Honda CB900

Trying to take a Kawasaki GPz900 with a six year old Honda CB900 wasn't, perhaps, the sanest way of spending an evening. I figured that I was in with a chance because the GPz jockey was wearing new black leathers and didn't look at all happy perched on the Kawa. The road was a wide two lane carriageway with enough room to pass a car without crossing the white line. There were long straights where the Honda was screamed at the redline in fifth to keep up with the more powerful and aerodynamically efficient GPz. If there hadn't been any traffic or violent bends then the Kawa would have disappeared off into the sunset. The GPz was reluctant to ride around cars on the bends and didn't have the nerve to blast away at cars that had the audacity to drive too near to the centre of the road.

The Kawasaki was three cars ahead. The road was just starting to curve to the left. The pace was slow, sixty or so. Flicking down the box to second gear, a handful of throttle and the clutch let out with a bang , the bike wrenched towards the centre of the road, squirming as the front wheel followed the raised surface of the white line. The back wheel jumps off line as power is momentarily lost as third gear is engaged. The speedo flicks past the ton as the CB comes parallel with the final car. It has to get past because it needs to cut across the road as the curve tightens up. Backing off the power at this point would send the Honda veering off into oncoming traffic. Fourth gear, the bike a foot over the wrong side of the road, the car driver decides he wants to race. But I'm having none of that, I'm far enough past the car to wrench the Honda upright and make a straight line out the final arc of the bend. I get blasted by the driver's horn, but my straight line takes me inside the GPz leaving me a little ahead as we exit the curve.

I struggle to turn the Honda out of the gutter, directing it across the front of the Kawa, revving the engine into the red in fourth. If the images in the mirrors were not so blurred I'm sure the GPz pilot must have looked surprised at this manoeuvre. But the movement is a little too sharp. To line the Honda up with the direction of the road requires another vicious wrench on the handlebars. This happens as the front wheel hits the centre line again. The Honda reacts by flipping the handlebars out of my control. They go from lock to lock, but settle down almost as quickly as they started giving trouble. This time. The Honda is on the wrong side of the road, level with a car full of kids who seem to be laughing at the antics of the bike. Fifth gear with a clutchless change; the throttle wound all the way around. The transmission objects to this, a small tremor shakes the bike. The 130mph wind tries to wrench my crash helmet off, despite my being crouched down by the instruments. The Honda needs much more than flat bars and reasonably placed footrests.

A long straight, the Honda flat out at an indicated 140mph. The road suddenly deserted - except for a Kawasaki GPz 900 somewhere on my tail. There's no way I can twist my head to find out how close he's getting. The alloy swinging arm and Koni rear shocks are helping to keep the Honda reasonably stable. The extra weight on the front wheel from the flat bars, help to stop the forks from misbehaving. As the road unwinds, there's more time to ponder just how bad secondary vibes from four cylinder engines can become with the rev counter courting the redline. The handlebars are the worst affected, although gripping the tank tightly with my knees kind of make massage parlours redundant. I sensed rather than saw the GPz on my tail. There was nothing extra I could do to make the Honda go faster. I was already skirting dangerously close to the mechanical limits of a DOHC engine that did remarkably well to extract 95hp from a design firmly rooted in seventies two valve/cylinder technology. It was a long walk home if the Honda decided to break a camchain, seize its pistons or tangle its valves; events that were not particularly rare on this machine.

The GPz went past, the rider seated relatively comfortably behind his fairing. I gained a little speed by slipstreaming him, keeping on his tail until we both started to brake sharply for a series of bends. The Honda doesn't like slowing down very much. Equipped with twin discs out front and a single rear disc, there's plenty of stopping power, but if it isn't used carefully the bike can start to jump all over the road in protest. Tied up in knots is an understatement. I was rushing down the box to find second to have an acceleration advantage, when I realised I was going to enter the curve about 20mph too fast. I had time to notice the way the Kawasaki just glided around as if on rails. Braking while putting out too many revs as second finally engaged sufficiently confused the chassis to have the front end trying to go straight on, while the back wheel tried to move outwards. I let the Honda drift over to the wrong side of the road, getting upright and applying some power.
 
