1971 Honda CB125S – Little ripper

Bike Profile

Jim Scaysbrook's restored Honda CB125S. More and more Japanese ultralightweights are appearing on the local scene. The bikes are relatively cheap to restore and generally require little intricate knowledge, workshop prowess or special tools.

Robust, attractive, reliable and frugal to own and run. What more could you want in a motorcycle?

Story and photos: Jim Scaysbrook

In 1970, while killing time prior to sailing for England to chance my arm on the scrambles scene, I took a part time job working at Bennett Honda, the NSW Honda distributors, housed in a converted Nissen hut on Gardner’s Road, Mascot. My duties were menial, simply assembling new Hondas ready for dispatch to dealers – a job procured for me by the late George Pyne, who happened to be the general manager. It was a terrific place to work. Out in the retail showroom on the main road Col Evans and Ric Andrews (rest their souls) flogged scads of new Hondas to a hungry public, and across the paddock in the workshop were blokes like road racers Barry Angus and Laurie Turnbull, with the Keed brothers, Ron and Alan, in the spray paint division. I just couldn’t put these bikes together quickly enough, such was the demand from the dealers, with trucks, utes and trailers arriving constantly, demanding more stock. Naturally the focus was on the glamour models in the range, notably the new CB750, the disc-brake CB450, and the 250 and 350 twins, but some of the biggest volume came from the little CB and CL100 singles, which sold like hot cakes. 

I never did take that boat ride to the Old Dart, because while assembling bikes I met Newcastle Honda dealer John Harris, who put together a plan for the two of us to open a dealership at Gladesville, which George Pyne helped to facilitate. Opening our shop in 1971 coincided with the release of the new CB500-4, and the uprated version of the 100, the CB125S and the SL125 trail bike. These latter two went out the door in droves, and they rarely came back. Bullet-proof, they were. The first model CB125S came in three colours; metallic blue or red, and a curious ochre yellow that only its mother could love. Compared to the then-current two stoke offering from Yamaha, Suzuki and Kawasaki, the Honda was very pedestrian in performance, but when stirred it went quite well. 

There are no real tricks to assembling a motorcycle as inherently simple as this one – it certainly went back together with far greater harmony than it had come apart!

The old saying, “familiarity breeds contempt,” could apply to the CB125S, because it went about its business so unobtrusively, and with such utter reliability, that its fundamental needs often went neglected. Tappets went un-adjusted, as did points gap and ignition timing, and oil went unchanged. Occasionally, when the supply of lubricant became totally exhausted or converted to paste by engine waste products after many tens of thousands of miles, the overhead camshaft, which ran directly onto the cylinder head casting, would nip up. Because the rear chain on the CB was totally enclosed, and out of sight and mind, it would run and remain dry for ages, wearing the teeth off the sprockets. You just could not kill these things. The SL model of course got an even harder life, flogged remorselessly around trails and on countless rural properties, where it was expected to perform its duties in kelpie-like, uncomplaining and totally stoic fashion. We would sometimes trade in SL125s that had never been washed or had an oil change since the day they were sold. Invariably the lights, indicators, mudguards, footrests and levers would be smashed or completely missing, the kickstarter and gearchange lever welded to the shafts in some fiendish act of woolshed savagery, yet they would be running, somehow.

The CB125 remained in the Honda range for fourteen years, with a few changes along the way. A front disc brake was added in 1974 (the CB125S2), and the engine enlarged marginally (from 122cc to 124cc via 0.5mm larger bore) in 1976. The battery/coil/points system gave way to CDI in 1980. Production actually ceased after 1982, but after a year’s hiatus, two small batches (with 12 volt electrics) were produced for USA-only in 1984 and 1985. 

A refugee arrives

Times change, we move on, and eventually I forgot all about Honda 125s, until one day about ten years ago I popped into the motorcycle shop in Bathurst co-run by former speedway rider Glenn McDonald, and piled in a heap of extremely tatty little bikes was a chuck-yellow CB125S, which Glen had just rescued from a nearby property. “If you ever want to sell that, please let me know,” I said immediately and with complete sincerity. “Sure”, said Glenn, and nothing more was spoken of it, until about six months ago. “If you still want that CB125 you can have it for what I paid for it,” said the voice on the phone, and a few weeks later it was sitting in my garage. 

The Honda CB125S as found and ready for a makeover.

My wife’s reaction was not entirely unexpected. “Erk! What a heap of junk. And what a revolting colour!” I assured her that beneath the vast layer of muck and solidified oil mixed with red dirt lurked a little gem, but she simply scoffed, “Yeah, right.” I must admit that this machine did indeed look frightful. It had been leaking oil from several places; the cylinder head, the kick starter shaft, the tacho drive and probably anywhere else that was not supposed to leak, and this oil had mixed, over the years, with the local earth to form a thick and dense layer that covered the engine and the rear half of the bike. And that was the good bit. 

