I don't blame anyone other than myself for buying this bike. Youthful enthusiasm overcame all other realities, even the most abominable cost of insurance. So there I was, 18 with a 1982 machine that looked like it had gone around the clock, although the speedo only said 24,637 miles. A new MOT had been part of the deal, but it had probably been done by a back street merchant who wasn't too particular.
That was three years ago and the Honda is still running, having done another 42000 miles without having to strip down the engine, which I thought rather good going - better than I expected, anyway. Predictably, it wasn't all plain sailing, along the way I had to make various mods to the chassis and do some refurbishment work.
Riding impressions first, though. It has to be admitted that the Honda is a hefty lump. Even with a lightweight 4-1 exhaust and some prudent chucking of unimportant components, it still breaks the scales at over 500lbs. As I weigh less than eleven stone myself, this is a massive lump for me to chuck around.
Low speeds are bad enough to be back wrenching. I still have not become entirely used to the way the thing will try to rapidly flop over. Between 30 and 80mph the Honda is at its best - the CB came with Koni shocks and a fork brace which help damp out the tendency of the frame to let the machine weave in this speed range. It never has felt like it is on rails but doesn't become frightening unless more than 80mph is attempted. Then it's a case of all the mass ganging up to send the machine into all kinds of interesting traumas.
Decent tyres help a lot here, the Honda is one of those bikes that does not like to run on worn rubber. Arrowmaxes or Metz's offer the best combination of grip and wear. Thus equipped, I have cruised at 90 to 100mph for long distances without experiencing wild speed wobbles but the bumpier the road gets the larger the weaves become.
The most I've put on the clock has been 135mph. I only did this the once, as hitting a slight bump sent the handlebars into wild oscillations. Using any speed above the ton is asking for trouble. This has had a useful side effect of preserving my licence and not ruining my engine.
Not that the amount of secondary vibes above 7500rpm encourages wild thrashing of the DOHC engine. A particularly annoying patch of vibration also hits the bars and pegs at 70 to 80mph in top, which can be most annoying on gentle motorway blasts. As the engine has aged, so have the vibes increased - to the extent that I now have to go over the machine tightening up loose bolts after a long, hard thrash.
Power delivery is surprisingly mild below 5000rpm and although 75 horses are claimed an awful lot of them are absorbed in overcoming the momentum of all the mass. Still, ringing the neck of the engine in the lower gears can be grin inducing but the motor is a bit of a curious design in having neither much torque nor a really spectacular power punch.
All the stranger, then, that the engine needed frequent maintenance sessions to keep it in tune. With sixteen valves and four carbs to check, many a Sunday morning was wasted. I got into the habit of checking them and changing the oil every 600 miles. Judging by the stories other owners have related of top end demise at low mileages the effort was more than worthwhile.
Even now, once set up properly, the engine is surprisingly quiet, with only the reassuring (they all have it) clutch rattle, a leftover from the original sixties CB750 four, a bike I once had the pleasure of burning off in no uncertain terms. I am not impressed by those overpriced classics.
I suspect they may well have managed better on the fuel front, the FB rarely did better than 40mpg, usually turning in 35mpg. In the early days when I was getting used to the bike and the motor was that much newer, a best of 55mpg was achieved, but I doubt if it will ever repeat that. Oil consumption is also high, about a pint every 200 miles, which is a bit naff given how often it's changed.
Other consumables are reasonable given its mass - 7500 miles for a new set of pads all round, tyres in 6 to 8000 miles and a fairly cheap chain every 10,000 miles. The latter could do more but only at the expense of mucking up the gearchange, which was never what could be called smooth and precise even when the bike first came into my hands, or, indeed, when it first shipped out of the showroom. Anyone who has ever owned an old Honda will know the experience only too well.
It hasn't needed any internal attention, though, which is more than can be said for the chassis. Bits that have been replaced include the fuel tank (rusted through), seat (fell apart), calipers (several times as they corrode up) and all the electrics. A malfunctioning rectifier sent pure AC voltages through the wiring which tried to turn the bike into a blaze big enough to ruin my leather jacket, which was used to smother the flames.
This gave me the excuse I'd been looking for to do a respray of the frame, which by then was more rust than black paint. The bike was easy to pull apart, although three were needed to lift the motor in and out. I also welded in some extra steel sheet around the headstock and swinging arm mounts, the latter had always had a very slight hinged-in-the-middle feel.
I was surprised at how much I missed riding the CB over the two weeks it was off the road. By the time it was ready I was nearly jumping with joy. Strange how these bikes can get to you. I was disappointed to find that all my efforts with the welding torch made absolutely no difference to how the Honda handled!
