Tuesday 15 February 2011

Honda CB72

A friend was buying a Honda CB250G5 (he was almost alright after the treatment) and was selling his Honda CB72. I couldn't part with the cash fast enough, sixty quid changed hands (this was when sixty quid was sixty quid) and he promised to deliver the bike the next weekend.

The bike's arrival was heralded by lots of exhaust noise. For some time we waited for the bike to appear at the bottom of our road. We waited a bit more, eventually the bike came into view, the rider and pillion paddling the tarmac like people trying to get up a hill on a bike with not a lot of clutch.

This was not surprising because they were on a bike with not a lot of clutch. Eventually, he drew level with the house and suggested that the clutch might need a little adjusting. Many phrases sprang to mind, mainly relating to questioning his intellect and/or parentage. These were stiffled in deference to his pillion, Jane. After they had gone my mate and I got down to the serious business of deciding I had been totally stitched up. This was not actually the case but I always feel I could have done better when I buy a bike.

The clutch slipped, the electric start didn't, the kickstart was running (well, flopping about) in a nylon bush, the fuel tap was leaking despite being covered with half a pound of Araldite, the black paint on the petrol tank and silver on the sidepanels rubbed off a bit too easily, the seat cover was ripped, an exhaust baffle was missing, the chain was shot and the bike needed a good bath. All in all, not too bad for a first look!

These early (1966) Hondas have rather quirky styling, a bit like an NSU of the time or an MZ of a few years ago. In fact, the Laverda 750 twin engine looks suspiciously like a grown up version of the CB72. I found out later that they are pretty solidly built with no comparison to a 1974 Honda CB360G5 I once had the misfortune to own. The petrol tank was a bit hump backed, with low flat bars and forward mounted footrests the riding position was a bit hump backed as well. The footrests were carried on neat alloy brackets which allowed a range of adjustment aided by adjustable brake and gear pedals.

There were twin leading shoe brakes front and back, an electric (non, in my case) starter and stainless steel silencers (where are they now, Honda?) with removable baffles. There were also some rather oddball items like the forward facing kickstart, awkward to use unless facing the wrong way, and the speedo and tacho both housed in a lozenge shaped unit working in opposite directions (the trick was to try to get the needles to meet in the middle). The four speed gearbox was spoilt by a quick wear rear set type linkage, the result imprecise changes. The engine could have used another ratio but you could chug along merrily enough at low revs. The yellow band on the rev counter starts at 9000 and ends at 12000rpm.

When the CB72 was introduced, it was a critical period for Honda, challenging the domination of the big British twins with machines half their size and making the British 250 singles look decidedly antiquated. Without doubt, the main plus point of the CB72 was its engine - an OHC vertical twin with the usual huge, four bearing crankshaft assembly, gear primary drive, twin carbs and a minimal need for frequent maintenance.

Perhaps, its only major failing, and one replicated year after year by the Japs, was sharing the engine and gearbox oil, a feature that demanded constant 800 mile oil changes and resulted in an inferior gearbox action to any number of British bikes. At the time, most pundits concluded that such a high revving engine would not last long, but they were mostly proved wrong by the relative absence of that real cause of mechanical mayhem, vertical twin vibes.

Clutch plates and starter clutch from the breakers and new air filters, chain and sprockets had me on the road. The handling did not inspire confidence, not helped by a square section rear Avon Deathmaster and almost worn out original front Bridgestone nylon job (with 3mm of tread left after 18000 miles it made up in longevity what it lacked in grip). The tyres allied with rear non-absorbers and front forks full of paraffin had me on my earhole several times early on. After one ride across a wet and greasy London (we called it London in those days) during which I came off three times I decided that perhaps some work was needed.

Despite what the UMG says about the handling, I think the actual frame is fairly rigid, with oil in the front forks and some Girling shocks from a breakers out back, the whole plot felt fairly stable. The tubular frame dispenses with down tubes and uses the engine as a stressed member - if you stuck some modern cycle parts on it, it could pass for a fairly up to date bit of design work.

With a bit of effort, footrest one side and centrestand the other, could be scraped sufficiently to amuse onolookers. The CB72 frame is not the same as the C72, the CB utilising more tubes where the C has mere steel pressings. Because the engine is used as a stressed member I had an unusual problem. For some time, the bike would pull to one side when accelerating and pull to the other when braking.

