New Life for a 1971 Honda CB450 K4

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The CB450 carries its weight up high, making the bike look and feel bigger than it really is. Conservative styling aside, there's no denying the CB450's great classic looks.
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Conservative styling aside, there’s no denying the CB450’s great classic looks.
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Charlie O’Hanlon outside his San Francisco shop.
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Early CB450s gained the moniker “Black Bomber” thanks to their menacing black paint. This example dates to 1967.
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Honda made sure everyone knew the CB450 carried a twin-cam engine, broadcasting the fact on the bike’s side panels.

Honda CB450 K4
Years produced:
U.S. sales: 73,000 (American Honda)
Claimed power: 43hp @ 8,500rpm (45hp @ 9,000rpm 1968-on)
Top speed: 95mph
Engine type: 444cc double-overheard cam, air-cooled parallel twin
Weight (dry): 195.5kg (430lb)
Price then: $1,050 (approx.)
Price now: $1,500-$3,000
MPG: 40-45mpg

For the better part of 50 years, the words “Honda” and “quality” have gone together like bread and butter. From the beginning, Honda knew that rigid quality control was critical to success. So imagine vintage motorcycle restorer Charlie O’Hanlon’s surprise when he opened up this 1971 Honda CB450 K4 and discovered it was missing parts the day it left the factory.

Years ago, the original owner of this bike dropped it off at Charlie’s San Francisco vintage motorcycle restoration shop, Charlie’s Place, complaining about a poorly-shifting transmission. Charlie gave it a going over, and when he sent it back out on the road the transmission seemed to work properly. Some time later a new owner turned up with the bike, frustrated because he couldn’t get first or second gear to engage. It was an otherwise nice looking and low mileage machine, but the owner couldn’t afford to have the transmission taken apart, so Charlie offered to buy the bike from him. Five years went by, and the CB450 gathered dust in the back of Charlie’s shop.

Not too long ago, Bob Lee turned up at Charlie’s Place, dragging along an early Seventies CB450 he had bought on eBay as a restoration project. As these things too often go, the bike wasn’t worth restoring: “It was rusted garbage,” Charlie recalls. “I showed this bike to Bob and we worked out a deal. I took the eBay bike and gave Bob a credit for the few things I could use off it, then sold Bob this bike with the agreement that I would fix it for him. He didn’t want a full bore concours restoration, so we agreed on a ‘restoration in moderation’ with performance upgrades.”

Inside the CB450
After Charlie and Bob worked out the details of what was to be done to this CB450, Charlie started tearing down the engine and transmission. “I took apart the transmission and got a real surprise,” Charlie recalls. “First gear rides on a shaft, and there’s supposed to be a bronze bushing in the center of the gear to keep it aligned. When I took the transmission apart, the bushing wasn’t there — I couldn’t believe it. Remember, this was a low mileage bike and the transmission had never been opened up before. It must have been made the day after a major holiday.”

After that little surprise, Charlie stripped the engine down, cleaning the cases thoroughly and checking all the internal parts to make sure they were within specification. He found that most of the engine was in good shape, and figures that’s because the Honda’s owners had so much trouble with the transmission the bike didn’t see much use. Going back together, Charlie replaced all of the gaskets, the piston rings, installed a new cam chain and freshened up the cylinder head. Bob wanted the bike to be a rider, and agreed with Charlie that it should be unobtrusively upgraded. The stock ignition points went into the parts bin, to be replaced by a modified Dyna S electronic ignition, using brackets Charlie makes for the installation. Another improvement to the stock electrical system was a later model Honda voltage regulator/rectifier unit. “It really improves battery charging,” Charlie says.

When new, the CB450 didn’t have the best reputation for handling, due partly to the top-heavy engine but in larger part to pedestrian tires and inadequate swingarm and steering head bearings. New Metzler tires increase grip and cornering, and Charlie installed tapered steering head bearings to tighten up the front end, and a bronze one-piece bushing to eliminate play in the rear. “The original was a two-piece steel and plastic number that wasn’t good,” Charlie says. A braided steel brake line increases stopping power up front, but a black vinyl coating gives the line that stock look.