The odometer showed 18,924 kilometres, but as the speedo cable was broken, there was no way of knowing just when this figure was reached. I ascertained early on during the disassembly process that this little Honda had never been apart, in fact I doubt that it had ever so much as enjoyed the luxury of even a basic service. Perhaps the only concession to kindness had been occasionally topping up the oil, but certainly never actually changing same; the sump plug bore no evidence of ever coming in contact with a spanner. I reckon I removed several kilos of the aforementioned crud before the metal could be exposed, and the process of removing the engine from the frame begun. 

Left: Oil tight? Not exactly. Right: The restored engine, clean as a whistle.

Very soon after my initial purchase I contacted former ace-painter Ron Keed, who has painted dozens of bikes for me and who is a self-confessed CB/CL/SL/100/125 tragic. “Best bike on the road,” said Ron with a note of conviction, “can’t kill ‘em with an axe.” He should know, he currently owns at least a dozen examples in various models. And he added, “Just let me know what bits you need, I should have them”; an offer I gratefully accepted. Ron also readily agreed to come out of retirement to paint my new acquisition, and he suggested, “do it red, they’re faster.” 

Back to the job at hand, and the extremely grubby disassembly process continued whenever I had a spare hour. The factory-tightened fasteners had secured an immoveable purchase in the preceding 42 years, and virtually every one of the original pan-head screws was buggered by the time I got it out. Almost inevitably, the kickstarter had been electric-welded to the shaft, so it was out with the angle grinder for that one. Eventually, the two engine side covers surrendered and the innards were laid bare for the first time since they vacated Japan in 1971. 

Left: Once the engine side covers were finally removed, the true extent of the internal injuries became clear. Right: Stunning simplicity restored. If the British had built an engine like this they’d still be in business.

On the right hand side lies the centrifugal oil filter, and after a typical fight I managed to get the three screws out to remove the end cover. “Hello, there’s another cover under here,” I thought, but this was in fact a solidified mass of alloy-impregnated oily gunk that had set rock-hard and totally occupied the cavity that was supposed to be home to clean, free-flowing oil. After removing the flywheel from the other side of the engine, the reason became clear. The cam chain was so completely clapped out that it had thrashed around and worn away two alloy bosses on either side of the bottom sprocket, which, surprisingly, was in reasonable condition, unlike the top sprocket, which was practically devoid of teeth. Despite the fact that there was no lubricant left in the engine save for half a cup of dense black sludge, the camshaft had not grabbed hold of its plain bearings, and although two of the three piston rings were broken, the piston itself and the bore were quite OK. My admiration for this brave little donk was growing. During this procedure I acquired a small sandblasting cabinet (see review in OBA 40) and this proved to be a major breakthrough in the crud-removal process. 

And so the process continued until the yellow peril was finally reduced to its components, but none gave up without a struggle. Both fork legs were rusted solidly into the lower triple clamps – the rubber-mounted headlight brackets hold water perfectly. When attempting to remove the petrol tap, the entire bottom fell out of the tank, revealing that it had been roughly fibre-glassed together at some stage of its existence. From the beginning of this adventure, I was determined to re-use as many of the original components as possible, save for the stuff that just wears out, such as the cam chain and its tensioners, rings, gaskets and seals. True to his word, Ron Keed came to the rescue with all sorts of good used bits from his stash, and much of the new stuff came from Bert Kingston’s BK Performance in Brisbane. Bert has one of the world’s largest stock of NOS Honda parts, and is certainly worth a call for any Honda restoration. 

Left: Front and rear brakes are the same size single leading shoe but work very well. Right: Standard Honda rear shocks look puny and have performance to match.

Well-finished wheels are the highlight of any restoration, and the assembly of these was once again entrusted to Ash’s Spoked Wheels in Brisbane, who also supplied the spokes. The original rims, and the few other chrome plated parts, were done in Sydney by Enware at Caringbah. Long-time associate and master restorer Steve Ashkenazi is well known for his uncompromising standards of perfection, and after a few unsatisfactory jobs from other platers, discovered this company and managed to convince them that there was a market for top-quality workmanship. The results are excellent, Enware using decent copper plating beneath the chrome to produce a surface that looks an inch thick. Being a bike originally built to a price, there are more cad/zinc plated parts than chrome, and these were done by Metal Restoration Surfaces at Smithfield, who always do top work. 

New speedo and tacho set was sourced via the internet.