We eventually (we, because I needed a bit of help) traced the problem to loose engine bolts allowing the motor to twist and pull the rear wheel off line. The frame and suspension had been seen to, so it was time to replace the tyres - TT100s were whacked on the rims with the aid of tyre levers and a dustbin. These tyres were still on when the bike was sold and they had lots of life left, so tyre wear would be 10,000 plus miles, the rear wearing faster of course.

Handling was good enough to scrape things, as I said, and on fast bends there was no wandering or weaving (you know what I mean, all you 360 owners). White lines, tarmac joints, etc made the bike wriggle a bit but nothing frightening. The bike wasn't flickable, surprisingly as it wasn't heavy, you had to use a bit of force to throw it into bends (as opposed to throwing it down the road). It may have been the narrow bars, but body movement was required.

Average use would normally see between 60 and 70mpg, gentle touring would achieve as much as 80mpg but the fact that the bike displaced only 250cc meant it needed lots of revs for most of the time. The CB77, a 305cc version of the same bike, has more torque and fuel economy is pretty much the same.

I managed to get hold of an official workshop manual for the bike from a helpful dealer. The manual was useful although it was sprinkled with some rather quaint translations. Terms like leaning of the body threequarters forward, and my favourite, beware of the nutting, caused a bit of head scratching. The manual claimed that at a constant 24.8mph with the body leaning threequarters forwards the bike should do 124mpg!

Needless to say, I never found out if this was true. Top speed wasn't quoted in the manual but nose on the tank speed testing produced an indicated 98mph, maybe 90mph in real mph. Power drops off dramatically after 12000rpm. To get rapid movement you need 5000 plus revs, but the bike will chug around at lower revs happily, if rather slugishly.

In all, I think I put about 10,000 miles on the bike and it never broke down on me, but I did do a fair amount of maintenance, changing oil, cleaning oil filters, adjusting timing, tappets and camchain every other week. Most jobs were easy enough but investment in an impact driver and after that an allen screw set was well worth the money. Also, a decent ring spanner, in my case a flat hunk of iron with the correct size hole in it, is needed to get the tappet covers off. Previous owners appeared to have use a cold chisel and big hammer.

Faults I did encounter were two starter clutches breaking on me, and I didn't use the electric foot most of the time. Easy enough to cure with the correct puller for the alternator rotor. Also the kickstart shaft had ruined its bearing and been repaired by the previous owner with a plastic bodge that failed quickly but the phosphor bronze bearing I knocked in seemed to do the job.

Just before I sold the bike, the engine and gearbox were dismantled. All that was replaced were the piston rings and a selector fork in the gearbox. The lot was put back together with instant gasket and polished up. The tank and sidepanels were resprayed black - I hope it made the new owner very happy for his £165. I was looking for bigger things, and I don't mean female wrestlers, buying a Suzuki T500R that was larger and faster.

Nowadays, of course, the CB72 and 77 are collectors bikes but mine was reliable, fast enough and had a build quality much better than bikes from the seventies and early eighties. I think with these early Japs part of the quality was a certain style and I would have one again if they were still sixty quid.

Ian Smith

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I've always wanted to own one of the fabled Honda Dreams. No, not one of those late seventies abortions but the original Dream of the sixties - the CB72 or 77. Later Honda twins, by comparison, were as gray as ashes. In 1990 the dream came true, some gent in Gloucestershire had done a complete renovation of a CB72, wanted a mere £1250 for the glowing 250cc's worth of prime vertical twin meat.

The test ride revealed a loose rear end. There was some lateral play at the swinging arm end, spacers missing from the bushes. I pondered that he may've left out some spacers in the engine, which might explain the less than pristine gearbox but the rest of the motor purred with an astonishing smoothness and had no trouble revving out in second and third gears. He acted hurt when I pointed out the state of the swinging arm bearings, something immediately obvious from the saddle, suggesting he hadn't gone far afield on the bike. Despite my misgivings I definitely wanted the bike and ended up handing over the full price as he wouldn't budge on the money side of things.

There are lots of different ways of starting out on a relationship with a bike. Falling off ten minutes into my ownership was not the best of them. Swinging the 350lbs of refurbished metal into a 20mph town bend, the bike just flopped down as the adhesive abilities of the tyres failed suddenly. It's always a shock to the system to find myself violently thrown through the air. On this occasion I landed on my knee and the bike scraped up a layer of tarmac.

After the pain went away I picked up the Honda, scowled at the damage to the paint, pegs and bars and then spent five minutes cursing until it fired up on the kickstart. The rest of the journey was done at 10mph, my body needing a good night's sleep before my courage returned. A change to Avon tyres and shims in the swinging arm made sure there was no repeat of that particular accident.

