Author Topic: Stock CB750 Cam Identification (Read 13368 times)

TurboD · « **on:** January 25, 2016, 02:55:42 PM »

Does anyone know if there are ways to identify the different stock 750 cams? Casting marks or machining etc. ?

Bill/BentON Racing · « **Reply #1 on:** January 25, 2016, 03:15:17 PM »

Yes, somewhat....might be top secet,lol, what you got?

, Bill

gschuld · « **Reply #2 on:** January 25, 2016, 04:00:16 PM »

Dave,

Could you be more specific? Are you try to identify IF you have a stock cb750 cam or not, or are you trying to identify which version of cb750 cam you have?

Going by cast markings alone would only present part of the ID since many performance cams were reground stock cams.

Base circle and max lift numbers( plus no obvious long duration cam lobes), combined with casting marks should help ID it as an unmodified factory cam.

Tell us what you have and we'll see if we can identify it. I could measure and post pics of a factor early K cam if that would help.

George

TurboD · « **Reply #3 on:** January 25, 2016, 04:25:14 PM »

Yes I am trying to see if there is a way to identify the different stock 750 cams, by castings and or stampings. The K's 72-76, K's 77-78, 77-8F's.

Bill/BentON Racing · « **Reply #4 on:** January 25, 2016, 04:52:29 PM »

Yes on F2's I believe, info and pics later tonight, Bill

NalleyRacing · « **Reply #5 on:** January 25, 2016, 05:04:48 PM »

All the 78F model cams ive pulled from stock motors have these raised circles on them. Usually with spaces inbetween as shown here and I have one with a solid ring all the way around like the second pic..

I also have one unique cam that looks to be a reground stock but with almost no seperation between lobes and part of the sprocket carrier shaved and stamped with 2501

gschuld · « **Reply #6 on:** January 25, 2016, 05:17:06 PM »

This might be a reasonable start regarding measured specs.

George

Bill/BentON Racing · « **Reply #7 on:** January 25, 2016, 05:24:30 PM »

Yes to the raised circle bumps and they also have index marks on rt side cam end. There's at least 3 different K grinds, 69 early KO's... C'mon Keith ,you tell 'em. The identifying uh.. mark on original cams, was then ground down, another grind, then the ones with no mark, another K grind,that's 3rd , then 75K...maybe different, early F1's, 77/78K?, not sure about them, Bill

scottly · « **Reply #8 on:** January 25, 2016, 05:35:32 PM »

Trey, the cam in the third pic looks like it has a small base circle, indicating it may be a re-grind?
I have a K7 cam I can measure.

NalleyRacing · « **Reply #9 on:** January 25, 2016, 05:46:08 PM »

Yeah its unique for sure. It came from the spare 915 turbo motor built by Tom Elrod.. Not sure the specs or who worked on it.. Ive kept it around for awhile now

I also have a K5 cam I can check out as well.

gschuld · « **Reply #10 on:** January 25, 2016, 06:00:34 PM »

Late k1 cam

George

gschuld · « **Reply #11 on:** January 25, 2016, 06:01:47 PM »

Same k1 cam

George

Bill/BentON Racing · « **Reply #12 on:** January 25, 2016, 06:32:07 PM »

I'll trade you one burnt too hell HA piston for a turbo cam? Lol!

NalleyRacing · « **Reply #13 on:** January 25, 2016, 07:25:59 PM »

Are you reffering to our new custom "blown" ash tray Mr.Benton??

Haha ill trade ya for one of the good ones and a small shifty cylinder thangy

Oh yeah and call me!

Bill/BentON Racing · « **Reply #14 on:** January 25, 2016, 08:35:46 PM »

Bill Pellerine got them! Yes the custom ash tray by Trey! No two look the same! Little pricey though! Comes with holey fender too! LMAO I'll call later.

NalleyRacing · « **Reply #15 on:** January 25, 2016, 09:17:25 PM »

... Holey fender

dragracer · « **Reply #16 on:** January 25, 2016, 10:57:42 PM »

Dang it fellas, will we never hear the end of that debacle.

