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Discussion Starter #1
I have a 92 1100 with several mods to the engine, including 1216 pistons, cams, mild porting, 1 mm bigger valves in older gsxr head, accel coils, adjustable ignition advance set at +4, cam timing at 102i 106e, 38 rs mikuni flatslides,using airbox with k&n filter and 50mm velocity stacks, micron 4-2-1 full system pipe. My question is would a 4-1 pipe give it more top end horsepower? This bike has been on the dyno several times, torque curve is really flat, bike makes 150hp, 88lbs torque. The numbers seem low for all the mods, but it runs really well. I have friends with busas and 12's, I can out run them until we reach about 170ish. It will also out run stock gixxer 1000. I can't afford to buy a pipe to just test out my idea, so if anyone has any expierence with this please let me know.

sorry i'm so long winded
 

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I'm certainly no expert, but it's my understanding that all other things being equal, a 4-1 pipe will offer more peak HP than a 4-2-1 which offers a flatter torque curve. How *much* HP is another question, and I really think that if your goal is to increase your flat-out top-speed, you'd be better off to play around with the upper fairing and tailsection to improve the aerodynamics, and perhaps the gearing as well (are you poppin' the rev-limiter in 5th gear? if so, try to go taller, and if not, try to go shorter on your gearing til it just *barely* pops off the limiter in 5th on a flat, smooth run). At least, that's MHO ...I find it difficult to believe that you're gonna gain enough peak HP just from a header swap to make more MPH than improving aerodynamics and optimizing your gearing. I *know* that there's definitely a "point of diminishing returns" with the top-end thing... each additional MPH will cost twice as much as the one before after a certain point. ...like I said in the beginning though, I'm no expert.
 

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Discussion Starter #3
The gearing is 15 46 which is 2 teeth smaller out back, running 520 and aluminum rear. bodywork is stock except for paint and no rear fender and no signals. It will just barely top out at the rev limit, which is 172 on the dyno. Not really looking for all out top speed, just like having a fast bike. I've taken alot of wieght off of it, its 470 with gas.
 

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You are about topped out on HP for what you are working with. Like Bones said it is an old bike, I know I have a 92 1100, well sort of. 150 rwhp out of a 1216 is good power, again shed more weight, and work on the suspension, more power will come from a bigger motor or turbo...
-Karl
 

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Discussion Starter #5
Thanks for all the input, I have heard about bikes (especially bandits) like mine with similar mods getting 160hp or so. Just was thinking maybe the pipe was holding it back. Just can't afford all the stuff to really make it fast (like wheels, carbon body work, and tank). I thought about putting a six speed trany in it too, but I don't think the gears would hold up. I have the parts from a 750 but I don't want to tear it up. If any of you guys on here have a 1127 motor with serious mods it will break cranks (just a warning) I have two of them in my garage each in two pieces. Every year or two I take it out and check it for cracks. If you buy a used one beware of this.
 

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Discussion Starter #6
The dyno i'm using is pretty conservative, stock busas only make about 148hp and 92lb torque. The guy had an open house one day and 3 busas showed up. One had full pipe and power comander it made 151 and 94. Stock gixxer 1000's only make about 137-138 on it.

To answer a question above, I do run it on the street, and at the track as much as I can. I live in montana so we go to spokane on occation.

The motor has pretty high compression so I have to mix race gas to keep it from pinging. 25% race gas to 75% pump gas.
 

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Um...you have a fast bike. Are you running this thing on the street? I thought so. If 170mph is not enough excitement for you on the street, you may want to consider becoming a freelance astronaut.
In my opinion, unless a line width on a dyno chart gets you off, you wouldn't notice a difference regardless of what pipe you install. Sounds like your looking for much bigger gains anyway.
 