Of course, there were some parts that simply could not be repaired or procured locally, and here I discovered that there is a thriving after-market business dealing in these bikes (and many other Japanese lightweights) throughout Asia, where literally millions of the bikes have been sold over the past half century. One of the best is a Taiwan web site called Vintage Avenue, which has an incredible inventory of parts for tiddlers from all four Japanese manufacturers. There were some major lumps that I had to source in this fashion; the front mudguard being one and the instruments (both smashed and not repairable) another. The former set me back the sum of $69, and the later – speedo, tacho and the mounting bracket – just $60. Astounding value. I had high hopes of saving the original exhaust pipe and muffler, but the moment this came in contact with the de-plating solution, it vaporised, so a new one was also sourced from Taiwan. 

Fully enclosed chain case ensures plenty of chain life provided you remember to lubricate it.

The rear chain, unloved and unadjusted, had chomped its way through the chaincase, but Ron repaired this in the process of painting the entire bike (and supplying a replacement petrol tank) in his fastest shade of candy red. The ‘125’ sidecover stickers came via the web, as did a complete set of cables, an air filter element, and the two little rubber mudflaps for the front and rear mudguards. Some parts, including the handlebars and switchgear, came up OK with just hand polishing, but one item that needed major surgery was the seat. This was entrusted to Tony O’Connor at Eldorado in Adelaide, and the process of its recovery from near death was recorded in OBA issues 39 and 40. The final assembly of the engine was done by Trevor Love of Surfside Motorcycle Garage at Brookvale. 

A new life

Slowly but surely, the pile of new and/or refurbished bits grew in my workshop, and whenever I could steal a few hours away from the editor’s desk I would gleefully tinker away. One of the first items to be added to the newly-painted frame was a set of tapered roller steering head bearings, which were obtained over the net from Pyramid Parts in Sydney. Remarkably, considering it had not run for at least 15 years, the carburettor bowl still contained fuel, or at least, what had once been fuel, but was now an acrid, gummy solution that had coated everything with black gunge. I am told an ultra-sonic cleaner, as used by jewellers, is an effective way to get rid of this sort of detritus from tiny jets and the like, but not having one, I had to resort to elbow grease and very fine wire. 

Top: Mufflers on the 1971 models resembled the CB500 ‘flutes’, but are now impossible to obtain. Subsequent models used the reverse-cone megaphone style. Above: The megaphone style muffler from the post 1972 model was substituted for the original fluted style.

There are no real tricks to assembling a motorcycle as inherently simple as this one – it certainly went back together with far greater harmony than it had come apart! And so came the moment of truth – would it start? Of course it would, second kick in fact. The first test run revealed nothing more serious than a few minor tweaks needed, and instantly reminded me of just how sweet these little Hondas are. The power is adequate without being overly impressive, but it has little weight to shift and actually motors along quite well. The gearbox is typically Japanese as it snicks through the range in silent harmony. The brakes also do their job well – the front brake is actually very effective, and the front suspension seems to soak up most road ripples without a problem. On the other hand, the rear suspension ain’t much chop. The puny looking Honda units were under-sprung and virtually devoid of dampening when new, and they certainly haven’t improved with age. Fortunately, the cure is simple – fit a set of locally-made Ikon units, which come in the correct length, fitted with 88/110 springs. They look similar to the originals, except for the chrome top cover, and for the sake of a much improved ride, I’m prepared to overlook the slight visual difference and will probably fit these prior to any rally-going next year.

Speaking of rallies, it’s no coincidence that more and more Japanese ultra-lightweights are appearing on the local scene. The bikes are relatively cheap to restore and generally require little intricate knowledge, workshop prowess or special tools. Handbooks and parts lists are readily available, as is the thriving after-market replacement parts scene throughout Asia. 

“Not quite as quick as my VT-R 1000, but lots of fun!” Sarah Hetherington puts the newly-refurbished single through its paces.

For the cover photography for this issue, we enlisted the services of the charming Miss Sarah Hetherington, whose usual conveyance is a Honda VT-R 1000 superbike, so she knows her way around a motorcycle. Despite having around 100 less horsepower than her big, brutal v-twin, Sarah agreed the CB125S was quite a darling! 

1971 Honda CB125S Specifications

Engine: 4 stroke single cylinder, single overhead camshaft
Bore x stroke: 56 mm x 49.5mm = 122cc
Compression ratio: 9.0:1
Ignition: battery & coil
Carburation: 22mm Keihin
Power: 12hp@9,000 rpm.
Torque: 8.9kW@8,000 rpm
Transmission: gear primary, chain final drive, 5-speed gearbox with wet clutch.
Suspension: telescopic oil-damped front forks, swinging arm rear.
Wheels/tyres: Front 2.75 x 18, rear 3.00 x 18.
Brakes: single leading shoe drum brakes front and rear.
Weight: 114kg
Top speed: 112 km/h

This article first appeared in Old Bike Australasia Issue 42.