Author Topic: Which year had the most HP? (Read 6227 times)

phil71 · « **on:** March 10, 2012, 11:11:41 PM »

I'm trying to find out which of the SOHC 750s made the most power and torque, and what RPM range that happens in.
Thanks in advance to anyone who knows!

harisuluv · « **Reply #1 on:** March 10, 2012, 11:45:48 PM »

69 had the most hp. They were nerfed as the years went on.

754 · « **Reply #2 on:** March 10, 2012, 11:47:37 PM »

The most horsepower..that would be the years Russ Collins, built the triple...

Jerry Rxman Griffin aka MuthaF'er · « **Reply #3 on:** March 11, 2012, 12:02:27 AM »

77/78 F then 69/70 K and 75/76 F were equal with 77/78 K right behind

TwoTired · « **Reply #4 on:** March 11, 2012, 12:06:32 AM »

With its bigger valves, hotter cam, and higher compression ratio, why wouldn't the 77-78 CB750F have the best stock HP? It has a higher RPM red line as well.

Listed as: 73 hp @ 9500 rpm

754 · « **Reply #5 on:** March 11, 2012, 10:37:15 AM »

That is a question my K3 with a header asked itself all the time..

mycb750k6 · « **Reply #6 on:** March 11, 2012, 11:23:38 AM »

I thought the 69 Ks were 67hp and the late Fs were 72 hp, no?

754 · « **Reply #7 on:** March 11, 2012, 11:55:12 AM »

At any rate those are claimed horsepower ratings. Look to the track results or what your bike can do against others..let that count..

TwoTired · « **Reply #8 on:** March 11, 2012, 12:07:37 PM »

Quote from: 754 on March 11, 2012, 11:55:12 AM

At any rate those are claimed horsepower ratings. Look to the track results or what your bike can do against others..let that count..

Phil's question was about power and torque.

There were far less 77-78 CB750F models than others, and therefore less people to hot rod them and enter them in track battles. Now, if you just want to brag about how yours is better (or bigger) than someone else's, then post dyno numbers that are contrary to published data, please.

I'm NOT saying the the published number didn't come with a longevity cost. But, that is pretty much true of every engine that is hot rodded and asked to deliver that hot rod power constantly.

Cheers,

BeSeeingYou · « **Reply #9 on:** March 11, 2012, 12:25:38 PM »

Quote from: TwoTired on March 11, 2012, 12:06:32 AM

With its bigger valves, hotter cam, and higher compression ratio, why wouldn't the 77-78 CB750F have the best stock HP? It has a higher RPM red line as well.

Listed as: 73 hp @ 9500 rpm

Because it doesn't fit into the mythology of the all powerful magical perfection of the K0.

754 · « **Reply #10 on:** March 11, 2012, 01:09:32 PM »

Ok lets make it simple.. the first KOs and the last Fs have the most..

but dont come crying to me if a 77/78 F ,in real life, does not deliver what some on here and some magazine tests told you it could do..

MCRider · « **Reply #11 on:** March 11, 2012, 01:14:37 PM »

Quote from: 754 on March 11, 2012, 01:09:32 PM

Ok lets make it simple.. the first KOs and the last Fs have the most..

but dont come crying to me if a 77/78 F ,in real life, does not deliver what some on here and some magazine tests told you it could do..

That's a pretty good comment. I think the 77/78Fs had the most HP which was the question.

But i also think they were heavier than the K0, and slinging around a 630 ORing chain. Twin discs on front, a little longer I think. Kinda takes the edge off the HP advantage.

754 · « **Reply #12 on:** March 11, 2012, 01:15:26 PM »

First peson to show up at my shop, gets 2 78 F motors, for 350 bucks, and a frame on wheels, set of carbs..roll that one away.. One is missing pistons, other together condition unknown... I make NO CLAIMS about what those motors will do for you..

