Monday 18 January 2021

Honda CB400 Superdream

The road was one those old style single laners - there was just enough room for two buses to pass by each other. The longest straight lasted for about half a mile. The bends were mostly a series of sharp twists. Ideal country for a Honda CB400N, except that there were too many cars in the way. They insisted on bunching up in twelve or so car queues, some jerk creeping along at the front or an even greater fool towing a wobbling caravan. Hotshot Capri owners would edge out onto the wrong side of the toad, then jerk back into line when they realised they were going to be splattered by traffic coming the other way.

I knew the road well, feeling mildly amused that I was going to zap the whole bunch as soon as the next curve finished, and in the process put some fat arsed capitalist who insisted on driving his Roller about an inch away from my back mudguard, firmly in his proper place.

Loitering in second at 30mph produced an annoying buzz from the counterbalanced 360° engine (almost as bad as a Triumph Daytona) and the chassis felt a little ponderous. Both problems cleared up as I screwed the engine to the red line and played footsie with the sloppy gearbox - it had taken a week's riding to become used to the feel of the box and its ability to find false neutrals if you didn't pay attention.


Third, fourth a quick blast on the useful air-horn to make a wandering MG driver get back in line and fifth, just as I cleared the last car. Jam on the twin front discs, not much feel but they dump the forks down on the stops, knocking off the speed for the next series of bends.

The Superdream has good ground clearance, but shot rear shocks and wobbly forks - it squirms over the bumps but stays on line, thanks to reasonable frame geometry and good weight distribution. The excellent riding position, with flattish bars and nicely placed footrests, helps make the rider feel part of the Honda and help make it easy to control. There was only a quick couple of curves and then back onto the straight.

I was relaxed at an indicated 90mph, the Honda was buzzing away, not exactly merrily or vibration free, when the Roller tries to get past. I'd assumed I'd left it for dead at the back of the queue, but the driver must have followed after me, a manoeuvre of almost suicidal proportions for a car of such girth. Drop down to fourth, rev counter in the red, back up to fifth, same procedure, and up into sixth, the speedo flicks between 110 and 115mph, the vibes are like a Bonnie at 80mph (double vision stuff) and the six valves and rockers sound like they are going to fly apart in a big way.


The nose of the Rolls Royce edges backwards but doesn't disappear. The next curve looms up ahead. I leave the braking to the last moment, down through the box and all brakes hard on. I'm still braking as I lurch the Honda over and it feels like it's going to flop over and die, but I hold on, not least because the Roller's still on my tail.

The 43 horses the Honda knocks out (at 9500rpm) weren't enough to lose the fat cat driver. The true top speed of the CB is between 105 and 110mph depending on age and condition. The bike I'm riding is a 1980 job with a mere 22300 miles on the clock, and it could probably hit a true 110mph with a following wind. But the Roller can probably do 130mph in relative calm and comfort. What it shouldn't have been able to do was go around corners fast (at least this is what the car mags claimed), but it stuck right on the tail of the Honda and actually had the audacity to overtake us as soon as we reached the next straight.


Revenge was mine when the Roller was slowed by yet another traffic queue, but the price of that vengeance was taking my life in my hands by shooting around the cars while in the middle of a blind right-hand bend. Unfortunately, the Roller wasn't going to let me get away that easily, it hung onto my tail all the way around. Tut, tut.

We sped along the empty straight; I was full of visions of an overheated CB400N engine poking its con-rods out of the crankcases, the vibes and noise would have made a Vincent owner proud. Apart from a very mild weave, the Honda felt stable and secure at ton plus speeds, despite the worn out suspension (new, it was very, very good).


Another bend and then another line of cars. I was still ahead, just, I shoved the Honda over the wrong side of the road, still accelerating, past four cars and I see the double decker bus coming up the road. Another three cars, ease the Honda in beside a Mini, which obligingly moves over into the gutter. The Roller purrs past and I try to look innocent. Three cars on the Rolls tries to cut in front of a beat-up Cortina, but the driver doesn't want to know.


Everyone has lost about 20mph, the Roller braked hard, looking like a whale stranded on land. In the Honda mirrors I see the red brake lights of the bus. There's no great crash; by the time the car and bus come to a halt, face to face, the traffic's cleared and the Roller can turn back into the right side of the road. By then I'm clear of the cars, happy that I finally proved the inadvisability of spending more on a tin box that many people spend on buying a house.

It was from then that I began to like the Honda. Strictly speaking, I should have dismissed the Honda as having an appalling engine design that was as much a retrograde step as the earlier CB350 was in terms of the sixties CB77. Both the CB350 and CB77 were straightforward vertical twins with two valves. per cylinder, SOHC and 180° crank (with no silly chain driven balance shafts). The CB77 looked and felt much more sportier than the staid CB350; the latter machine really having no improvements in any areas, although it was quite reliable and easy to ride and maintain.


