Author Topic: classic race gearbox (Read 852 times)

mad mike · « **on:** July 01, 2022, 10:20:01 AM »

Greetings gentlemen, ...... Help/ advice requested please, ..... Building a classic race CB750 ... What is the best gearbox, or combination/mix of standard parts ? ..... Nova box is, " a no go" due to costs at the moment, and also best final drive ratio setup ? .... I have a few boxes covering several years , from early to F1 /2? Thanks in advance . Mike.

PeWe · « **Reply #1 on:** July 02, 2022, 04:54:07 AM »

CycleX close ratio gearbox?
Scroll down....
http://www.cyclexchange.net/Engine%20Parts%20New%20Lower%20End.htm

Don R · « **Reply #2 on:** July 02, 2022, 06:46:33 AM »

The f2 gear set comes with the wider output shaft but can be swapped to the older one. On a street/highway bike I like the F ratio with a taller sprocket.
My old K0 was revving 5200 on the highway yesterday, the cam was loving it.

mad mike · « **Reply #3 on:** July 03, 2022, 05:57:39 AM »

Hi Don, .....Thanks for the info. Best regards. Mike.

PeWe · « **Reply #4 on:** July 03, 2022, 07:59:30 AM »

Quote from: Don R on July 02, 2022, 06:46:33 AM

The f2 gear set comes with the wider output shaft but can be swapped to the older one. On a street/highway bike I like the F ratio with a taller sprocket.
My old K0 was revving 5200 on the highway yesterday, the cam was loving it.

I have an ongoing engine build that has a later transmission.
It looked so good and not much used so I had to buy it. Complete crank with rods and alternator + starter gear from same engine.

The last gear on outgoing shaft got a K2-K6 shaft + new ball bearings.
4th and 5th will rev a little bit more than the earlier K.

I think it will it be like 4-5 run 17:18 when using 18:48 sprockets.

2-4 now undercutted so just waiting for a refurbished primary chain hub with new rubber inside.

Later outgoing gear is different and must be used with later transmission.
Photos before gear swap to earlier shaft.