This got me around the first curve, the only problems was that there were several more in the way. The Honda weighs 530lbs, all the controls are heavy enough to delight Harley owners and there's enough slop in the transmission to impress Hesketh engineers. This makes any kind of fast bend swinging very tiring. The only way to ride the Honda through tight curves is to keep the bike as upright as possible. Point and squirt, across two lanes of carriageway when possible and hang off the bike like some speeded up racer. I was congratulating myself on some kind of proficiency in this department - at least, I could still actually see the GPz - when the fuel ran out. Now, when the CB900 runs out of fuel it doesn't give any kind of warning, no gentle splutter from the engine. The engine goes dead. The sudden loss of power while the Honda is committed to a particular line in a bend, results in a wildly gyrating back wheel, and a directional change in favour of cutting across the road for a game of chicken with bored car drivers. 

Flicking the bike upright restored the fuel supply for long enough to navigate the final bend and flick on reserve. A glance at the mileage revealed that the Honda had averaged 28mpg. The best I'd ever achieved was 40mpg on a 70mph motorway drone. The usual cut and thrust riding averaged 35mpg, but this was staying well clear of the redline, in deference to the mechanical frailty of the engine, which had 35000 miles on the clock. The engine also needed a pint of oil every 300 miles, so it's an expensive beast to run. Throw in a new rear tyre at 4000 miles and a new front at 5000 miles, together with a new chain at that mileage, and the DHSS needs to increase the dole by rather more than the claimed rate of inflation to keep young hoodlums in the fast lane. But I can't quite see the government understanding this line of reasoning. I easily caught up with the GPz once out of the curves, because there was a police car sitting on the side of the road. I resisted the urge to wave as the Honda droned past on the minimum of throttle in fifth gear to disguise the heady noise the exhaust makes when on cam. At a gentle sixty there was no vibration, and I could actually study the police car in the mirror. It didn't appear very interested in us. At these low speeds the Honda felt very stable and secure with none of the impreciseness found at speeds in excess of the legal limits, and none of the feeling of living on a dangerous knife-edge. The duplex tubular frame had the usual excessive mass and power to contend with; the front forks were never too hot when new, now they were definitely worn and not even the old remedy of stiffer springs did much to help them gain a new lease of life. The addition of an alloy swinging arm helped tighten up the rear end, but the swinging arm mounts are not particularly well designed, so there's still enough flex to make life, er, exciting.

The sight of the police car sobered up some of our high spirits, we were content to run along at more reasonable speeds. This was useful, to say the least, because the road surface had turned bumpy as we began to approach the out skirts of a town. Even the Kawa's back wheel was stepping out of line. The Honda felt as if it was going to flip over and lay down dead. I cursed complacent Jap designers who never had the opportunity to ride this kind of machine on such dilapidated roads. Fortunately, the road was straight, for bumpy curves and 530lbs of malevolent metal don't mix too well. When new, the Honda displays just as bad terminal tendencies. The tautness of the suspension and lack of wear in the bearings is wrecked by lack of damping in the rear shocks and a weak swinging arm. Failure to replace these items as soon as possible results in a bike that exhibits the same suicidal urges as a 1950 Triumph 650 and one that is capable of delivering these vivid kinds of speed wobbles at much higher speeds than that unhappy collection of ironware that has the audacity to claim classic status. If secondhand bikes don' t have these modifications check out the chassis for signs of crash- damage.

Entering town found me trying to keep up with the Kawa as its owner manoeuvred around the cars with the ease of a trail bike owner. Or this is how it seemed, as I tried to obtain some leverage on the handlebars to overcome the Honda's low speed insistence in carrying on in a straight line. Once the Honda starts to change direction, it then tries to flop over, which just about manages to produce the worst of both worlds - poor high speed stability and poor flickability. These problems come to a head in the wet, when things can easily turn very nasty. The way the motor can suddenly turn on the power, so much fun in the dry, can catch the back wheel out, sending it lurching off. The weight distribution, steering geometry and integrity of the frame do little to help bring the wheel back in line. Backing off the throttle solves that problem, but in bends doing that upsets the front end.

