Here's a strange idea I had.

4th gear is geared 22:23 or 0.9565. 5th gear is geared 23:26 or 0.8846.

Would it be possible to take the 22 tooth gear from 4th gear and combine it with the 26 tooth gear from 5th gear to make a ratio of 22:26 or 0.8462? Are all the gears the same with the exception of the tooth count?

I know a chain conversion or Kawi pulley swap would be easier but if this might be another option.....

Anyone out there torn down their transmission enough to figure this one out?

I've not been inside the transmission but I would be forced to ask myself how gears with different numbers of teeth mesh unless the centers are adjusted to make room. The more teeth, the greater the circumference.
Yeah, math is involved.

Don't the drive gears ride on one shaft and the driven gears on another? Wouldn't the spacing already be set?

Without actually measuring, I'm assuming that a gear with twice as many teeth is twice as big in diameter. Probably not though. That would be too easy!

ASSUMING that a 5" diameter gear with 10 teeth is half the size of a 20 tooth gear that measures 10" in diameter, the idea could work, right?

Is there any resource that anyone has found that might show the dimensions of the gears that we would need? Is the shop manual helpful in this regard?

Oh well...just looking for another option.  Thinking outside the box is called progress in some circles...except when you're dealing with a bike that's not compatible with any other product out there. Does that make us special?  

I agree. I'm too chicken just to make some measurements.  

Hi Kris,

In reply #4, you were saying about a 5" 10 tooth should be half as big as a 10" 20 tooth.

In your example, the spacing between the teeth on the bigger gear will be much larger.  You're dealing with the distance around the outer edge of the gear which is diameter difference*pi. 5*3.1415279=~15.7" difference in distance around.

You have to calculate the diameters of the mating gears such that the tooth spacing matches for the distance around and gives you the correct distance between centers.  New gears could be made by someone with the knowledge and equipment to cut and harden them if you sent them the drawings of what you wanted.  It would cost you at least a few hundred bucks. But, you could conceivably change the ratios.

There are also other problems dealing with the amount of torque put on the gears changing as their size changes. The gear engagement tries to force the gears apart when power is applied. Shafts and bearings have to be able to handle the load. The teeth have to be small enough to mesh well at the desired ratio.  Too small and they can't take the load and strip off.  Too big and very noisy and lots of vibration causing excessive wear.

My hat's off to the designers of transmissions.  There's so much to thnk about and work with to just come up with a plausible design that will have to be refined from R&D making prototypes and trying things.

I hope something I've said makes sense.  I bet Dave can explain it much better than I.

Steve H:
My example was just a simple one (concerning the math).  I didn't want to get too detailed with the circumference example. It would have been too confusing.



WD:
A local shop that makes gears from scratch? Is this fairly common?

I was kind of hoping some brave person would tear their transmission apart and try this so I could copy them!    I'm a smart guy (aren't we all?  ) but I'm not the type of person to try this on my own.

That's my excuse too!