New Life for a 1971 Honda CB450 K4

A missing bushing goes undetected for years but makes a big difference

| July/August 2007

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.

6/17/2012 12:46:27 PM

I bought a very nice 1972 CB450 while I was going to college in the mid 70's. It felt like a big bike to me since I'd only owned an SL125 up to that point. My roomate had a CL350 that I'd ridden several times and the differences between our bikes were substantial. We rode all over Central Illinois, on black-topped country roads mostly, and I remember that the Hondas of that era had a very distinctive sound (probably a result of the chain driven DOHC design). My 450 was a torquey little beast and proved to be a reliable mount until I sold it and moved up to a Yamaha XS 650. As is the case with most of my bikes I wish I had it in the garage today...

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