Saturday 2 July 2016

Honda CB750K


The throttle was jammed open in third gear. The redline was past news. the speedo needle was quivering around the ton, the bars and footreets were thrumming nicely, the weave was tolerable, the clip-ens allowed me to get my head down by the instruments and the rearsets Ievered my body into a forward crouch that the naked machine allowed to take the full windblast.

Whenever l ventured above the ton I always had qualms. If something went wrong there was so little time to react before disaster struck. I was always aware of just how old and worn were most of the bike's components, having 74000 miles under its wing. Just one bit of metal failing and it could be goodbye yours truly.

That didn’t stop me doing a clutchless change up through the box to fourth. The bike lurched into the new gear, a slight mechanical whine not quite lost in the wind added to my worries. I knew I had to get 120mph up to stand a chance of reaching top speed in fifth.

The bike was still on the original bores and pistons. the single overhead camshaft top and had only been attended to by addition of a new camchain and tensioner. so power was hard to find at that kind of speed and acceleration stately rather than fierce.

The route was along a wide, straight, smooth A road, the time was just past 6am and it was deserted of all other vehicles. This was just as well. Past 110mph the weave degenerates into a wobble, not even tightened up forks and Girling shocks can combat the lack of rigidity in the tubular steel frame and swinging arm. In the seventies Honda knew very little about the secrets of making bikes handle.

By 120mph it's taking up most of the road in its series of periodic weaves and wobbles, my backside and arms are getting a battering trying to hold the beast on some sort of set course, whilst the petrol tank has started thrumming between my legs. Still, I keep at it, up to top gear, no clutch and the throttle kept wrapped open... it had taken me two years to get used to the knackered gearchange action and develop enough feel to avoid the multitude of false neutrals between the gears. Most old Hondas are so bad that if the bike is given to a friend for a spin chances are they’ll find it impossible to ride!

130mph on the clock, still not enough for me, I want that elusive extra 10mph. The end of the straight is in sight, so that's the end of that idea. The Honda will only go around the curve at 60mph, so I have to wrench on the single front disc, a device of puny effect and totally lacking in feel by today's standards, and try to stabilise the bike using the rear drum. Down past 100mph reasonably quickly, a flick of the foot and some clutch action to get into a gear where engine braking will help. Then the dreaded speed wobble hits as the speedo touches 90mph.

 

Some clever Trevor might advocate taking hands off the bars when encountering a full tilt speed wobble but not this kid. Application of massive braking effort and muscular input saw the plot back on line, but not before it had been flung so far over to the other side of the road that the back wheel had a frightening skirmish with some gravel.

This at least put me in the right place to take the corner, entering too rapidly at 75mph, still braking, but ever so gently, to scrub off some more speed. Most of the things that used to touch down (stands, exhaust, pegs) have been junked or modified, so I had no qualms about hurling the beast over.

The Avon Roadrunner tyres gripped well on dry roads, it was just that if the machine hit a bump or was braked too harshly the whole bike turned into a bouncing blancmange. Not this time, I had even contrived to get it in the right gear for an accelerative exit up the next straight. I have ridden modern race replicas that would have done the last straight at 150mph and gone around the corner at 90mph as if on rails, but to me they were just too easy to ride. There was nothing quite like battling with an old Honda 750 four, thrashing the machine to get the most out of her, fighting the chassis and elements all the way.

I could also cope with the Honda mechanically. These days it can only be described as a paragon of design simplicity and there is little that I can't fix in my own workshop. l have had the bike for the past 50,000 miles and apart from the camchain have only had to replace the clutch (the whole unit was well shagged out and a used one off a later model was fitted, being a lot less rattly).

Maintenance, too, was not a great problem. although it was time consuming and frequent. Unless the bike was attended to every 2000 miles it became very ratty indeed. The valve clearances always needed attention, the camchain tensioner a tweak, the carbs balanced and the points gap checked.

The quickest I ever managed for a full engine service was two hours. more often it took twice that. It should go without saying that the oil was changed every 1000 miles. if the engine was out of tune it became particularly difficult to pilot through town. The engine backfired and occasionally stalled.

As the electric start had failed at 62000 miles this proved very embarrassing at times, although to be fair, at least it still had a usable kickstart. At the best of times, endemic clutch drag made town riding less than pleasant. Neutral was almost impossible to find at a standstill and the front brake had to be applied to stop the bike crawling forward if it was in gear. From a cold start first had to be engaged with the front brake held on to avoid a nasty crunching noise and a stalled engine from chronic clutch drag.

Once the motor became all hot and bothered from excessive town crawling, tickover varied between 1000 and 3000rpm, gears crunched into place and the bike generally played up like some temperamental Ducati single that had strayed off the race track. With the clip-ons fitted it required a tiring amount of muscle to fling out of the path of psychopathic taxi and bus drivers, whilst the width of the engine. with the alternator perched precariously out in the wind, precluded high speed filtering between traffic stalled autos.

Motorway cruising was not particularly pleasant, either. With the modified riding position the machine could’ve maintained a 90mph cruising speed (barely adequate to keep up with autos) had not the vagaries of the chassis meant that at such speed it needed more than one lane of the motorway to career around in. 70mph was much more stable, 80mph possible as long as a, great deal of steering precision 1 was not called for.
 

Acceleration from 80mph to the ton in top gear was adequate for getting out of tricky situations if not particularly arm wrenching in effect. Top gear could, in fact, be used from 40mph onwards with sufficient torque available to avoid the necessity of indulging in the terrifying prospect of changing down the box.

An annoying level of vibration crept in at around 55mph, disappeared once past 60mph only to reappear all the more fierce after 90mph. If you've ever owned a ratty Bonnie you would not bother to complain about it and the vibes do little damage to any of the machine’s components. No, the joys of this machine are to be exploited on fast A roads, where much abuse of the steering and gearbox result in a wide, if at times terrified grin.

One of my greatest pleasures is scaring the shit out of some race replica Rodney by shooting around the outside of him on the bouncing and buckling Honda, throttle held open in disdain of the other machine’s superior chassis. Yes, a trifle wild but I’ve yet to eat tarmac!

Problems with the Honda? Well, it's had three calipers as they seize up something chronic (the disc brake is terror inspiring in the wet as it lags and then locks up solid). Two sets of coils have failed, one regulator burnt out and nearly turned the bike into a blazing inferno. I've had batteries that have only lasted eight months! The guards have rusted right through twice despite preventive measures and the seat fell apart. I’ve had the sidepanels nicked twice! One back wheel broke half a dozen spokes, the replacement went through its bearings in 2500 miles.

Pretty much what you'd expect from a twenty year old bike slowly making its way around the clock. I did have it resprayed throughout, so it looks pretty good now and the engine alloy still shines up with Solvol. I occasionally meet the odd old buffer who goes on about what a great investment they are but they soon piss off when I mention how easy it is to get past the redline and how the handling goes to pot above the ton. I may well buy a newer bike, but I aim to keep the CB750 running for as long as possible.

Greg Williams