In my travels I came across a red 1971 scrambler version! It may seem a little insane to consider going off-road on a bike like the CB450, but such styling exercises were all the rage in the States back then. Basically, it was a stock CB450K with a smaller tank, high bars and high-rise exhaust system. Much more of a road bike than trailster, perhaps capable of the odd spin on gravel when a desperate urge arose.
The bike was basically intact but rather tatty around the edges - lacerated seat, dented tank, rusty exhaust, worn out knobblies, frayed cables, loose swinging arm bearings. But the motor fired up on the electric boot, sounded remarkably quiet at tickover (always a good sign) and didn’t spit out any smoke (check the breather as well). Mine for 750 notes and a wicked smile from the dealer that seemed to indicate I'd just been done.
He delivered the bike to the humble squat, the presence of half a dozen roaming wolves (well, big dogs but they looked indistinguishable to me) soon took the grin off his face. The bike was hauled up into the house and fixed up over the next couple of weeks.
It's dead easy to leap on a CB450, toddle off around the block and conclude that it’s a bit of an old monster. It has a massive four bearing, 180° crank, with pistons that move up and down alternatively. This gives perfect primary balance (unlike the old Brit designs) but there's a torque reaction along the length of the crank. This is rather like big BMW boxers, insofar that the engine shakes away for the first few thousand revs.
Come 6000 revs, power pours in and the motor smooths out to a degree where it's quite happy cruising at 9000rpm! The bike was quite amiable at lower revs, with a surprising amount of torque. This upside down nature of the engine must’ve confused the hell out of old Brit twin riders in days of yore!
Incidentally, and somewhat conversely, with the carbs balanced perfectly and a decent set of plugs, it'll happily tickover at 600 revs with an amazing lack of engine noise. Part of that must be down to the superior design of the cylinder head. DOHC’s work rockers that sit on eccentric spindles for adjustment (the screws easily accessible on the side of the engine) whilst the normal valves were junked in favour of torsion bar springs which act on the valves via yet more rockers.
This is a complex and expensive way of allowing engines to rev high whilst minimising the actual moving masses in the valvegear. All sets of rockers and torsion bars are matched and if they get mixed up it results in dropped valves. Honda didn’t incorporate this into their other designs (CB500T apart) because valve spring technology moved on (and wasn’t so stressed in four cylinder designs) and the sheer expense of it made it less than viable.
But there’s no reason to consider the CB450’s top end as anything other than excellent. I found that I could string third gear out to 12000 revs without it feeling like it was about to explode. The engine was never sedate nor remote. Every twist of the throttle resulted in a change of exhaust note and alteration in the way the motor, er, thrummed! The weird thing was that after a couple of weeks the vibration disappeared completely.
It was only when leaping on to a more modern machine that I was astounded by the new levels of both smoothness and chassis sophistication. If you like your bikes a bit rough and ready the CB450 will appeal, if you want smoothness to the point of blandness, look elsewhere.
As with the vibration, first impressions of the handling were of top heaviness but this soon faded, replaced with a useful amount of feedback from the tarmac (springing was taut enough to suggest an upgrade) and, dare I say it, a security in the ride that had me flicking it around with more abandonment than many a modern bike!
Of course, whilst the power was always meaty and brutal it was only, at the end of the day, forty or so horses. This stressed the relatively modern Avons not one jot, allowed me to push along at extremes that would have modern bikes tied up in knots due to the sheer excess of goodies at the end of the throttle cable. Wheelies, wheelspins, etc., were entirely foreign to the CB450 - indeed, more likely to break the clutch or gearbox than achieve interesting forward motion.
If there was one area.in which the bike showed its age it was the transmission. A five speed gearbox that had not taken 26000 miles of abuse at all well. What can you say about old Honda gearboxes? Crap just about sums it up. It took me two months to really get to grips with the box, and then only by starting off in second whenever possible because getting from first to.there was close to impossible without becoming stuck in neutral.
Even when I re-learnt the tap dancing lessons of my youth, the clutch was also prone to overheating in town. The plates dragged, the bike threatening to move forward until | had to apply the brake, which stalled the engine. Adjusting the clutch play at the lever helped, as long as I didn’t forget to loosen it back off when the motor had cooled down again!
The clutch pushrod seal sits next to the drive chain, gets covered in crud and lasts a mere matter of months, before half a sump’s worth of oil leaks out. It can be pulled out with a screwdriver and replaced without splitting the engine (the seals are readily available in bearing factors, buy two because it’s a bit of a job to get the new one back in straight).
I also had the chain (far from new as it was) snap on me at low speed. It can often bend the clutch pushrod and sometimes cracks the crankcases. Neither of those happened to me, | just had a three mile push back to base. The tiny engine sprocket doesn’t help chain longevity but basically it’s the same stuff they use on the 250, and therefore barely adequate. Old style chains are a messy business that will bring tears to the eyes of anyone used to modern, almost maintenance free, O-ring jobs.
As will the maintenance requirements of old, worn Hondas. We're talking 500 miles here - oil, valves, carbs, camchain tensioner and points. I even found the starting went off if the plugs weren't replaced (though it’s an easy job as there’s nothing in the way). The valve clearances are very fine and finicky to set despite the screws being external. I’ve got it down to about an hour for the four of them.
Maybe I’m just incompetent, but every time I tightened up the locknuts I couldn't stop the clearances closing up, so had to take this into account. If valve clearances are neglected the valves end up burning out! If you want an easy life give this bike a miss. Neglect of oil changes isn’t possible because the gear change gives up once the lube degenerates past a certain point. There's also a filter on the end of the crank that should be cleaned from time to time but needs a special tool to extract it. I didn’t have it so it didn’t get done. I relied, instead, on the magnetic sump plug to pick up any odd bits of swarf floating around!
By the way, such is the frequency of oil changes that it’s dead easy to round off the sump plug worth checking because if it has gone that far it's likely that oil changes have been neglected. About the only good thing that can be said on this front is that even when thrashed the sump level never seemed to fall between lube changes.
Having adapted to all these needs, and become used to its idiosyncrasies, I have to admit that I found riding around on the Honda great fun! Not least because it was a bit of a street sleeper. Some poor guy on a modern bike clocking it as a rat CB500T, suddenly had the shock of his life as the bike roared off at 10000 revs, a lovely, milk bottle shattering, howl out of the exhaust. OK, once they got to grip with things, they would howl past on one wheel but I’d soon catch them up again in town, as the Honda was narrow and could be flicked every which way through the traffic.
Cut and thrust was limited only by the front TLS drum brake. This wasn’t the antique its appearance might suggest, was in fact quite powerful, highly progressive and a dream in the wet. The only hassle was that a few really hard stops made it overheat and then fade badly. Not total suicide as there was masses of engine braking and useful back-up from the rear drum, but it did mean I had to ride slower than the bike was capable of until the brake cooled down a little.
For the money, and considering the bike’s age, I can't really complain about the Honda. It must have been a shocker back in the sixties and can even show modern bikes a thing or two (like 65mpg despite been ridden hard and usable handling despite weighing 400lbs). Having said all that, at this kind of age a large amount of luck’s needed to find one at a reasonable price. But worth the effort!
Dick Lewis