Topic: Which transmission will work? how to tell apart?

[Jerry E.]

I need a couple new used gears for my 1975 cb750 FO transmission. I have found several used transmissions on Ebay, but how do I know whether they are from a F model motor, or the K5 motor, which is different I believe? Some are cheap enough I may buy one , and determine which it is later. All mostly are being sold for specific years, with no mention of exact model numbers.Should I look for a 1976 transmission, to eliminate any confusion?

[ekpent]

Your best bet is to buy from a reputable seller who knows what he has for sale.Ask what the engine vin #  is for instance that the parts came from or see what other parts from the same bike he may be selling to determine the exact year.  Dealer parts lists exploded views are handy for comparing parts numbers also from other years to determine compatibility. As far as I know the 75-76 F bikes did have different gear ratios in the tranny than did the K model so best to shop carefully.  Is yours jumping out of second or fourth by chance ??  May need shift forks also.

[BeSeeingYou]

According to the info I have (Honda sales brochures listing specs for 1976)  the only gears that are different are 4th and 5th.

 76 750K             76 750F
1  2.500 : 1           "
2  1.708 : 1           "
3  1.333 : 1           "
4  1.097 : 1        1.133 :1
5  0.939 : 1        0.969 :1

[Jerry E.]

I have never riden this bike. Bought from salvage yard, unrunning. The 2-3 gear has several teeth with the edges missing. Will "FO"/"K" trannys swap between cases?