to try and convince anybody of anything. "A man convinced against his will is of the same opinion still". Just pointing to some obvious prominent short comings in "our" hawks pipes. And those that agree we can stand back and say, "yup there it is, what can we do about it? What about...".

By the way my "seat of the pants" dyno started operating in the mid-sixties, so it's not like, though being relatively new to this forum, I don't have couple of pulls on bike with some performance.

Back to the pics the the very smooth single sided exhaust. That is a really clean job! Well thought out and executed. My compliments!!

By the way Hawk those of us that ride carbed bikes can only try to balance the trade offs that occur throughout the operating range of the engine. Modern fuel injection give a Much! more exact method of metering the fuel/air ratio going into the engine at any RPM, thus allowing the smooth operation whether idling or under heavy load. A dyno is a mandatory tool to correctly tweek them in. Even the supposed learning systems have to be helped along and then brought an precise state of tune. No problem with a dyno and a laptop! Carbs are not rocket science either if you have a dyno available and can recognize what you are shown on the graph. I haven't gone back to reread, but the observation on the F/A ratio on the top end of the dyno run was pretty good. Good eye!



The Dragons Tail is in my backyard