Perhaps what I like most about the CB, despite its handling peculiarities (which can mostly be adapted to), is that it's one of those bikes that will do anything and go anywhere, short of something silly like trail riding. As my only machine it has to be hustled back and forth every day to work - even in the depths of winter the motor purrs into life (sensitive to choke position, though). Riding on ice covered roads proved especially traumatic, as the Honda is not one of those bikes endowed with a great amount of feedback from the tyres. The first you know about a tyre sliding away is the machine scraping along the tarmac.
I had quite a few accidents in winter until my riding became very cautious and my reflexes quickened up. No serious damage to either bike or myself, but I did fall clear of the Honda, having that massive brute land on top of myself would probably be terminal. I never came off at serious speed, helped by the disc brakes, which when they were not corroded up, performed heroically, producing such short stopping distances that many a blind cager was able to give thanks to their efficiency - after he had got over the amount of verbal abuse I showered upon his shaking form.
The bike is slightly too wide to sneak through the narrower gaps in heavy traffic, so I've taken to giving the cagers a blast on the air-horns, which usually has them swerving out of our path. Some lout occasionally goes into a rant about such treatment, poking his head out of the cage window to scream abuse at me, but by then he's usually eating my exhaust fumes, so no great problem.
I did try some high and wide bars, to aid chuckability in town, but found that they tended to scrape off car mirrors. The first time it happened, a loud detonation made me think that something had snapped off the Honda, it was only the car driver furiously trying to catch up with us that made me wise to what had happened. I dropped a couple of gears, nearly had the front wheel off the ground (wheelies are not really possible) and was out of there in a hurry in a frenzy of vibes and acceleration. One up to the biking fraternity, but I did change my route to work just to make sure he wasn't loitering with intent.
That happened quite recently, which shows there is still a bit of go in the old girl. Hard to say how much longer the motor will last, the vibes and oil consumption would suggest not very long but the quietness of the motor offers some hope that she might make it around the clock.
It will soon have an easier life as my second bike, I've bought a dead CBX750 and a good motor from a breaker. Once this bolide is on the road the older Honda will be a weekend plaything, a nostalgic trip to my misspent teenage years (god, I sound old at 21!). I shall be interested to experience the contrasts between these two Hondas.
Brian
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I acquired my CB750KZ from the breakers. It looked like quite a simple job to repair and I hoped to ride it for a year or so and then sell it at a mild profit. The most obvious faults were twisted forks, bent front Comstar, wrecked clocks and dented petrol tank. The breaker was (was being the operative word) a mate so my inspection of the machine was less thorough than it should have been.
Back in my luxury garage, er, living room, the full extent of my foolish behaviour was revealed. The front end came off easily enough, then the tank. Revealed were bent frame tubes around the headstock and indented exhaust tubes. Before I tore the engine out I tried to get it to turn over by rotating the back wheel. It was stuck in gear and no amount of force would make the back wheel turn. To cut a long horror story short, the reason the bike had crashed was because the engine had seized.
The frame, forks and wheel were dumped into a nearby specialist who in exchange for a £120 straightened everything out. Meanwhile, I was working on the engine. The cylinder head had two studs seized which snapped off rather than come undone. Just as well I had a helicoil kit! The head came off, the valvegear looking in good shape. The pistons were all there and apart from a bit of carbon build up looked as good as new. The cylinder was tyre-levered off and there were no signs of seizure.
Strange, but the crank would still not rotate. I had just dismantled a perfect top end for no good reason! I turned the engine over and split the crankcases. This time three bolts snapped off! Oh my god, look at the gearbox. One cog was stripped bare of teeth, which had stuck between the teeth of the other gears. I hate gearboxes and now I had to take this one apart. The cause of the break up was a shot gearbox sprocket bearing that had allowed the shafts to rotate out of line. The result of a too tight chain?
You don't see very many KZs on the road, they never sold in vast quantities. You see even less in the breakers and finding one, despite phoning around all the breakers in MCN, proved impossible. When I enquired of my local Honda dealer of the cost of a new set of cogs, shafts and bearings he rubbed his hands together, gave me a wide grin and doubtless thought about booking a winter Holiday in the Algrave on the back of the profit he was going to make.
I looked at the box again and it seemed to me that I could get away with just one new cog and bearing. The bearing I got from a bearing factor at a third of Honda's quote and paid up for just a new cog, much to the dealer's disgust. A pattern gasket set was purchased by mail order and I was ready to waste another weekend reassembling the motor.
When the box was back together there seemed a bit of a backlash between the gears and I told myself to take it easy on the changes. It all went together easily enough, my only real problem getting those four sets of piston rings back into the cylinder. Talk about needing four pairs of hands.
Reassembly of the motor coincided with delivery of my straightened chassis components. I decided to leave touching up the cosmetics and removing the dents from the petrol tank until I was sure that the motor would run. It proved possible to repair the instruments with Superglue and I replaced the cracked glass by cutting up an old visor to suit.
