Topic: K0 final drive bearings

[AshimotoK0]

Hi,

The final drive bearings on my '69 750 K0 are the NR 'grooved' type (with retaining ring half circular holders) but I just bought a very low mileage 1970 transmission and the these bearings on it's output shaft bearings are not grooved. Did the K1 have non- grooved bearings ('NICK' as Yamiya call them). If so how were the the bearings prevented from moving sideways in the housings? The bearings concerned are 6305NR and 6205NR

http://www.yamiya750e.com/index.php?main_page=product_info&cPath=21_53&products_id=111

http://www.yamiya750e.com/index.php?main_page=product_info&cPath=21_53&products_id=109


I think the correct Honda 6305NR bearing is 91003-259-000 which is also used on the Honda CB72 'Hawk'
and the 6205NR is 91002-300-008

Cheers !!  AshD

[mystic_1]

Yup, K1 had a non-grooved, single-row output shaft bearing.  The retainer is a full circle that sits outboard of the bearing.  The bearing cannot move inward because it's stopped by the shaft's shoulder.

I'll see if I have any pics.

mystic_1

[AshimotoK0]

Thanks Mystic,

I guess this Service Bulletin explains the change

http://data.sohc4.net/SB750/750_29.pdf

[mystic_1]

Yup!  That pretty much covers it.

You can run any of the bearings on the later crankcase design, but the early crankcase will only accept the grooved bearing because of the change to the keeper.

Pics below show the last three variations on the shafts from the chart on the first page.  Case is a "K1-style" numberless replacement case.  Also shown is the K1-and-later-style keeper.

mystic_1

[AshimotoK0]

Wow Mystic that's great. I wanted to keep all of the meshing gears on the replacement transmission. Can I use the gear from the K1 final drive on the K0 shaft?

[mystic_1]

Yes!  All variations used the same gear 23511-300-020

mystic_1