What can be corrected by muscle in the dry, results in a series of slides in the wet. At least the brakes are sensitive and don't suffer wet lag. The only solution is to ride very sedately in top gear, while 125 owners shoot past. Engine life varies enormously, depending on the level of abuse and the efficiency of maintenance. The real tough guys can wreck the top end and wear out the transmission by as little as twenty thousand miles. This requires neglect of oil changes, valve clearances and carb balance. A new camchain and tensioner are usually needed by 30000 miles, although this particular bike was still running on the original components. By forty grand it may need new camshafts and a rebore.

Some bikes, that have been ridden sensibly and maintained regularly, are still running with as much as sixty grand on the clock. Bikes with this kind of mileage and with an unknown history are not recommended. Good engines don't make very much noise and shouldn't have any oil leaks. Anything with more than twenty grand on the clock and more than a couple of owners has to be avoided unless it's really cheap. 

I followed the Kawasaki into a petrol station. I couldn't hear the GPz engine because of the noisy Honda exhaust and because the valves sounded as if they were knocking holes out of the pistons. Oil was running out of the cylinder head joint and dripping from some worn gasket under the engine. The rev counter was fluctuating wildly as the engine failed to rumble along at a constant tick over.

As I tried to unlock the petrol cap, I noted my fingers were shaking. I put this down to the secondary vibes, although the quaint handling foibles might have had something to do with it. For some reason, my suggestion to the GPz rider that we should swap bikes wasn't accepted . He didn't seem to believe that I was editor of this magazine, either. Sometimes I find it hard to believe myself.

I decided to let the GPz go its own way. I'd more or less proved that a little bit of craziness could compensate for the Honda's age and inherent failings. Of course, there's nothing to stop GPz owners going crazy, except perhaps the thought of over three grand being on the line. That's enough to kill the spirit of many motorcyclists, leave them cold to the delights of high speed fun and games. I gave the Honda ten minutes rest, to let the engine cool down and close up the clearances. It sounded much happier when I caressed the starter button. As four cylinder four strokes go, the Honda can't compete directly with any number of rival bikes from Jap and Euro manufacturers. I could write another 3 pages on the handling deficiencies. But the main point is the bike's cheap (from £300 up) and it's, er, fun. It was no surprise that when I glanced in the mirror there was a manic kind of grin on my face...

Bill Fowler

Triumph T140V

A few miles north of Stroud there are a series of interesting roads. Small but steep hills are spread over a couple of miles. Reaching the crest of one hill gives a view far enough ahead to safely make the apex of the next rise. The roads are narrow country lanes, just wide enough for two cars to scrape past in certain spots. The Triumph would leap over the crest, the revs momentarily flicking into the red as the back wheel lost contact with the road. Then it was a full throttle thrash down the slope, the game to make the ton before the bottom. The stomach lurches as the Triumph starts up the vertical, like an out of control Big Dipper. The momentum and torque carry the bike forward up the steep incline, until the top is attained and the whole cycle starts again. At certain points in the route, the road swings violently to the left or right. Before the Triumph has a chance to recover from the effects of rapid gradient fluctuation, it's heeled over, scraping sidestand and footrest, braking deep into the corner. Bumps, gravel and cow shit try to push the narrow patches of rubber off line. The Triumph takes it all in its stride. The combination of light mass, stiff frame and taut suspension are difficult to catch out.

And that, folks, is just about all the Bonneville is good for. On tricky country lanes when feedback from the road and agility are the main concerns, the Bonnie's other failings are momentarily forgotten as the good times roll. As the speedo flicks past an indicated hundred miles an hour at the bottom of one of those hills, the vibes have bypassed the rubber mountings of tank, footrests and handlebars. Everything gets the shakes. Good training for pneumatic drill operators, but a kind of hell for long distance speed freaks. Between sixty and seventy five, the engine is relatively smooth, with top gear touring just about plausible. Any extended excursion into higher speeds is met with nasty vibration and short engine life. The ancient engine design is sabotaged by restrictive noise laws and emission controls. It's power output is little better than Jap 400/450 twins. The later bikes are rather more usable due to lack of vibes and inherently strong engine designs. They also have better fuel economy. This all tends to leave the poor old Bonnie out in the cold.