Much heaving and humping, swearing and cursing, saw the lump back together. I had to buy a new wheel spacer as that had disappeared. Much whirring of the motor ensued until it eventually coughed into life and settled down to a lumpish tickover. Out through the back door, down the garden and out into the lane. It felt bloody awful. The motor spitting back out of the exhaust, the bars shaking in my hands and the front brake refusing to work, the lever came all the way back to the bars.
Back home, I bled the brake lines, reassembled the exhaust system with some goo on the joints and inflated the front tyre from 15 to 30psi. Right, you bugger, now start behaving. And it sort of did, up to 50mph anyway. The engine ran cleanly, it steered as well as my Jawa 350 and now braked with enough force to fling the rider over the bars. However, there was a disturbing whine from the gearbox and it crunched rather than snicked into gear.
Second and third were particularly noisy and the transmission felt very jerky at lower revs. Beyond 50mph the engine misfired and I had to slip the clutch and rev the balls off it to get through the flat spot. Could the large dents in the downpipes be upsetting carburation? There was only one way to find out. The only way to fix the downpipes was to cut out the damaged area and reweld some new tubing in place. It looked a right mess when I'd finished but carburation had, indeed, improved.
A new 4-1 was bought at the motorcycle show for £80. It was cheap because it was of the baffleless type and strictly speaking illegal to sell. This went on with only a few hammer blows and I then spent a weekend trying to set the carbs up to suit. I failed and had to hand the bike over to a dealer. £75 poorer, the exhaust turned out not to be such a bargain.
Apart from the noise, performance was transformed. It would now rev straight up to 10,000rpm without a moments hesitation and the acceleration threw one young lady right off the back. I howled around town giving aged citizens heart attacks and police officers a reason for their jobs. It sounded especially good on the overrun. More importantly, I could no longer hear the gearbox whine. Come to think of it, I probably wouldn't hear a Jumbo jet if it passed a foot above my head.
Encouraged, I finished off the cosmetics, including knocking out the worst of the tank's bumps and then filled in the remaining ones. A complete respray in candy red improved the appearance no end. Polished up it looked the business. Pity it wasn't that good to ride fast. It would get 130mph on the clock without too much of a contortion act but it weaved and wallowed, generally feeling as if it had flat tyres or a few loose bolts. I checked everything but could find nothing wrong. Either something was not straightened accurately or it does that from new.
A ride on my friend's immaculate CB750K1 convinced me that the older Honda fours were really bad handlers and I had to rush home for a new set of undies. I decided that my model wasn't so bad after all. The engine got no attention and required none over the 15000 miles I did in the year I had it. The bike had 12500 miles on the clock when I bought it and a new set of Roadrunners that were still there when I sold it.
The chains only lasted for 3000 miles - something seriously wrong with the transmission, obviously - although I did not have to change the sprockets.
Once it was rebuilt I got some good use out of the Honda but my awareness of the frailty of the gearbox meant I did not trust it on long journeys, which, given its massive weight and girth, is what it would have been most suited for. Everyone thought it was rather strange than I used the CB around town and the Jawa to go on holiday!
I managed to make about a hundred notes on the bike when I sold it, as low mileage fours of this vintage were very rare - I had about 20 phone calls! That £100 profit is after every penny, save fuel, that I spent on the bike, so I had a year's riding for nothing and a lot of fun into the bargain. I went and bought a CBR600 off another breaker but looked at that one very carefully before I parted with my money this time!
I was more relieved than sad to get shot of the Honda - it looked fine, sounded great, had arm wrenching acceleration but there was no way I could ride it fast on anything other than a motorway. Not my idea of fun.
Terry Smithson
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The first of the DOHC Honda 750 fours has never received a good press, with tales of engine blow-ups, suicidal handling and general poor longevity. But money talks, and an immaculate, 10,000 mile example for £750 was too hard to resist. I doubt if there's a cheaper way of getting hold of an 130mph machine in good nick. The owner was young but obviously intelligent, who threw in the workshop manual and the advice that I should change the oil every 1000 miles, making sure I used good quality 10/40.
Immediate impressions were of power (the previous bike was a GSX250....), secondary vibes above 5000 revs and heavy if solid handling. I'm sure that pedestrians would've glanced admiringly at the CB had not the 4-1 exhaust let loose a gruesome howl. Arriving home, the ancient crone who lived next door immediately rushed outside and started screaming at me. She'd been horrified by my leather jacket, the excess of friends who turned up at unlikely hours and the suspicion that I was debauching her grand-daughter (which I and my mates were but she wasn't complaining). The noise was the final straw, which had her hopping up and down, threatening all kinds of horrors (one of her sons was a cop.....). I gave her my nicest smile, as usual, but otherwise ignored her.