Riding the CB450
Charlie extensively tests each restoration before it’s delivered to the customer. “It handles much better than stock,” Charlie says, obviously pleased with the results. “The new tires and the bushings and bearings really made a difference. It does very well, even on tight, twisty roads. It’s a little top-heavy and there is some vibration that you feel when the bike hits 35mph, but after 50mph it smooths out. It cruises nicely at 55 to 65mph. But this is an old bike, after all. You don’t beat the crap out of it — there’s no point. At the time, Honda said the top speed was 95mph, and you can get close to that for short bursts. It’s lots of fun and an enjoyable ride.”

Felicity More, our test rider, owns a 1965 Honda Dream and a 1989 Honda Hawk. “I rode the CB450 around the hills in San Francisco. I’m 5ft 3in, so I was tip toes on the seat and the bike felt a little top heavy, but it smoothed out once I got going. It has a nice, comfortable upright riding position. Vibration was minimal at the moderate speeds I was riding, and the brakes are good — much better than the brakes on the Dream. And the 450 handles well — it handled better the faster I went. It’s nice for a Sunday cruiser, I think someone who just wants to cruise around and not race would really like this bike.”

So what about that original transmission? Charlie had a used transmission cluster from the same year and model CB450 in good condition, and instead of going to the trouble of testing the parts of the original transmission to see if any had been damaged, he opted to remove the guts from the original and replace them with the ones he had. The components of the original transmission are still around, though: Charlie creates sculptures in his spare time from unusable Honda parts, and he recycled the transmission into his art.

Before Honda started selling motorcycles in the U.S., the company sought out dealers with a positive image, and dealerships were set up in sporting goods and hardware stores. In 1959, their first year, Honda sold 1,732 bikes. By the end of 1960, there were 74 U.S. Honda dealers.

Early advertising never referred to Honda products as “motorcycles” — They were always “Hondas,” a fact that led to some amusing incidents. Bob Markey, a Honda dealer since 1960, tells of a woman who called his dealership back in the early days. She told him her husband and son were on their way to buy a “Honda,” and that is what they are to get. “Don’t you DARE sell them a motorcycle,” she threatened.

CB450 beginnings
Before the CB450, Honda’s biggest engine was a 305cc twin. As the baby-boom generation blossomed into teenagers, they demanded bigger and faster motorcycles, and with the increasing acceptance of Hondas in Europe and America, the time was right to introduce larger capacity bikes.

In 1964, Honda started testing a 444cc twin. This new, bigger bike had features that were rarely seen outside of a racetrack. Its dual overhead cams were chain driven, and instead of conventional valve springs the new twin had torsion bars; short, stiff pieces of spring steel splined into a tubular guide. Dual, constant-velocity carburetors fed the short-stroke combustion chambers, and the lower end rode on four caged roller main bearings.

At first, the bike came in only one color scheme — chrome and black. A period advertising campaign nicknamed the Honda CB450 “The Black Bomber,” and crowed, “A heavyweight featuring the technical advancements and outstanding performance you expect from Honda.”

 The CB450 was, in fact, a heavyweight — at 412lb dry it was heavier than the contemporary 650cc Triumph T120, which weighed in under 400lb wet. It also didn’t handle that well, although it was clocked up to 101mph in a period test. However, the average rider of the time was more interested in oil-tight cases, minimal maintenance, bright lights and a working electric starter, and the Bomber sold well.

A scrambler model, with high pipes, 9:1 compression and three color options was added in 1967. For 1968 the Black Bomber gained a fifth gear and a bigger oil pump. Power increased from 43hp to 45hp at 9,000rpm, and a new frame increased the wheelbase to 54.3in from 53in. In addition to black, buyers had the option of candy red or candy blue.

1969 was also the first year for the Honda CB750, the first Japanese made, large capacity inline four, and the CB450 quickly came to be seen at the 750’s little brother. A front disc brake was added in 1970, and after that the CB450 received largely cosmetic changes until it was replaced with the CB500T in 1975. MC

Read more about the motorcycles mentioned in this article:
Honda CB450: The Black Bomber
Honda CB750 Four: A Classic for the Masses

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