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Discussion Starter · #1 ·
I just got my Suzuki Service Manual on Thursday. So I'm buzzing thru it and wanted to share what I came up with regarding the K5's top speed.

Speed = (13,500 rpm x 76 in. rear tire circumference x 17 front sprocket) ÷ (1.553 primary gear ratio x 1.269 sixth gear ratio x 42 rear sprocket x 1056)

17442000 ÷ 87407.014 = 199.55 mph (321.15 kph).
 

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very cool! so what would that be indicated? 225 mph or so?
 

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Discussion Starter · #3 ·
very cool! so what would that be indicated? 225 mph or so?
I suppose so. Lets say with a 10% error would put it at about 220 mph indicated. Not sure if the stock horsepower could do it. The word is you need over 200 hp to break 200 mph so it's interesting that Suzuki designed the drive to go that fast, perhaps they had the superbikes in mind.
 

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ok, you math wizzards freak me out.....
 

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Math not required........ the bke won't go ovwer 186 mph. Hell it won't even display over 186. You can get some idea by dyno runs, my stock 03 only did 178 (183 with JSD instaled). Would guess that current top speed is 183 or so, guess I need to put one on the dyno just for grins.

The one thing that you are missing is the CD. The wind is the single largest thing to overcome. This is why the Busa, is still faster on the top end over the 1k.
 

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Discussion Starter · #9 ·
you need the hp to get you over 200 no way it will break 200 stock...

Now that I think about it ...
is right...


If I recall back in '99 the Busa was close to 200 mph stock "without 200 hp" it was 198 mph for an average sized guy I think. Stock Busa horsepower is about the same maybe even less than the K5 is now, except for torque. The aerodynamic coefficient is better on the Busa I suppose but who has even tested it yet with the K5 numbers??? Maybe Suzuki knows from it's own R&D. The K5 has definitely improved on the aerodynamics coefficient, it's 4 or 5% more efficient over the K4. I don't think the K5 is too far away from 200 mph if the engine and electronics was tuned correctly for optimum torque and horsepower. Would you really need 200 hp? I don't think so. As Adam said the Supestock bikes are hitting close to 200 mph on limited sized circuits. The Busa with 170 some odd HP at the crank can get to 200 mph.

This speed thing is a weird deal so I don't know what to think when it comes to any given set of circumstances for a particular vehicle attempting top speed runs. To me it would seem if a light weight guy fixed the K5 up right without any restrictions or any major engine mods he might have a chance to hit the factory spec gear ratio for speed. The only way to know would be to take it out to the desert or salt flats and run it in the best conditions. I think that would be a lot of fun. Anybody want to plan a trip or something to really get the numbers on the new bike?. There must be a reason why Suzuki gave us enough gear on the K5.


Can anyone get the K4 numbers to see the estimated top speed, I am curious?
 

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Discussion Starter · #10 ·
Math not required........ the bke won't go ovwer 186 mph. Hell it won't even display over 186. You can get some idea by dyno runs, my stock 03 only did 178 (183 with JSD instaled). Would guess that current top speed is 183 or so, guess I need to put one on the dyno just for grins.

The one thing that you are missing is the CD. The wind is the single largest thing to overcome. This is why the Busa, is still faster on the top end over the 1k.
Yep I know we are in restricted mode but that can be fixed. I simply don't trust the numbers from the dyno especially with top speed. Your right about including the Coefficient Drag (CD), that would knock off on the actual top speed. I suppose you could tune the engine, drop the rear sprocket and /or increase the front and tune the engine, might get you a chance at 200 mph?
It's fun to think about though.
 

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Nice bikes and cool your girl rides.

My girl is to fat to ride. If she wanted to ride she would need to get a big Harley or a 3 wheel trik.

On the postive side if we ever got stranded in the winter I could live under one the folds on her gut and stay nice and warm until help arrives.
 

