Topic: 1976 CB750F - which engine do I have

[Jerry Rxman Griffin aka MuthaF'er]

I posting a pic so everyone can see the casting number on my cylinder head.

I think the real question then is…..
What’s the difference between the F0 and F1 engines (if any at all) are the F0s just hopped up K6 engines? Did the new cams etc only come with the f1 update? Or are they both the same just different designations?

A real history lesson is needed here lol

F0 and F1 are the same engine
F0 is hopped up K6 et al higher compression + 0.2, piston tops, cam, combustion chamber design, tranny gearing, carb changes, 17 tooth front sprocket, may be missing something?
New cams came with F0, higher redline

Looking at your X3 head from that view I can not determine much of anything. ie the shape of the combustion chambers. My head is not original as a broken valve head destroyed the original at about 5,000 miles. Power shifting can be destructive. The current head I have was the replacement and it has 392, not X3. Without seeing the combustion chamber I can not say otherwise.

As a side note, Honda was suspect in installing hotter cams initially in new models to boost performance to increase sales. I discovered my original cam has 0.1mm higher exhaust lift than the others in my collection. 

[HondaMan]

As a side note, Honda was suspect in installing hotter cams initially in new models to boost performance to increase sales. I discovered my original cam has 0.1mm higher exhaust lift than the others in my collection. 

Not only SUSPECT...
I've measured 2 of them that didn't match specs, had longer valve-open intake dwell on one, and taller lift on intakes and exhausts on another. One was an early K1, the other was an early F2.

[seanbarney41]

As a side note, Honda was suspect in installing hotter cams initially in new models to boost performance to increase sales. I discovered my original cam has 0.1mm higher exhaust lift than the others in my collection. 

I think Honda was playing with very slight variations in cam specs continually throughout the entire sohc 750 model run and not changing part numbers, casting numbers, specs in manuals, etc.  I have seen the wide variety of intake port prep quality that does not necessarily line up with accepted standard of early bikes prepped more carefully/later less...some of these bikes idle so much smoother, some run so much harder...and I have not been able to form a year by year consensus.  I have ridden dozens of 'em at this point but still not enough to see a pattern.  Some perform so mediocre, others amaze.  So, when your F0/F1 does not have the the normally found 392 casting number, it does not mean that it is not original...or maybe it got swapped sometime back in history, maybe even at the dealership.  Would love to be able interview every one of these old bikes, and I bet the most clapped out, worn out one is gonna have the most, best stories.

Not only SUSPECT...
I've measured 2 of them that didn't match specs, had longer valve-open intake dwell on one, and taller lift on intakes and exhausts on another. One was an early K1, the other was an early F2.