Jerry Rxman Griffin aka MuthaF'er · « **Reply #13 on:** March 11, 2012, 01:23:28 PM »

Quote from: 754 on March 11, 2012, 01:09:32 PM

Ok lets make it simple.. the first KOs and the last Fs have the most..

but dont come crying to me if a 77/78 F ,in real life, does not deliver what some on here and some magazine tests told you it could do..

I stand by my first reply as the original owner of one of the first F's!

754 · « **Reply #14 on:** March 11, 2012, 01:31:51 PM »

Keep in mind even if the late F's had more power than a 69/70, they are heavier, bigger chain, and probably geared a lot higher..
...so even if they have more HP, they may not be as quick..

Jerry Rxman Griffin aka MuthaF'er · « **Reply #15 on:** March 11, 2012, 01:41:14 PM »

Not talking quick here but I think the same rider on all 3 bikes when new would probably STILL provide the same results I've put up. Do you have any info on the weights? I think my 75 750F was "listed" as 497 lbs perhaps??

Davidov · « **Reply #16 on:** March 11, 2012, 01:42:14 PM »

It's always disappointing that the motorcycle world doesn't get around to dyno tests like the automotive world does.
Especially on these older beasts.
Although understandable, we ride these for the enthusiasm and riding excitement.
Not like R1/Hayabusa/Jerkoff/piss stream measuring world out there.

That said.....
the late model F engines were built with the aforementioned bigger valves and whatnot.
This "black cased" engine would probably be more desirable for an individual looking to get a stock engine and build for max. power.

BobbyR · « **Reply #17 on:** March 11, 2012, 01:53:03 PM »

Probably the bike that is properly tuned and maintained will have the most HP.

754 · « **Reply #18 on:** March 11, 2012, 02:21:16 PM »

All the bikes back in the day (magazine world) had hp listed, and or were dyno tested. However this does not prevent Honda from slipping in a ringer meaning every bike on the street may not deliver the same performance...

phil71 · « **Reply #19 on:** March 11, 2012, 05:57:23 PM »

there's definitely no comparison between the detuned ones and the higher output versions. My K1, running well had a lot more nuts than my friends very clean, low milage k6. I'm gathering bits to build a bit of a frankenstein, and that was why I asked the question. 754, I truly wish I were anywhere near BC, and I'd take you up on that offer.
Still, I'm wondering if anyone knows a place where there are some graphs with the various years and their power curve/rpm .
Thanks!

23tbucket · « **Reply #20 on:** March 11, 2012, 09:28:50 PM »

Hmmm around these parts...the 1976 CB750 A.....

Careful there 754...I'm not very far from you.....Na...more engines means more work....got five old running Hondas now.

BobbyR · « **Reply #21 on:** March 12, 2012, 02:34:57 PM »

Read this test report excerpt:

Honda takes up the slack with their unsurpassed engine technology: the original 1969 CB750 turned the 1/4-mile in what would now be termed a sluggish 13.5 seconds at 100 mph. Seven years and 27 pounds later, the F2 goes 12.7/105, proving that Honda R & D is a fountain of youth for paunchy middle-age motorcycles. As long as the engine well gushes forth two or three horsepower every year, people won't scream about another 20 pounds.

The whole article is here: http://legacyweb.triumf.ca/people/baartman/bike/cb750-77.html

Jerry Rxman Griffin aka MuthaF'er · « **Reply #22 on:** March 12, 2012, 03:04:34 PM »

And the 75 750F had been clocked at 12.9 in one article.

BobbyR · « **Reply #23 on:** March 12, 2012, 03:34:15 PM »

Quote from: Jerry Rxman Griffin on March 12, 2012, 03:04:34 PM

And the 75 750F had been clocked at 12.9 in one article.

Jerry, Professor TT is always espousing data. Well some people may be unhappy but the "detunig"
were refinements according to the data.

Hinomaru · « **Reply #24 on:** March 12, 2012, 03:59:17 PM »

1969 sales literature shows the quarter mile time as 12.6 with 68 horsepower ...

click on image for larger view

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Author Topic: Which year had the most HP? (Read 6227 times)

Hinomaru