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Can anyone get the K4 numbers to see the estimated top speed, I am curious?
I think JeffW posted up this Excel spreadsheet about a year ago. I grabbed it and used it to check the accuracy of my Speedohealer, which is about dead on the money up top - I've only managed to redline 5th and my K3's speedo showed 178. If I could've grabbed 6th, she probably had only a few more mph to top out. But, I converted the page to jpeg showing stock gearing and tire size. Looks like the the earlier gixxers had about as much gear on top - notice the 197.8 mph gearing in sixth.

BTW The speadsheet is cool - just plug in changes for gearing or tire size, even tranny ratios, and the sheet recalculates on the fly.


Edit: SHIT - sorry about the extra whitespace in pic...

 

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mine does more than 89 in 1st gear so you sure these figs are right? or are they maybe true speed vs speed on the spedometer?
 

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Discussion Starter · #16 ·
mine does more than 89 in 1st gear so you sure these figs are right? or are they maybe true speed vs speed on the spedometer?
The numbers in that chart is for the K3 or K4. And yes those would be actual speed numbers. The speed formula is for actual distance over time traveled and doesn't account for coefficient drag or any speedometer errors. I also should add that the advertised maximum rpm limit is usually over the actual rev limit set by the factory.

Suzuki rpm limit specification for the K5 is advertised at 13,500 but it's actually 200 rpm less at 13,300 according to the service manual, regarding the ignition and/or fuel cut-off programmed into the stock ECU. They always create a buffer from the advertised maximum rpm. I assume they want to maintain a safety margin.

Indicated speed is also not accurate on the GSXR.
 

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Discussion Starter · #17 ·
Can anyone get the K4 numbers to see the estimated top speed, I am curious?
I think JeffW posted up this Excel spreadsheet about a year ago. I grabbed it and used it to check the accuracy of my Speedohealer, which is about dead on the money up top - I've only managed to redline 5th and my K3's speedo showed 178. If I could've grabbed 6th, she probably had only a few more mph to top out. But, I converted the page to jpeg showing stock gearing and tire size. Looks like the the earlier gixxers had about as much gear on top - notice the 197.8 mph gearing in sixth.

BTW The speadsheet is cool - just plug in changes for gearing or tire size, even tranny ratios, and the sheet recalculates on the fly.
Very nice chart, thanks for the info.
 

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Do you know what the Primary Reduction Input/Output gears are? The closest I could get to the purported 1.553 was to put a 52/81 combo in for the Primary Reduction.

Using 1.557 Primary Reduction, and the 17 front and 42 rear sprockets, and the 76 inch Measured Rolling Circumference, I came up with a figure of a 6th gear max (at 10,700rpms), of 191.8 mph. If you're willing to dip into the red, at 10,800 you should get it to 193.6mph (allowing for a full tuck and no head wind or very neglible cross wind. I think realistic top speed without gear change is pretty close to 193mph.

I have a 2000 Busa. It's Primary Gear Reduction is 1.59615 (52/83). Coupled with the 17/40 stock Secondary Reduction and all things being equal, its top speed in 6th at rev limiter should be 199.1 mph. Dip into the red at 10,800 and as long as the winds are not limiting either against or cross-wise and I should be going about 200.9 mph. I've had a 16 front on the past year and can only go about 194 if I'm willing to dip into about 12,000 (which I've done about 3 or 4 times this summer). However, I'm thinking of putting my stock back on or even putting an 18 on the front to make sure I can go over 200mph.

BTW: You can have 100hp and hit 200mph if you have the bike geared right. The gears determine top speed, horsepower determines how quickly you reach each gears top speed. I have about 170-172 at the rear wheel right now (race pipe, PC3usb, TRE, airbox mod, K&N, pair valve mod). Still, I want to trade my bike in and get a GSXR1000 so the guys in town stop walking away from me when cloverleafing. I'm scraping pegs and there's a couple of guys that still get away from me (shorter wheelbase, I know).
 
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