Topic: I think I've got an "F" head that was converted to "K" valves? (Pics inside)

[jtb]

Now you've done it....  I just had to get my camera out.

This is what I was referring to pertaining to the 392 casting and the (barely visible in my light condition) hand stamped K 8. No hand stamped F on the bottom. My other 392 75 F head is in the garage with a tank obscuring the markings, it's late and I don't want to take the bike apart right now. I do not believe you have a F head. Studs can be removed so thats probably irrelevent. I think you have an earlier K head thats been reworked with 33.5mm intakes and 28.5mm exhausts which are also available. 

The 77&78 F heads will have 410 cast in this place instead of 392.

[kos]

I see that someone referenced a F3 CB750...what is that?


Mark @

[kos]

Someone asked for help on Turbo Cam specs. Norris Turbo Profile can me made on a good core by Mega Cycle. Specs are .342" lift Intake 215 duration, lobe center 109.5 degrees.
.312" ift ex 222 duration, lobe center 110 degrees (FYI, other than lobe centers, a bit more INT lift... this is very close to STOCK cam) Stock is: .315 lift INT, 220 duration & .313" Lift EXH, 235 duration.

REMEMBER... Hard welded cams are far superior in wear characteristics than billet cams. Same for hard faced rocker arms.

Speed costs money


KOS

[jtb]

I see that someone referenced a F3 CB750...what is that?


Mark @

78

[scondon]

I see that someone referenced a F3 CB750...what is that?


Mark @

78

Commonly referred to as a F2 the '78 750F is a F3

[kos]

Honda uses only CB750F and CB750F2...never was a F3.

Let's keep it simple....


KOS

[scondon]

Honda uses only CB750F and CB750F2...never was a F3.

Let's keep it simple....


KOS

Honda lists it as a F3 in both the general SOHC/750 and '78 750 shop manuals. That is where I got this info

[kos]

Yes, you are correct.

I stand corrected.

Those books are printed in Japan and sometmes the American Honda designations ended being different.

How do I know that?

Twenty years as Honda dealership mechanic (not technician...they replace parts...MECHANICS fix things!)

Ten years a  Senior Factory Service Rep for America Honda Motor Company. Territory..MN, ND, SD, MT, WY & NE.


KOS

[scondon]

Yes, you are correct.

I stand corrected.

Those books are printed in Japan and sometmes the American Honda designations ended being different.

How do I know that?

Twenty years as Honda dealership mechanic (not technician...they replace parts...MECHANICS fix things!)

Ten years a  Senior Factory Service Rep for America Honda Motor Company. Territory..MN, ND, SD, MT, WY & NE.


KOS

     This is why I'm more than happy to just use the F2 distinction for both years. With you, Buzz, Big Jay, Mrieck*, and others that I rely on for info/parts/machining it definitely helps keep it simple. If I tried to order parts for a '78 F3 from APE I wouldn't get very far as they sell stuff for a very different F3

* actually Mike lets me call it "that #$%*ing valve eater"

[NitroHunter]

I'm pretty sure the F-2 heads were marked as 410 and you can't mistake the oblong combustion chamber when the K & F-2 are side by side. And the big valves are a dead give away.

[kos]

Yes, If you flip them over and just look at chamber you can tell without even a side by side comparision.

F2 is all I ever heard when I was a rep and buying back engines due to valve retainer failures.


KOS

[Jerry Rxman Griffin aka MuthaF'er]

The 75 750F was referred to as the K0 Super Sport in many Honda parts books, etc aka F0 unoffically
The 76 750F was referred to as the F1
The 77 750F was referred to as the F2
The 78 750F was referred to as the F3

[kos]

But... we are still going to call the 77-78 Black Motor "410" model code bikes... F2!


Because, we don't go to Starbucks anymore, because we don't liked saying "I want a Verdi" or a "Grande" or whatever they try make you say..just to get a cup of joe.

KOS

[MRieck]

The 75 750F was referred to as the K0 Super Sport in many Honda parts books, etc aka F0 unoffically
The 76 750F was referred to as the F1
The 77 750F was referred to as the F2
The 78 750F was referred to as the F3

Then there was the CBR600F2, CBR600F3........

[scondon]

Because, we don't go to Starbucks anymore, because we don't liked saying "I want a Verdi" or a "Grande" or whatever they try make you say..just to get a cup of joe.

  That's good

     Only here on this forum do we strive to make the F2-F3 distinction. A number of changes to the bodywork, carbs, and even engine make it necessary to be clear on which model we're working on. Everywhere else it is a "cup of coffee". Because of my Lester wheel people often look at my bike and say they had a "Kawasaki" just like mine back in the day and I just say "cool,"

[kos]

Come on...this is not the all Honda forum.  Who gives a s**t about a 600? You see any major changes between 77 and 78?


KOS

[754]

Kos, what is your opinion of the black 78F in stock trim vs a KO?

Also what are the weak points of the black F'er?

 I am thinking I should trade the black motor I have for a 71 or 70.. it just seems harder to get parts.

 Which head do you prefer to run?

[Jerry Rxman Griffin aka MuthaF'er]

Now Mike, you know 600's aren't real F's. Those are R's with a F stuck on the end to imitate our bikes    Don't do that to the Million Dollar CB 

Now Starbucks is a different story. First time I went into a BigBucks coffee shop was due to a business meeting when I sold my business. I had to ask that friggen geek how to order a damn cup of coffee. I asked her "can you get just a plain cup of coffee in this place?" Geez.

Mark, glad to see you hanging out with us mere mortals. Stick around. We're mostly harmless 

Hey Frank, why don't you keep that F2! and stick some big valves in it. I know you and 1080 could do some serious #$%*!

 

[754]

I would rather have a 71 motor..
Beside I got 2 F motors since last summer...black ones.

I have a K head with bigger valves and ported that will go on my next engine.. got to tear into my motor soon..see how bad it is..

I was surprised at how obvious the cam profile was on the 78 F.

[kos]

What engine would I go with.....

For just the simple reason of parts availablity...I would go with anything prior to 1977-78. I have custom valves made for the F2 heads , but at limited quantities (I have no demand at all) they are $70.00 each and might go up! I will at some point... design/make up, with my supplier KPMI, spring kits and Ti retainers for the F2 valves, but will go back to original early (1969-1976) style keeper grooves. There are some great cams out there for F2's from Mega Cycle.

If I can help...let me know.

KOS

[scondon]

........ I have custom valves made for the F2 heads , but at limited quantities (I have no demand at all) they are $70.00 each and might go up! I will at some point... design/make up, with my supplier KPMI, spring kits and Ti retainers for the F2 valves, but will go back to original early (1969-1976) style keeper grooves. There are some great cams out there for F2's from Mega Cycle.

If I can help...let me know.

KOS

      I've been swapping out the head and cylinders on my F2's and using 75-up K parts for an easier introduction to big-bore engine building. I keep passing that F2 head on the bench and thinking "some day".

      Do you ever cross paths with Buzz at Dynoman?

[NitroHunter]

For those who've never seen this, here is a picture of the keeper groove difference between K and F-2 valves.
These shown are Manleys, K at top, F-2 lower