The Superdream was a development of the dumpy CB400T Dream, development taking the fairly typical route of a new line in style (and for 1979 very pretty) and a claimed increase in power which actually resulted in a slightly slower bike despite an extra gear.

The top end uses two inlet valves and one exhaust, controlled by one camshaft and set of rockers with screw and locknut adjustment (quite easy to set up and can be neglected for long periods), a design which gives good cylinder filling but also escapes the overheating problems associated with many four valve, air cooled engines. A hyvoid chain drives the cam from the centre of the four bearing crankshaft, tensioner and chain have a life of between 20 and 25000 miles.


Two balance shafts are driven by another chain with its own tensioner that needs to be adjusted every 2500 miles and this whole drive train can be out of action by as little as 15000 miles if consistently neglected. Of course, it's impossible to balance out two pistons moving up and down together using balance shafts, because at some point in the cycle the balance shafts, themselves, will be out of balance. Thus, the Honda lacks the ultimate smoothness of a Suzi GS400, but makes up for it in letting the rider know what the engine is doing instead of the Suzuki's remoteness.

Primary drive is by gear to a wet multi-plate clutch that can start to slip with about 30000 miles on the clock. The gearbox doesn't fly apart when abused, just loses precision with age, not helped any by a gear change linkage that's decidedly sloppy after the first ten thousand miles, despite rubber gaiters on the joints.

Electronic ignition can fail after 12000 miles or may give no trouble whatsoever (this is very useful as it goes without warning). Bad starting can often be traced to poor ignition coils. The rectifier and regulator are both quite tough, although it's not uncommon for alternators to burn out somewhere between 25 and 30000 miles.

Despite the presence of power sapping balance shafts, out on the road the Honda is as fast as any of the other 400 twins, but as it's no smoother than the Yam XS400, which lacks balance shafts and has the pistons moving out of phase, this isn't exactly an achievement of which Honda should be particularly proud.


Compare the lines of the Honda engine with their earlier efforts to realise just what a low quality looking unit it really is. If Honda had placed their new cylinder head on the CB350 bottom end, then they would have had the best of both worlds. Unfortunately, many of the Japs smaller designs have to appeal to their home market first, and the rest of the world takes second place. As the Japs appear to need ever increasing numbers of technical gimmicks to keep them buying the next new model that comes out, the rest of the world have to suffer silly additions that far from making engines better, often lead to an early self destruct act - such is the case with Honda's chain driven balance shafts.


Apart from increased vibes as the balance shaft's chain and bearings wear out, the fuel economy of the CB400 is nothing to shout about. Compared with the mid-sixties CB450 twin, that develops similar power and has the same top speed, it's pretty awful. The only time the Superdream manages the older bike's overall average of 70mpg is when it's ridden very slowly. Go beyond 50mph and it quickly drops to 60mpg and cruising above 70mph gives just 55mpg. Really thrash the engine at max revs and it'll go diving down to as little as 4Ompg. It usually averages between 50 and 55mpg. This is all a great pity, as the bike has quite an efficient cylinder head design that short stroke dimensions (70.5x51mm) to produce an engine that makes useful power at the low end of the rev range and can sing along quite rapidly beyond 7000rpm.


For sure, there's none of the real urgency to be found on larger twins and into a strong wind or against a steep hill the engine develops insufficient torque to let it cruise any faster than 80mph (strung out in fourth gear). Indeed, 80mph is really the optimum speed for the Honda, the vibes are a gentle thrumming that doesn't shake bits off the engine and the chassis still has a nice secure feel.


Handling in the wet is fine, with neutral steering and enough feedback producing sufficient warning of sliding tyres. The discs are a bit dangerous as they can lock up the wheel without warning, but the rear drum is useful. The calipers need stripping down after 12500 miles. The silencers and collector box are full of holes in three years, but the engine is tolerant of non-standard exhausts. Engine casings can be a horrible mess of corroded alloy after just two years.


Paintwork and chrome are reasonable. Some of the all alloy Comstar wheels have been repaired after an accident and are subsequently a little dodgy, so check for dents and cracks. Everyone knows what the FVQ shocks stand for... unless the oil is changed every 2000 miles the camshaft bearings get written off (surprise, surprise).


When new the Superdream was one of the best 400 twins on the market. With twenty grand on the clock, the poor engine design begins its self destruct act and the sloppy suspension takes a lot of the precision out of the chassis (but it's still pretty stable). The reliability of the GS425/450 rather puts the Honda in the shade in the used market.


Bill Fowler