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The 4-1 gives more top end at the expense of the low. The 4-2-1 gives a more streetable Torque curve. A good compimise is the Yosh Duplex that used a balance tube to give midrange. You need to get into reality and realise that you are on a 14 year old bike. I have been gearing my bikes to top out at about 135mph. At my age this is fast enough on the street. The added benifet is the gearing gives me a much better launch than the new stuff. If you Switch to a lighter set of wheels (aftermarket or 94-95 750) and upgrade you suspension. You could start to out run those newer bikes in the corners because a Busa will always take you above 170 unless you go Turbo. At 470 you can still shave alot of weight. Just get out and "Enjoy the Ride!"
Bones
 

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gsxr1216, my bike is similar to yours except for the internal engine mods(my je 1216 kit will be installed this winter). i am running a hindle 4-2-1 and i have ran a yoshimura r&d 4-1. i can not see much difference in the two. the only way that you may see a difference in a exhaust swap is if you get a header with larger diameter tubes. the only header i know that has this is a murray. these headers are mostly used for drag racing. hope this helps-
 

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If you want more top end work on gearing and aero my old 86 750 would peg the speedo at 280km, never did know exactly how fast it was as the stock speedos are a bit optimistic on the the top end but it would still hit the rev limiter. But I had changed the bodywork to a zx11 main fairing which is very aerodynamic and used an 89rr solo tail with an undertray. Also dont reccomend those speeds without good suspension and tires, mine had gold valves front and rear along with 97 forks and a ton of setup. Also being a 750 you need a long road to get there.
 

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Discussion Starter #12
cide, thanks for the info, do you have any dyno graphs of the two? Did the 4-2-1 give you more midrange? I've been told micron is a pretty good pipe but I don't have proof of that.
 

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Discussion Starter #13
I know what you mean about the pipe situation, I wonder if bandit pipes will fit? I used to have an 89 750, it gained 10hp with yosh pipe that was 4-1. Of course before-hand it was stock exhaust. It had no low end or midrange though, it would hardly accelerate below 4 grand, then after 9 or 10 it took off.

thanks for the help
 

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gsxr1216......

this winter i would like to duplicate your exact engine combo......

Could u give me a approximate of what all the parts and work cost you?

Carbs i already know, just like 1216 kit....head work, cams...etc.......

Thanks......
 

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sorry gsxr1216, i have never dynoed them. i have only tested them by gut feeling. my hindle doesn't feel like it has anymore midrange than my yosh i had. i do know that your micron is a very good pipe. if you do some checking, you will see that there is not a lot of pipe selections for our oil cooled bikes!
 

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gsxr1216, i have also wondered about a bandit pipe. i think the only thing that would be different would be the mid pipe. does anyone else know about bandit pipes on gixxers?
 

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Guys ask the reverse of that question ("can I run a GSXR pipe on my Bandit?") every so often on the lists I read... sounds as though you may have to change oil pans and pickups to make it work; the B12, at least, has a centerstand and the GSXR headers aren't the right shape to fit the sump.
 

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Discussion Starter #18
Z1bigtom,

You can spend way more than you want to on these things but here goes.

Cams $400
hardwelded rockers $400
bigger valves $300
piston kit $475
top end oiling kit $255
retainers, springs, valves guides $400
coils and wires $110
carbs $700
pipe $550
extra clutch spring $12
instaling valves, valve guides, mild porting $1000
gasket set from ape $160
adjustable ign advance $90
head gasket from cometic $50
velocity stack for carbs $50
adjustable cam sprokets $100

most of this stuff is from ape

the bottom end of my motor is stock but you could spend money there too.

all prices are ballpark figures
 

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turn up lobe centers alittle, 110 on both, 1216 i did not long ago, mild porting, stock cams, 38mm cv of a 750, k&n filter, 4-2-1 i manufactuer myself, runs past 12000rpm or 190mph on dyno. (same dyno zx12 194) on the road, lofts front wheel in 3rd or 4th with alittle clutch, bottom end power is good lifts front at 3000rpm
 
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