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final drive ratios 9 years 6 months ago #4481

  • jwb47
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Is their a supplier that has a different gear ratio for the final drive?
a run a turbo and it winds up to 10,000 in fifth way to quick. and with tires that is only 160 mph. gets their way too quick. bought bike new in 79 and been to hell and back with it. Just want to go faster.

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final drive ratios 9 years 6 months ago #4485

  • Toddh
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Years ago, I turbo'd a KZ1000 shaft. That bike had final drive issues ratio wise like you mention above for the 1300.

I was able to lower the ratio to better match the pwr output of that 1105 turbo motor by going to the final drive on the KZ1100.

Being that the 1300 had the most pwr and torque out of the entire Kawasaki lineup that year, I doubt if we could find any separate Ring and Pinion gear set, unless a lot of research was done into finding a separate supplier for said gear-sets.

I'm not saying it is impossible, just don't recall any lower ratio's that go in that direction with more pwr and torque of a turbo motor.

If anyone else has had experience with this, please chime in.

Regards.

T.
KZ1300 A-4 4TH 1300 IN 30 YEARS
KZ1000 D-3/ Z1R
ZX900 GPZ A-3
KZ750 E-1
K1200GT
CB750F 1978

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final drive ratios 9 years 4 months ago #5395

  • trikebldr
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Ah, you guys are talking about what Lucasind and I have been working on lately! He was complaining that his ZN tachs at about 4000rpm at 70mph. He doesn't like that! OK, so I too have found myself stabbing for a sixth gear around 70-80mph. These cruisers just have a lot of torque. But, NOBODY makes, or ever will make, a different gear set ratio for these bikes since there were only about 4500 of them made, a lot of them are now gone and most owners don't care about the engine speed at highway speeds anyway! They aren't like cars where you can find dozens of different ratios for any rear end.

What to do?

Well, for one thing, the KZ's final drive has a ratio of 3.18-to-1. The ZN's final drive has a 3.40-to-1 ratio. So, that leads one to ask if the KZ drive would fit on the ZN. NO! At least not without a lot of cutting, aligning, welding and a little bit of adapter fabrication! A lot of work for such a small change in engine speed.

So, with a bit more research I found out that the Gold Wing 1200/1500 final drive has a 2.833 ratio. That would make the ZN's engine run at 3333rpm rather than at 4000rpm at 70mph. But, can it be done? I think so.

I bought a used swing arm and driveshaft from a ZN1300 so I wouldn't butcher my original ones on my bike, as well as making it easier to remove intact, and a final drive, driveshaft, rear wheel and swingarm from an '84 GW 1200. Grafting the final drive unit to the ZN's swingarm will be a piece of cake. A small adapter to attach the lower end of the ZN's right shock to the Honda drive case will need to be made. A GW 1200/1500wheel will have to be used since a wheel's interface to the final drive output is unique to almost each bike make and model. No big deal since it is a 16" wheel just like the ZN's. To mate the GW's drive box to the ZN's swingarm I will cut off the right end of the GW's swingarm and graft it onto the right side of the ZN's swingarm. The bolt flanges are quite different and not the same distance from the swingarm's pivot. This is where all of the careful fitting and alignment happens to place the wheel exactly where the ZN's wheel was. But, it's not that hard using a jig. The left arm of the swingarm has the axle boss to locate the wheel and drive unit. There's more to this, but it gets complicated.

The hardest part is grafting the two driveshafts together. The front part of the ZN's shaft has to be used to mate up to the ZN's tranny output flange, and the rear part of the GW's shaft has to be used to mate up to the GW's final drive input coupling. The difficult part will be getting the metallurgy restored after the welding and balancing is done. I have a local shop that makes custom driveshafts and can do the heat-treatment part of the job. Still, this will NOT be as strong as a stock shaft since they are forged units from the factory. I will be using a welded-on sleeve over the welded/ground area to help beef it up. I still don't believe it will repeatedly stand up to doing burnouts and side-slips of the clutch. But, on a ZN, this shouldn't be a problem since these heavy bikes weren't made for that kind of abuse anyway. On a KZ1300, that's a different story. I have no reservations about full throttle AFTER the clutch is engaged, in any gear, but just not for drag racing.

Since your KZ's start with a 3.18 ratio, they wouldn't gain as much advantage as the ZN's do by going to the GW's 2.833 drive, but it's the only game in town, as they say! Bigger tires are limited, but could also add to the advantage, IF, IF, IF they meet the speed requirements you are looking for. Also, by calculation, if you are now clocking 160mph on your KZ, then this new ratio would only increase you to 179.59mph if your engine could pull the same rpm.

I now have all of my used parts off of eBay to do this build and will have it ready for testing next spring. As Lucasind says, it will be a Hondasaki drive. Lucasind has done a lot of research into finding new gears, but has turned up nothing. I would have bet on that outcome! So, this is what I have come up with for his, and my bikes. Will let you know how it turns out! Not so sure I would want to try it on a 180mph bike, though!

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final drive ratios 9 years 4 months ago #5398

  • RickG
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Have you checked out the early K series BMW they have a big range of ratios, 2.52, 2.62, 2.75, 2.81, 2.93 3.0 3.09 and 3.20 and some even higher ratios if you go to the R series.
Live your life so that the Westbro Baptist Church will want to picket your funeral
Z1300 A1 x 2

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final drive ratios 9 years 4 months ago #5400

  • trikebldr
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Yes! Because of that 2.52 ratio I looked at them. The problem is that the BMW's have several unique mounting and driveshaft systems that makes them harder to adapt. Some are on the left and some are on the right. And, they all seem to have such radically different mounting styles that it makes them incompatible to mating up with a Kawasaki swingarm. The Japanese bikes all seem to follow a similar design concept to each other, and almost all are mounted on the right side, except the Voyager XII!!!

At least for the ZN, the 2.833 gives almost a perfect ratio jump as to equate to another gear shift. We shall see!

But, thanks for input!

Update- Today I received the '84 Gold Wing final drive and driveshaft. I just did some rough layout measurements to see just what I will have to do to mate the Honda GW drive unit to the ZN's swingarm and it appears that just a 3/8" bolt-pattern adapter will be needed. Also, the Honda's driveshaft is longer than the ZN's, so I might be able to simply cut it, machine it clean and weld the ZN's u-joint on the end just like it is to the end of the ZN's shaft already. Could it really be this simple? Let's hope so!

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final drive ratios 9 years 4 months ago #5413

  • candp
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goooooooooooood luuck!lets us know c

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