Back in 1937, Triumph produced the first commercially successful vertical twin. A design severely restricted by manufacturing techniques, that has been updated over the past fifty years with hardly any innovation or creativity. The result, a 750cc engine that cannot stand up to the levels of neglect and abuse normally inflicted on modern motorcycles. And an engine incapable of safely delivering enough power to satisfy the market

The 744cc long stroke (76x82 mm) engine has a 360 degree crank supported by two small bearings. Crankcases are vertically split, the main machining restriction on the possible number of bearings. Triumph used to have enough trouble making two holes line up, let alone three or four. Thus the crankshaft is unsupported over most of its length. Stressed by both combustion forces and the unbalanced primary vibes, it's in for a tough time.

A set of gears drives two camshafts mounted either side of the crankshaft. The camshaft operate tappets, which control pushrods acting on the valves through rockers with screw and locknut adjustment. The effects of vibration on crankshaft and valvegear are rather horrific. If ever a design needed a four bearing crankshaft then the big vertical twin is a suitable case for treatment. Engineering horrors are continued with chain primary drive that has a self destruct tensioner. Again, the same old story of a lack of machining integrity stopping the use of a vastly superior gear primary drive.

The engine becomes dangerously unreliable if tuned beyond the stock 50hp, a figure little better than sixties Bonnies. In those old days few bikes could see off the Triumph 650. Only the brave and tough aspired to ownership, which shows just how times have changed. The 750 needs regular attention every 500 miles.
Adjust valve clearances, contact breakers, carbs and primary drive tensioner. Tighten up all the engine and chassis bolts. Mildly run bikes go until around 20000 miles before needing a rebore, reground valves, new primary chain and new clutch plates. Hard used bikes can need attention by as little as 10000 miles.

If the Triumph engine shows little improvement over the 650, twenty years older, then at least the rolling chassis shows some kind of definite progress. Until the early seventies, Triumph frames had quite a nasty reputation for high speed wobbles. True, each year often saw a mild improvement, the most noticeable occurring when additional swinging arm support was provided by plates between engine and frame. But the Triumph never came near to the precise and stable nature of its Norton rival. Under the influence of the BSA management, Triumph introduced an oil in the frame unit that offered a huge leap in handling ability. Initial models had a seat height suitable only for giants, but by the time the 750 was introduced it was down to a more reasonable level. The large diameter main tube flows around the engine, from steering head to swinging arm mount. Two smaller tubes go from steering head to cradle the engine and provide extra support for the swinging arm, eventually ending up supporting the seat rails.

Suspension is stiff, limited in movement and gives plenty of feedback from the road. The end result gives the Triumph handling ability almost up to Norton Featherbed standards. The Bonnie needs a little more muscle to change direction, but it feels just as stable and precise. The security afforded in wet weather, when the chassis never holds any nasty surprise and the rider is always aware of the tyres' reaction to the road, is ahead of any other modern bikes, except perhaps certain Wop exotica. The Triumph is aided by having only 400lbs to shift, and by the narrow engine allowing a low centre of gravity. These allow steering geometry that gives high speed stability without having to worry over flickability in traffic. The suspension may be too hard, but fitting some of the ultra trick items now employed on modern fours would probably wreck the whole feel of the Triumph.

The disc brakes at each end work quite well in the dry. The front loses feel in the wet, while the rear tries to lock the wheel. Lever pressure on the front brake is excessive, but there's enough feedback to avoid locking the wheel. Better than early seventies Jap bikes, they are hardly up to modern standards. Indeed, a decent set of drum brakes would give just as good stopping power, while fitting in with the character of the bike. Front disc pads go for 6000 miles, while the rear last for 10000 miles.

The multi-plate plate clutch has inherited clutch drag from the original 1937 machine. It's necessary to free the plates by kicking the machine over before it is started. Failure results in a bike that lurches forward and stalls when first gear is engaged. Clutch lever pressure is far too high and very tiring in town. Clutchless changes are possible, but lead to early failure of the five speed gearbox. Gear selection is precise, but can't be taken too quickly. Problems may occur with changes between first to second and third to fourth, as well as selection of neutral. The gearbox is one of those complex devices that sprays tiny bits all over the garage floor when stripped down. Chain final drive needs adjusting every 750 miles, lasting for 7500 miles. Running on a worn chain is dangerous because it likes to snap, locking up the transmission and breaking into the engine compartment. Nasty.

