Topic: CB 750 for Performance Use

[TurboD]

I would like to know the differences in the 750 engines, mainly which engines and or parts that would be best for performace use. I'm assuming the 77-78 750F would be the best.

What makes the Later 750F Better than others?

[Bill/BentON Racing]

Combustion chamber, bigger valves, and bigger output shaft bearing, more stuff, those the performance ones off top of my head, Bill
Cam sprocket not slotted ,but was drilled and lightened.

[TurboD]

Thanks.

I've read somewhere that the bottom end is stronger, anyone know what the differences might be?

[Jerry Rxman Griffin aka MuthaF'er]

Rod bolts/nuts but that only counts if you use stock rods.

[voxonda]

Castings are firmer, due to sound regulations. But therefor also heavier.

[TurboD]

Thanks

So the Cases are thicker.
Rod bolts are better
Bigger valves
Combustion chambers smaller (how much?)
Output shaft is larger

Anything else worth noting?

Second question as to not start another thread.
Does anyone have specs on the different stock camshafts??

[Don R]

The combustion chamber is a Hemispherical shape in addition to it's compression.

[dragracer]

As far as the later F Models, I've discovered that the clutch basket, hub and cover are different although i'm not so sure that means better. They also use a different clutch pack than the earlier models which could be better as well. I found out Honda  no longer offers one of the steels so making up an original clutch pack may not be so easy.  I got lucky and my good friend Bill did find me that odd OEM steel plate on Ebay when i was putting my bike back together. APE does sell the extra clutch disc pack but i haven't used that yet. I just prefer OEM clutches for my race bikes when possible.

I echo all else everyone has mentioned. In a hi po build, i would rather start with the later F model parts. I also like the PD carbs more due to the accelerator pump feature.

[TurboD]

I always use stock clutches in my Kawasakis, I like the feel and they have held up to 300 HP without any problems.

[dragracer]

I always use stock clutches in my Kawasakis, I like the feel and they have held up to 300 HP without any problems.

Yes, to me stock works great. In my car tire top gas/top sportsman bike, i've had  consistent 1.10 sixty foot times and haven't broken any plates yet.

[TurboD]

Frank I sent you a new email.

[BPellerine]

are the chambers not bigger not smaller?bill

[jweeks]

"F" model carb boots aren't available, which makes for creative solutions needed for the mounting of aftermarket carbs most people go to.

[754]

The f boots mount to PD carbs,  I think. Most others I think use. The regular boots..

[Big Jay]

are the chambers not bigger not smaller?bill

Yes the F2 chamber is bigger, not smaller

[Jerry Rxman Griffin aka MuthaF'er]

"F" model carb boots aren't available, which makes for creative solutions needed for the mounting of aftermarket carbs most people go to.

Yes they are, just not from Honda.

[Jerry Rxman Griffin aka MuthaF'er]

As far as the later F Models, I've discovered that the clutch basket, hub and cover are different although i'm not so sure that means better. They also use a different clutch pack than the earlier models which could be better as well. I found out Honda  no longer offers one of the steels so making up an original clutch pack may not be so easy.  I got lucky and my good friend Bill did find me that odd OEM steel plate on Ebay when i was putting my bike back together. APE does sell the extra clutch disc pack but i haven't used that yet. I just prefer OEM clutches for my race bikes when possible.

I echo all else everyone has mentioned. In a hi po build, i would rather start with the later F model parts. I also like the PD carbs more due to the accelerator pump feature.

Eliminated noisy clutches.

[dragracer]

"F" model carb boots aren't available, which makes for creative solutions needed for the mounting of aftermarket carbs most people go to.

Jerry,

Where can we get the aftermarket F model boots?? Mine are getting bad now.
Yes they are, just not from Honda.

[jweeks]

      Jerry- I'll second that question. F manifolds - OEM gone, http://www.claussstudios.com/  no longer offered. What's your source?

      We want bigger carbs to feed the F head. K manifolds aren't the solution for racers. Cut silicone elbows?

[kmb69]

Obviously, I am not Jerry, but I just bought a set of these and they look pretty nice. Maybe a little harder than OEM. I have not used them yet so I cannot vouch for them.

http://www.partsnmore.com/parts/honda/cb750f

Carb Holder Set  #48-0758 | Honda CB750F (1977-1978)
Carb Holder Set (Set of 4).
Replace those old cracked or dried up carb holders with a brand new set!
Each holder is numbered 1-4 just like the original OEM holders.
Replaces OEM#'s 16211-410-000, 16212-410-000, 16213-410-000, 16214-410-000.

Keith

[Jerry Rxman Griffin aka MuthaF'er]

There you guys go begging again......      Probably the same as Keith's.

http://www.vintagecb750.com/products/73/featured-products

You may as well also buy that new wiring harness for your F you've always wanted but could never get 

[dragracer]

There you guys go begging again......      Probably the same as Keith's.

http://www.vintagecb750.com/products/73/featured-products

You may as well also buy that new wiring harness for your F you've always wanted but could never get 

Thanks for the info gentlemen. The only part about getting new boots is that i will have to take my die grinder to them to open them up for the flatslides which entails an offset cut in the boot to fit the carb spacing. Too much work!!!

Wiring harness? What wiring harness?? For me its a homemade race harness. Power to a main toggle switch from the battery, power out of the switch to a tether kill, power from the kill back to the MSD box. All connections to the coils and the pickup come out of the MSD box. Done!!! Lol.

[Old Scrambler]

Great info on the intake sources...........I have original for K and F to play with on my Hypo-750 build.........but just in case they leak.........thanks.  I have reamed a K intake to fit a Mikuni 32mm flat-slide. Jerry saw it at Bonneville. Now plan to adapt the intakes to a set of 33mm flat-slides.

Question related to the thread topic. Does anyone have the stock cc comparison for the K vs. F2 head chambers?   

[TurboD]

Does anyone know where I might find specs for the different Honda camshafts?

[cbr954]

Question related to the thread topic. Does anyone have the stock cc comparison for the K vs. F2 head chambers?   
[/quote]

One of my K heads cc at 22 cc another one that was smoothed out measured 24cc.   My smoothed F2 head was 29cc.