Transmission Gear Swapperoo

VegeKev · Post by **VegeKev** » Wed May 15, 2013 5:02 pm

G'day Benly People,

Has anyone done the 2nd and 3rd gear swap between the mainshaft and countershaft?....And if so was the run through the gears any better?

Just wondering as after taking the old girl for her first road spin the other day (

....50MPH....

) there does seem to be a rather large jump from 1st to 2nd and from 3rd to 4th. I've read that the swap is easily done and that it was done back in the early scrambler days to reduce the larger jumps in gearing....

Cheers,
Kev.

ByTheLake · Post by **ByTheLake** » Wed May 15, 2013 5:53 pm

Nope, never tried swapping gears. I do agree that the 3 - 4 shift is tall. If I hold out 3rd gear to 45-50 MPH, then the revs are high enough for me to take 4th gear to 55-60 with little trouble. If I shift into 4th too soon, it takes a while to get the speed up.

I don't expect too much from these little bikes, so I generally take it easy.

Larzfromarz · Post by **Larzfromarz** » Wed May 15, 2013 7:30 pm

I believe this was called "X-ing" and was useful with the Superhawk 305cc. I've not heard of it with smaller cc engines. Can't wait to hear what Sam says.

Sam Green · Post by **Sam Green** » Thu May 16, 2013 2:15 am

What Sam says.

Kev's is a wider ratio gearbox to what you guys have.

To add to what Larry said, I've only ever heard of the swap on the 250 and 305 models.

Sam.

Sam Green · Post by **Sam Green** » Thu May 16, 2013 2:41 am

C92/C95 CB92/95/CA95 My race box

13/34 = 2.615 14/33 = 2.350 18/29 = 1.611
18/29 = 1.611 19/28 = 1.470 21/26 = 1.238
21/25 = 1.190 23/24 = 1.043 23/24 = 1.043
25/22 = 0.880 25/21 = 0.840 25/22 = 0.880

Some pics of the three boxes in this thread.

http://forums.sohc4.net/index.php?topic=46104.125

Sam.

VegeKev · Post by **VegeKev** » Thu May 16, 2013 6:04 pm

Thanks for the info Sam, much appreciated....again!

Looks like what I'm after is a CA95 transmission....is there any difference between the early and late (64? onward) transmissions?

Kev.

Larzfromarz · Post by **Larzfromarz** » Thu May 16, 2013 6:11 pm

Hey Sam, what was the weight on that 73 bike and was that the 87mph (not kph right?) bike?

VegeKev · Post by **VegeKev** » Thu May 16, 2013 7:17 pm

Sorry.....another question...

Is the CA92 transmission the same as the CA95?

Thanks,
Kev.

Sam Green · Post by **Sam Green** » Fri May 17, 2013 2:04 am

VegeKev wrote:Thanks for the info Sam, much appreciated....again!

Looks like what I'm after is a CA95 transmission....is there any difference between the early and late (64? onward) transmissions?

Kev.

Not in the ratio department but I did have a box that had a different clutch shaft. The hole in the end of it where the push rod comes through, it was a smaller diameter and wouldn't accept the liffter.

Sam.

Sam Green · Post by **Sam Green** » Fri May 17, 2013 2:05 am

VegeKev wrote:Sorry.....another question...

Is the CA92 transmission the same as the CA95?

Thanks,
Kev.

I'm not sure Kev, there were only a handful made.

Sam.

VegeKev · Post by **VegeKev** » Fri May 17, 2013 2:32 am

Once again...Thanks heaps.

Kev.

Sam Green · Post by **Sam Green** » Fri May 17, 2013 3:01 am

Larzfromarz wrote:Hey Sam, what was the weight on that 73 bike and was that the 87mph (not kph right?) bike?

Larry, I built the 73 bike to have a go at road racing before I got to old.
I did one event and then the track (a road circuit) go closed to any further racing.
I let a few friends use it for sprinting, that's one of them in the red leathers in the picture above. The bike is now being rebuilt as a mobile test bed.
I think it weighed in around 180lbs.
The bike # 175 at the top of the page and also in most of the other pics painted red is the one that recorded 87mph back in the 60s.
It was a UK spec C95 (stock 13Cbhp motor) that one weighed in at about 150lb at the time.

Sam.