gear ratios

I am thinking about doing a 6 speed swap on my 650. I just want to get some information about gear ratios. As I understand it; it is figured as # of teeth on the output over # of teeth of the input.

Some numbers for a 1987 750r,

Input Output Ratio
1) 13 38 2.92
2) 16 34 2.13
3) 21 35 1.67
4) 21 29 1.38
5) 23 28 1.22
6) 24 26 1.08




please let me know if I have missed something. Also please note, I am not saying that a 750 r tranny drops in, I'm just trying to figure out some gear ratios.

That all looks right. But, you have to consider that your stock ratios are:

1st 2.33
2nd 1.63
3rd 1.27
4th 1.04
5th 0.89

So if the 87' transmission is compatible take into consideration that the 87 transmission is a higher ratio (slower, more torque) then the 4th gear of your standard transmission. So your bike will tear of the line, rapidly go through all 6 gears rapidly and then be redlined out at about 94.18 mph. Without slippage. it might be good for a small tight and twisty track but for anything else I would suggest going to a lower ratio on your final drive.

I have gotten the stock, as well as the gpz550 which is as follows:



KZ550
Gear ratio
1st 2.57
2nd 1.78
3rd 1.38
4th 1.13
5th 0.96
6th 0.85


I know my bike feels gutless in 5th already, and I am wondering if a second overdrive is really what I am looking for.



::edit:: BTW thanks Becker for the quick and informative response. Where would you look to improve on the stock gearing?

Oh ya thats assuming that you have a 25" diameter tire around the outside.

ya the 650 can get over 100 and then it slowly creeps forward to an indicated 119 on my bike. But of course I do that on only closed courses. The difference in speed between 4th and 5th on the 650 is almost nonexistent on the top end. It's just the RPM's that differ. In reality 5th is great for cruising down the highway. If you go to the 550 transmission you could keep the cruising speed and around town easiness in 6th but kick it down to fifth for a split between the stock 4th and 5th and a good run at top speed.

1989 zx600 tranny gears


input output ratio
1st 14 36 2.57
2nd 18 32 1.78
3rd 21 29 1.38
4th 24 27 1.13
5th 26 25 0.96
6th 27 23 0.85



looks like the early zx6 used the same tranny as the 550.

Ok, I know the zx750 tranny is more close ratio, and may offer a lower top end, but I am worried the zx600 or kz550 tranny will be to tall and leave the bike feeling limp...

However now that I think about it, I would bet the zx600 (even an old 89) felt anything but limp....

I have been playing on this gearing/speed calculator...

www.gearingcommander.com/

great place to go for folks like me, wondering about how there bikes will react to different changes. I am sure the "top speeds" are not including wind resistance or other real world factors, but it is great to compare differences.


I am hoping that my bike will be able to drive the zx600 tranny with +1 -2 sprockets and still feel plenty sporty...