The next day I went for a long, stimulating ride. At over 500lbs in mass, and with flat, narrow bars, the Honda was a bit pig-like in the tighter corners. The exhaust would grind away on the left side, sending shudders through the chassis and increasing the rate at which my hair was going white. Despite that, the Honda wasn’t wrenched off the ground by the undercarriage wrecking the council's fine efforts at road repairing.
I really had to summon up all my nerve and energy to swing her through the tighter series of bends at a speed greater than a restricted 125 - I soon found that all kinds of youths would take up the challenge of showing up the CB's aged design and peculiar steering geometry.
On any bit of straight, the throttle could be wound on hard in most gears, with a resulting howl and butt loosening burst of acceleration. I'm sure quite a few guys thought their end was nigh when the bouncing and buckling Honda warped past them, blowing away hearing aids and setting off alarms. One good point was that above 5000 revs so much vibration afflicted the mirrors that I had no idea what kind of carnage I left behind.
The buzzing mirrors, that would even occasionally twirl loose, made it very difficult to ascertain if the white vehicles behind belonged to the plod. On that first hard ride, twice I'd slowed down to most moderate velocities to let what I thought was a jam-sandwich pass, but which turned out to be a mere civilian. Angered I roared past them not needing the horn to show my angst.
The cops don't need much excuse to pull bikers over and the exhaust had them leaping up and down several times. You have to hand it to British cops, they are almost alone in the world in not looking like they take bribes; in most countries you can smell the greed on their bodies. I was a bit surprised, then, to have one guy lean out of his window at the traffic lights, suggesting that I hand over fifty quid, but they roared off when I muttered something about having to go to the cash-point to raise that kind of dosh. Whenever I suspected that there were any cops around, I clanged into top and rode at 1500 revs.
That left the exhaust moderately rather than violently noisy, the four cylinder mill able to chug away like an old British single. At least until some acceleration was needed, whacking open the throttle resulting in the chain trying to disengage from the sprockets and the engine trying to cut out. No, a drop down through the gearbox was definitely needed, which was at its worst on downchanges, a fifty-fifty chance of ending up in a false neutral. Changing up through the box was a delight, generally, with a missed change only likely to occur between first and second when I wasn't paying full attention.
That usually happened after a couple of hours in the saddle, my arms and hands growing tired of all the effort involved in hurtling the machine about. The controls initially felt light but it's surprising how heavy the throttle and clutch can become after a few hundred miles. On motorways I longed for a cruise control, especially as the saddle, which looked either new or if it had been re-upholstered, proved supremely comfortable, aided, no doubt, by the sensible riding position.
Secondary vibes also turned the ride unruly, the bike smoother at 90mph than 70 to 80mph, which invariably meant I rode illegally whenever possible. All the cagers seemed to suffer from a similar problem so I never stuck out from the maddening crowd. Quite why the engine should buzz so heavily that engine bolts came loose and cycle parts bounced down the road, is hard to fathom as later experiences with newer fours were much smoother.
Any fear that the motor might be on the way out was unfounded because it ran and ran without any failures in 45000 miles with just the 1000 mile service and the odd filter swap. I narrowly avoided being strung up when the exhaust rotted through, even at tickover the noise caused dogs to go berserk, dustbin lids to leap up and down in accompaniment, and a run on headache tablets. Great fun was had running on the open downpipes for a while until a used Motad was found for twenty quid. This wasn't meant for a CB750K but was persuaded on with the aid of a large tyre iron and made me the most popular guy in the neighbourhood, as it let loose a mild bellow in comparison.
Other cycle parts proved good, needing no more than a weekly polish to maintain an as new state. Recently, I had a little trouble with the fuel supply clogging up, debris in the tank a sign that it was rusting from the inside out but there were no particularly weak spots in the metal, so it'll last for a few years with regular clean outs.
The bike and I have grown into each others ways, as one tends to do after a few years with the same machine. New spongier grips, subtly altered riding position and a taller final drive set of sprockets, all combined to give the Honda a much more assured feel, well able to cruise at the ton all day long. I've given up going any faster than that, though - whether because the Honda feels like it wants to throw me off or merely because I've become old and sensible, is an open question into which I don't delve too deeply.
CB750K's are still quite common on the road, I even know of one fearsome device with a CB900 motor shoehorned in, though it would make more sense to fit the later and better CBX750 mill. It's possible to buy a nice one for around a grand, though I've seen them advertised for twice that. Buying a rat for £400 to £500 is another alternative, but when the engine finally goes it does so in a big way - main bearings, primary drive and bores, as well as burnt out valves and even the occasional cracked cylinder head.
More than many an aged bike, cosmetic condition gives a strong clue to the internal strength of the motor, those that haven't received a weekly dose of tender loving care go off quickly and it's a good bet that such beasts haven't had their oil changed frequently. The handling's the worst point, the engine the best, backed up by a reasonable frugality on the consumables and fuel for such a heavy and fast bike.
K.N.M.