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Honda CB 750 Four K4

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Make Model

Honda CB 750 Four K4

Year

1974

Engine

Four stroke, transverse four cylinder, SOHC, 2 valve per cylinder.

Capacity

736 cc / 44.9 cub in.

Bore x Stroke

61 х 63 mm

Compression Ratio

9.0:1

Cooling System

Air cooled

Lubrication

Dry sump

Induction

4 x 28 mm Keihin carburetors

Ignition

Battery, ignition coil

Spark Plug

NGK D8ES-L, NDX 24 ES

Starting

Electric, kick

Max Power

50 kW / 67 hp @ 8000 rpm

Max Torque 44 lb-ft / 60 Nm @ 7000 rpm

Clutch

Multi-plate, wet

Transmission

5 Speed

Final Drive

Chain

Gear Ratios

1st 13.99 / 2nd  9.54 / 3rd 7.45 / 4th 6.14 / 5th 5.26:1

Frame

Tubular steel duplex cradle

Front Suspension

Telescopic forks non adjustable.

Front Wheel Travel

143 mm / 5.6 in.

Rear Suspension

Swingarm, dual shocks, preload adjustable.

Rear Wheel Travel

85 mm / 3.3 in.

Front Brake Single 296 mm disc
Rear Brake 179 mm Drum
Front Tyre 3.25-19

Rear Tyre

4.00-18

Rake

27°

Trail

95 mm / 3.7 in

Dimensions

Length: 2175 mm / 85.6 in.
Width: 870 mm / 34.3 in.
Height: 1170 mm / 46.1 in.

Wheelbase

1453 mm / 57.2 in.

Seat Height

810 mm / 31.9 in.

Ground Clearance

140 mm / 5.5 in.

Wet Weight

218 kg / 479 lbs

Fuel Capacity 

17 Litres / 4.5 US gal

Reserve

5 L / 1.3 US gal

Oil Capacity 

3.5 L / 3.7 US quarts

Consumption Average

6.9 L/100 km / 14.6 km/l / 34.3 US mpg

Braking Distance 48 km/h / 30 mph - 0

10 m / 32.9 ft

Braking Distance 97 km/h / 60 mph - 0

41 m / 135.7 ft

Standing ¼ Mile  

13.5 sec / 100.9 mph

Top Speed

198 km/h / 123.2 mph

Colours

Flake sunrise orange, Freedom green metallic, or Boss maroon metallic

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The CB750K4 Four was sold in 1974 and was available in one of three colors: Flake Sunrise Orange, Freedom Green Metallic, or Boss Maroon Metallic. The gas tank stripes were white, gold and black. The side covers were smaller than the K0 model and there were no slots on the leading edge. The speedometer showed increments of 20 (i.e., 20, 40, 60, 80, etc.). The upper forks were chrome. The white tank pinstripe was wider than the K3 model. The headlight shell was black. The taillight and side reflectors were larger than the K1 model. There was a two-throttle cable system (pull open and pull closed). The exhaust system was a 4-into-4. The engine was a 736cc SOHC 2-valve dry sump inline 4 cylinder linked to a 5-speed transmission and chain drive. The serial number began CB750-2300001.

 

 

It is no exaggeration to say the Honda CB750 is the most significant motorcycle ever made and altered the world of motorcycling forever. Prior to the CB750 you had two choices in motorcycles: You could have a small, reliable Japanese bike or you could have a larger, faster but unreliable bike. The CB750 proved to the doubters that the Japanese could build a large bike (a 750 was considered monster-size in those days.) It was the first to come standard with a hydraulic disk brake. It had both electric and kick start. It started every time, parts didn't fall off and it didn't leak oil. We take these things for granted today but it really meant something in 1970!

It wasn't all about practical everyday driving either. The CB750 was equally at home on the racetrack. A modified CB750 won the 1970 Daytona and set a new track record. The world took notice.

The British motorcycle industry, notorious for unreliable motorcycles and already on the ropes, was finally put out of their misery. This bike and its successors very nearly put Harley-Davidson out of business too. The CB750 raised the bar in the industry. You had to either improve your designs or get out of the motorcycle business.

Honda built about a million of the CB750s over its ten year history. To get a feel for how popular that is consider that BMW, which has been making motorcycles far longer than Honda, only recently rolled its millionth bike off the assembly line.

I was only five years old when the CB750 first appeared so I was too young to understand its importance. The CB750 was a common "college" bike when I was in school. They were reliable, plentiful and cheap. You could keep those bikes going forever. I bought this bike to relive those times and see if a twenty-seven year old bike could still compare to a modern machine.

My 1974 CB750 came from a collector who had partially restored it. It is in excellent mechanical condition, very good cosmetic condition and the mileage is low (13,000 miles when purchased.) It's a good candidate to compare to modern motorcycles. My girlfriend has named her "Pumpkin" for her bright orange color.

On to the good stuff. How is it to ride? The short answer is it is still fun to ride today. No, Pumpkin can't match modern motorcycles in many ways but the differences are not annoying and there is a certain special satisfaction when riding a bike that is a part of history.



The differences become pronounced once you start to push the bike and feel around the edges. The CB750 is much heavier than modern bikes and perhaps more important it carries its weight high. You have to keep this in mind when corning at speed but it generally doesn't get in the way. The single disk brake with its one piston caliper was the marvel of its day but pales in insignificance compared to something like the antilock power brakes on my BMW R1150RT. The right attitude for any bike of this vintage is to think of the brakes as something that slow you down rather than stop you.

Acceleration is quick and torque is adequate at high revs as you would expect in an inline four. She can keep up with modern sport bikes in the straights although the handling is inferior in the curves.

The engine takes a few minutes to warm up before it's happy. This is still true today with modern inline fours but computer controlled ignition and fuel injection take all the fun out of it. You have to adjust the idle level and there never really is anything like keeping it spot on. After riding at high speed for several minutes the engine reaches its maximum normal operating temperature and you will notice the idle creeping up to 2,000 rpm. Just live with it or get used to reaching behind the carbs and adjusting the idle screw with your left hand. Careful not to burn yourself!

The petcock is oddly on the right side of the frame. What happens when you're riding and have to switch to reserve? The only safe thing to do is pull over to turn the petcock.

But these are nothing more than little quirks that give the bike its character. Pumpkin is still every bit as competent a street bike as she was in 1974 and none of the pleasure has faded.

There is a reassuring feeling about having the kickstart on the bike. Honda felt that customers weren't ready to trust an electric starter so they included one. Pumpkin starts on the first or second kick when warm. I haven't tried to kickstart her when cold.

I'm glad to have her. Despite her age she still puts a smile on my face and that is, after all, the final test.