Starting the Triumph is no problem if you're used to British twins. Neither the cams nor compression ratio are radical enough to cause the motor to kick back. Some later versions of the 750 had an electric start, but this never managed to work from cold. It was useful for starting a stalled engine. Third or fourth kick is the normal point at which the engine rumbles into life. Fitting electronic ignition reduces this to first or second kick.

Fuel consumption varies around the 50mpg average. The best I ever achieved was 60mpg, when gently pottering down some A roads . Trying to cruise above 80mph returns as little as 35mpg. The single carb Tiger is hardly any slower but improves economy by as much as 10 mpg. Electronic ignition helps the Bonnie to average 55mpg. Neglect of the regular 500 mile servicing increases consumption to an average of 40mpg. Continual neglect of maintenance will send the ignition timing far enough out to burn holes in the pistons. And exhaust valve clearances will tighten up until clouds of smoke start coming out of the exhaust due to burnt exhaust valves. Out of balance carbs increase vibration throughout the rev range. It can get so bad that mudguards, exhausts, petrol tanks and headlamp brackets all start to fracture.

Lights are standard Lucas units, which blow frequently and don't provide sufficient illumination for fast riding on unlit roads. Budget for new front and rear bulbs every 1200 miles. Indicators are a sick joke. They either fall off due to excessive vibration or flash in a random enough manner to give epileptics severe convulsions. The Lucas rectifier and zener diode have a 5000 mile life before they are affected by vibration or the erratic nature of the electrical supply. The alternator suffers from overheating, vibration and poor mechanical support. Life varies between five and fifteen thousand miles. The switchgear lacks a positive feel and can short out when subjected to wet weather. The wiring loom is a terrible mess. It is usually too short and wears away at the steering head when the front wheel is turned. The stoplight switch for the rear brake is situated to pick up the maximum amount of road debris. It lasts for around 5000 miles. The speedo reads 110mph, and all the idiot lights blow with too predictable regularity. The rev counter gyrates wildly whenever the motor enters one of its periods of bad vibration. Both instruments need replacing after as little as ten thousand miles. Most owners will have uprated the electrical components and rewired the bike.

The overall appearance of the Bonnie is of an awful mess. There are so many small components that look out of place, that even the beautiful lines of the engine can't salvage the character of the bike. But the potential is there. Of all the British bike builders, Triumph have always built the most suggestive looking engines. The lines of the frame do not interfere with the styling possibilities, and - properly done - enhance the image of the bike. It takes very little to clean up the Triumph's act. For street credibility it cones second only to those stripped down Harleys. It just needs a little attention to detail.

The Triumph's main Jap rival is the Yamaha XS650. The Yam is a hundred pounds overweight and fitted into a dangerously flimsy frame. Where the Yam is limited to 70mph cruising by its road manners, the Triumph is limited to the same speed by its production of excessive vibration. The Yamaha also has pistons that move in unison, but there the similarities end. The XS has horizontally-split crankcases and a massive four bearing crankshaft, with central chain drive to a single overhead camshaft. The Yam engine is just as simple to maintain, but needs this maintenance at infrequent intervals. Vibration and oil leaks are drastically reduced. Performance and economy of the XS is slightly better than the Triumph. Dare I suggest that this is the kind of engine that Triumph should have produced. And that Meriden missed a great opportunity by not fitting XS650 engines into their rolling chassis. Sure, it wouldn't have been truly British. But it would have been jolly good fun.

It's somewhat ironic that the first of the British twins is now the only British bike on sale. As a practical motorcycle the Bonnie has nothing to offer. Under limited circumstances it can be fun. If all the effort is worthwhile depends on if you can view the Triumph as a poor man's Harley. Triumph 750s can be picked up for around £500. Strip the thing down. Throw away all the junk (indicators, filters, silencers, disc brakes, cast wheels, etc). Fit one of the small tanks, drum brakes and loud exhausts. Use a single carb and mild cams. Then, and only then, you might just have a practical and interesting British classic.

Johnny Malone