PeWe · « **Reply #17 on:** January 26, 2016, 01:32:28 AM »

The first sandcast cam would be good to identify on a photo. Really bad that Honda had to downgrade the power. It was the environmental guys, right?
Honda should have upgraded the engine and overpowered the Kawasaki Z1-900 as stock bikes. 1972-73

Bill/BentON Racing · « **Reply #18 on:** January 26, 2016, 05:35:16 AM »

I've sold all mine, Keith, flip side is once identified, they may be more out there. Just pickin on kmb69 cause he's got a ...few! Lol, Bill

kmb69 · « **Reply #19 on:** January 26, 2016, 06:52:17 AM »

As far as I know, there are no identifiable markings on the Sandcast and K0 cams.
They basically LOOK the same through K6. You have to measure them to distinguish.

TurboD · « **Reply #20 on:** January 26, 2016, 06:55:10 AM »

Thanks for all the input and keep it coming. Have we determined a formula to figure out one from another?

Through my research from my many old and new Honda shop manuals. I have come to conclude that there are 4 different cams used, The K models early to 76, K 77-78, F models 77- 78 and the Automatic's.

I don't know for sure and would like to see proof. I have heard the mention of a early sandcast cam being different and possibly hotter, I have not seen specs in any manuals to confirm this. The early and sandcast bikes are said to be faster or more powerful, I don't believe this has much if anything to do with the engines internally. The early bikes simply had the best air boxes, pipes and jetting, Noise complaints and regulation prompted change on later models.

kmb69 · « **Reply #21 on:** January 26, 2016, 07:49:13 AM »

Quote from: TurboD on January 26, 2016, 06:55:10 AM

.....
I don't know for sure and would like to see proof. I have heard the mention of a early sandcast cam being different and possibly hotter, I have not seen specs in any manuals to confirm this. The early and sandcast bikes are said to be faster or more powerful, I don't believe this has much if anything to do with the engines internally. The early bikes simply had the best air boxes, pipes and jetting, Noise complaints and regulation prompted change on later models.

All the Sandcasts and SOME EARLY K0s had the same HOTTER cam albeit no distinguishable markings. They were in fact much faster. In fact, Honda claimed 12.6 sec 1/4 mile times on their original brochures. I know for a fact they would run high 12's all day long as I used to race a couple of them every weekend back in the day. There were a couple of reasons besides the cams that made the Sandcast faster. The factory actually hand smoothed the ports on the early heads and the very early Sandcasts came with what are called Lotus Roots exhaust. They were essentially straight megaphones when the baffles were removed. They also had a different spark advancer.

I will never forget the Bowling Green race in 1970 when a Sandcast set a new record in the Stock Class. Upon teardown inspection, he was disqualified for "head porting". His engine had never been apart and came from Honda with the ports slicked up. You can see the grinding marks in the early heads. They were substantially detuned when the K1 was released.

Jerry Rxman Griffin aka MuthaF'er · « **Reply #22 on:** January 26, 2016, 10:10:34 AM »

My take: early K's, mid K's, early F's, late K's, late F's.

I recently took my cheap calipers to lobe heights and my early 75 F cam (original owner) had an exhaust lobe 0.1mm higher than a late K or late F cam.

Bill/BentON Racing · « **Reply #23 on:** January 26, 2016, 10:17:56 AM »

I have pics on how to identify 69/K0 cam...but have to find them, the last one I sold you Keith has the identifying marks if you got pics, the one that had been pickled for like 30 years, came out of my buddy's 69 sandcast endurance racer, he went to a Yoshimura cam. Really nice 69 cam it was! Bill

dragracer · « **Reply #24 on:** January 26, 2016, 10:29:54 AM »

So are we to conclude from all posted so far that the sandcast and K/0 cam is the better choice as far as stock grinds are concerned?? Seems the way to go for an economical street build or a stock motored ET bike.

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Author Topic: Stock CB750 Cam Identification (Read 13368 times)