Topic: CB750 transmission interchangability

[brandEn]

I need a new transmission for my K4. This was a high mileage engine and I have worn gear dogs and some of the bushings seem way to loose. I see some later model (75-78 K&F) lower mileage transmissions on ebay. Is there anything I should consider before swapping out gear clusters? Seems it should be no problem but just want to be sure.


Also, if anybody has a good transmission to sell be sure and let me know!

[ekpent]

Be best to stay as close to your year as possible. Do not consider The F models or later post 76 K as there are differences there.  Check parts fische numbers to be certain on other years and make sure the seller really knows what year etc.,history they got before you buy. 

[Don R]

77/78 use the large chain and the sprocket mounts farther out. F models have different ratios for 4th and 5th gear. You may be able so swap it all but don't try to mix parts. I bought an F trans off E-bay for just such a project. I got the trans, gears, shafts, shifters points plates and advance unit for $30. The guy listed the auction wierd and it was hard to find.

[brandEn]

yea, what I was wondering is if I would be ok just changing the whole deal. Not swapping out individual gears. I know the later F models have 630 chains (I have one) but I think the full tranny cluster will work, just not positive.

[excellrec]

I wasn't even able to use all the transmission gears to swap one 77f tranny with another 77f tranny.  what is the reason for the swap?

[brandEn]

I wasn't even able to use all the transmission gears to swap one 77f tranny with another 77f tranny.  what is the reason for the swap?

uh wear... the whole reason I started this thread.

[Hinomaru]

Brandon, If it’s in your budget ... How about one of those transmissions from Cycle X? (scroll down a bit)

http://www.cyclexchange.net/Engine%20Parts%20Lower%20End.htm

Just might be the way to go since you wanted back cut gears to go along with the 836 kit and headwork.

Does your shift drum needs replacing?  If so, look for the Honda ‘modified shift drum’ for more positive shifting:

http://data.sohc4.net/SB750/750_40.pdf

[brandEn]

Brandon, If it’s in your budget ... How about one of those transmissions from Cycle X? (scroll down a bit)

http://www.cyclexchange.net/Engine%20Parts%20Lower%20End.htm

Just might be the way to go since you wanted back cut gears to go along with the 836 kit and headwork.

Does your shift drum needs replacing?  If so, look for the Honda ‘modified shift drum’ for more positive shifting:

http://data.sohc4.net/SB750/750_40.pdf

Yea that might be the way to go.

Thanks for the shift drum link, haven't seen that. Also check out my build thread. Found pics of that Japanese Market silver/blue K4...