Topic: This maybe a stupid question

[scamper03]

Hi, 

I have 78 cb750k and I had it over 2 years.  I love riding it and I think it runs pretty good.  My question is I had a sports bike prior to getting my CB750 and I am assuming that the performance of my 31 year old bike isn't going to be same as the modern day sports bike. I am just trying to understand if my bike is running as good as it can be since I don't have any previous experience riding an older bike. 

Thanks

[MCRider]

Not a stupid question...not really a question at all.   

[Simpson]

There are no question marks. 
I think you are hoping for some feedback on SOHC performance.
Maybe you could describe your performance.

[scamper03]

You're right.  I guess I am just not sure if my bike is running the way it supposed to.  I am used to the torque of the sports bike I had and my CB750 isn't like that.  It rides pretty fast once I get it up to higher gear but it's nothing like a sports bike.  Evertyhing I read about cb750 says it was the orginal superbike so I guess I am trying to understand the kind of expectations I should have for the bike.

I am not sure if my 1st and 2nd gear has enough torque. 

[Simpson]

Here's mine when I first got it running. I'm not sure what you mean by sport bikes but most modern liter bikes easily put out over 130-200 hp, these things are probably under 60 hp to the road on a 550 pound dry weight. 40 years ago, that was a lot.

[MCRider]

Yeah, to say its the first Superbike, well... we need perspective. The Cb750s put out 50 to maybe 75 HP depending on year and model, I'm not sure where yours lands in that range, but I'd guess no more than 65.

A modern CBR600 puts out 100+ hp, and more torque than the CB throughout its range as well. And has a 6 sp trans to spread it out. And is lighter, etc.

Don't know what your sportbike was, but the CBRs have been doing that for many years, pre 2000 I'm fairly sure. Other makes and years put out more.

You need to do your full tuneup, attn to details, etc. but keep the aforesaid in mind.

So the CB750 will get you a good speeding ticket and will still kill you just as dead if you do something stupid. But as far as power compared to modern post 1990 sport bikes, its a slug. A happy, satisfying, loveable slug.  

[Simpson]

I love my slug. 

[cookindaddy]

Me too! I guess I better not ride a newer bike?!
I feel like I have more than enough power on my 78 750K to kill myself REALLY easily. But then, I am older than I was and my reactions aren't what they used to be.

[scamper03]

Thanks guys.  That helps me out a lot.  I had a ninja 600 so that's what I was comparing it to.  My cb is 78 and it is pretty fast like I said once I get it up to the higher gears.  I wasn't sure if it is supposed to pull like the moder day bikes but now I know. 

[Simpson]

I'm always chasing sport bikes with mine for grins. I'm like a dog chasing passing cars.

[nobody]

I love to play with modern bikes on mine but I never have expectations of beating them. Even if I'm working it through some twisties, that modern bike will just pass me in full cruise mode.

[TwoTired]

An old magazine performance report said the CB550 did the quarter mile in 14.02 sec.
  I know the 750 was faster.  Maybe by .5 or even a second better.

So, mark off a 1/4 mile somewhere safe.  Wail on the bike and see what you get.  If you get 15s you're either a crummy shifter, a 350 pounder, or something ain't right with the bike. 

Cheers,

[CrankyOldGuy]

Back in 1971 when I purchased my K1 my two biking buddies had a Kawasaki 500 and a Norton 750 Commando.  The Kawasaki was a crotch rocket which took on a life of its own at 4000 rpm, the Norton was a workhorse who could vibrate you to death , and the K1 ... well was the queen ... smooth, reliable and fast.  Cruising at speeds of up to 100 mph were almost unheard of before.  In fact we were stopped once by the RCMP ... not to receive a speeding ticket ... but because they had never seen anything like them before.   The 750 in my opinion was the motorcycle before its time ... the disc brake proved that for me a few times   Boy to be 18 again 

[MCRider]

Back in 1971 when I purchased my K1 my two biking buddies had a Kawasaki 500 and a Norton 750 Commando.  The Kawasaki was a crotch rocket which took on a life of its own at 4000 rpm, the Norton was a workhorse who could vibrate you to death , and the K1 ... well was the queen ... smooth, reliable and fast.  Cruising at speeds of up to 100 mph were almost unheard of before.  In fact we were stopped once by the RCMP ... not to receive a speeding ticket ... but because they had never seen anything like them before.   The 750 in my opinion was the motorcycle before its time ... the disc brake proved that for me a few times   Boy to be 18 again  

At 16/17 (1970) the first bike I owned was a 67 Triumph Bonneville. At that time a twin Bonnie powered streamliner held the Land Speed Record. My Bonny was plenty fast. When i took it for a tour of the west, I set out thinking I could cruise at 70mph, certainly within its reach. But the vibrations just killed me and within a few hundred miles I settled into a sweet spot around 55mph. I finished a 6000 mile trip hardly ever going faster.

Soon after I got my K1 (grass cutting money) and the world was redefined. True 70mph+ cruising, 5 speeds, disk brakes, etc. It was a quantum leap, the first "real" superbike. Where performance and human accceptability (not simply tolerance)  came together.

I loved all my CBs even when the faster things came along. I'll love it again when I get it back on the road. But the difference between it and my mighty FJR is another quantum leap...or three.  

[Simpson]

This weekend I went on a 2up day of riding with full saddles and top case over 200 miles. We cruised reasonably comfortable between 55-80 mph (mostly 70) and reaching 85 a couple times on the hwy. It was a great day.

[dhall57]

An old magazine performance report said the CB550 did the quarter mile in 14.02 sec.
  I know the 750 was faster.  Maybe by .5 or even a second better.

So, mark off a 1/4 mile somewhere safe.  Wail on the bike and see what you get.  If you get 15s you're either a crummy shifter, a 350 pounder, or something ain't right with the bike. 

Cheers,

I remember reading a motorcycle mag back in the 70's on a CB 750 road test, don't know what year it was, but in the 1/4 mile it was turning in the low 13's at about 100 mph. At the time the only bike on the market that was faster was a Kaw triple 2 stroke which was running high 12's.

[going4speed]

The test I read said a 12.74 in the quarter mile.  Plenty fast for the street and will leave 95% of cars in the dust. 

An old magazine performance report said the CB550 did the quarter mile in 14.02 sec.
  I know the 750 was faster.  Maybe by .5 or even a second better.

So, mark off a 1/4 mile somewhere safe.  Wail on the bike and see what you get.  If you get 15s you're either a crummy shifter, a 350 pounder, or something ain't right with the bike. 

Cheers,

[Don R]

Most of those mag tests were done by Pee Wee Gleason, he could make anything faster just by riding it!