The CB72 did, though, appear to be very easy to fall off. Within the month I'd hit the side of a car and knocked down a dog. Each time I was flung painfully off the Honda whilst it exacted some carnage in revenge for my slow reactions. Was it jinxed or was I just stupid? God knows, all I can say is that it got better with experience.

The car had its side ripped off by the diligent front wheel which was buckled but still rideable if bars that shook like an earthquake was going down were ignored. The dog was almost cut in two, spent fifteen minutes wailing its head off before it finally died. A bit stomach churning that but at least it hadn't damaged the rebuilt front wheel.

The way the Honda shook off these crashes convinced me that it was a very tough machine. It certainly looked butch, with the large mass of alloy engine hung from a tubular backbone frame, the cylinders canted forward aggressively. Neat touches were adjustable footrests, BMW inspired riding position and a stainless steel aftermarket exhaust system. I could've done without the leaking petrol tank cap and gearchange lever that kept coming loose on its spine.

The first time the latter happened I thought I'd bought a lemon, been ripped off with a bike that had a naff gearbox, and rode along in third for five miles before I chanced to look down to see the merely loose lever. The torque was good enough to run down to about 15mph before the chain threatened to leap off the sprockets. Spirited road work needed a lot of revving because the gaps between gearbox ratios were large. The lever needed tightening down once a week to avoid a repetition.

The clock read 49000 miles, the rebuild done at 47000, the only sign of its advanced age being the need to do 500 mile services - carbs, tensioner, valves, points and oil. To ignore its needs was to end up with a very rough running motor than would refuse to go above 8000 revs. In fine fettle as much as 95mph could be put on the clock, with 80mph cruising sitting well within the capabilities of both the motor and chassis.

The suspension was, I was told, much modified, with a fine pair of Girling shocks and an equally stiff pair of springs in the refurbished front forks, whose action - smoothness and preciseness - wouldn't have disgraced a modern machine. Cornering was limited only by the willingness of the stands to dig in and an unsettling feeling from the tyres which would squirm under extreme abuse and play games with whitelines even under moderate use. Strange, because the same tyres on another bike performed magnificently, so probably down to some quirk of the CB72's steering geometry or weight distribution.

There was also an element of poor design in the final transmission, although to be fair to the old Jap primary transmission was through a set of gears whose precision of engineering would've sent the British motorcycle industry bankrupt if they ever had the wit to try to emulate it. Even when I bought a new chain it was a constant source of irritation, sometimes too loose, sometimes too tight; either way causing the gearchange to go very vague and amplify the low speed lurching until there was so much clutch slip involved that I could smell the plates burning to a cinder. They were probably pattern rubbish, as the new Honda plates I fitted made the clutch much more robust.

However, the engine would become quite hot after extended town riding, turning the gearbox wicked and causing the clutch to drag. As neutral became impossible to find I ended up stalling the CB at junctions as it would creep forward under the influence of the drag until I had to hit the brake. It would also bind up over night so that when first was engaged it did so with a milk bottle shattering detonation that stalled the mill dead.

Starting was always finicky with a touchy choke and need for newish spark plugs, taking a good ten minutes to warm up. Surprising were the lack of rattles and low tickover speed once the oil had a chance to warm up and circulate - as in all old Hondas, blipping the throttle of a cold engine would lead to written off camshaft bearings, as would neglecting the frequent oil changes.

On any bike almost thirty years old there are going to be lots of minor hassles but the CB72 was one of those machines that endeared itself the more it was ridden and unlike British relics of a similar era there were no worries about a disintegrating engine even when the throttle was heavily abused - its pure engineering quality shone through and it was easy to see how Honda was eventually going to take over the motorcycle world.

In a year I did 7000 miles, insufficient to dent the consumables but no reason to suspect, chain apart, that they were going to be anything other than long lived. Fuel ranged from 60 to 70mpg and oil neither burnt off nor leaked away. Overall performance was better than a 250 Superdream, as shown by the many times I burnt off such machines, a trick their riders singularly failed to appreciate. Cagers were equally outraged to be put in their place by such an aged machine, but there was little they could do about its whippet-like performance, especially in traffic where its overall narrowness and confidence inspiring TLS drum brake made for some real madness. Alas, money problems caused me to sell the CB, but I made sure it went to a good home; least I could do!

Jay Goodge