Thursday 18 February 2021

Honda CB100N

I purchased my ’84 vintage Honda CB100N in December last year (as an impoverished student with L plates) whilst perusing that well known hiding place of bargains - the darkest corner of my local Honda dealership. The bike had done only 5900 miles and was "in excellent condition having been owned by a careful, mature owner." With that description in mind, as I could hardly see the bike lurking in the gloom, I paid the £470 asking price and went home to await the delivery of my new steed (at least the delivery was free).

Several days later the dealer arrived, handed over the keys and scurried off on my trusty old QT50, merely pausing to tell me what a bargain I'd had! The dawn inspection the next day revealed the so-called excellent condition - the tank was dirty, the back wheel and tyre covered in oil, the seat had a slight tear and the engine was a mass of corroded alloy, with the chrome missing from the inspection covers - not a good first impression.


Attempting to start the machine did nothing to elevate my opinion of the bike (or the dealer) - several hundred kicks and a lot of sweat later the beast stuttered into life only to die again seconds later, the result of a flat battery on "this carefully serviced machine" The first ride was a different story. It revealed a smooth, quiet and fairly fast little machine which would pull almost 70mph (a pace which seemed almost death defying at the time) and accelerate fast enough to keep XRi drivers awake. All was not joy and rapture, however, the front disc brake didn’t and the gearbox locked solid - it required much rocking of the bike to free it if the bike was stopped in fourth or top, and, thanks to the pathetic battery, the engine stalled if the throttle wasn't blipped regularly.


On arriving home I set about righting the various wrongs encountered. The battery was charged, the seat patched up, the corrosion scrubbed off the engine with plenty of emery paper and elbow grease, a good finish being obtained with some Autosol. Several buckets of hot water and some washing-up liquid later and I had quite a decent little bike. Close scrutiny had revealed nothing mechanically wrong with the brake - some things you've got to live with.

The next 1800 miles passed without incident, then the engine began to tick over badly, the revs fluctuating between 1000 and 4000rpm, adjustment of the carb slide height had no effect on the engine’s habit of dying suddenly at higher road speeds. Examination of the throttle mechanism showed a frayed cable, but this had no effect and cost £7.15.

Close scrutiny of the carb showed what appeared to be a stuck pilot jet adjuster screw. Carb removal revealed a whole catalogue of disasters held together with mega-bodging. The pilot jet had been screwed into its housing with such force that the housing had cracked and the head had been chewed off the screw - how it worked at all is a mystery, especially in view of the chronically bent carb flange, ingeniously compensated for by two O-rings glued together. After I'd drilled out the pilot jet (replacement £6.10) and straightened the flange by rubbing it on a sharpening stone, the carb seemed to function properly and has lasted for 4000 miles.

By 8000 miles the original FVQ shocks were on their third stiffness setting and felt like they wouldn't last much longer, but 2000 miles later I'm still using them rather than spending £40 on pattern replacements. At 9500 miles the original Bridgestone rear tyre was replaced, after much swearing, struggling with a Pirelli Mandrake at a cost of £30. I hope all this doesn't paint too black a picture of the bike, reading over it does give the impression of a bit of a bad buy, but this isn't the case.

The CB100 is easy to ride - being light and very manoeuvrable, gives 90 to 100mpg and has a top speed of about 68mph. The bike is very reliable (if left alone by bodgers) and has never really let me down. The spark plugs last for a long time, chain wear is very light (mine's like new after 10000 miles), whilst tax and insurance are the lowest possible, mopeds excepted.

The riding position is good for both touring and town work, being fairly stretched out and upright, but the seat is not much use, causing bum ache on longer trips. The handling and general performance is good around town, even on A-roads its performance is reasonable - the bike encourages you to ride just for the kicks.


The bike only let me down once. It happened as I was travelling towards a roundabout at about sixty, pulled in the clutch lever to change down and the lever shot straight to the bars with no resistance - I was terrified but managed a clutchless change in time to get around the roundabout. I then headed for home right away, fearing that a snapped cable could leave me stranded 25 miles from civilization. It later turned out that the clutch adjuster had unscrewed itself due to the high frequency vibration - still, at least I learnt all about clutchless changes!


The engine type, a OHC single cylinder four stroke was first developed by Honda in the sixties, and has a long history of reliable service, second to none. The main thing with these engines is to change the oil as often as possible - some people do it at as little as 750 miles - the rest of the maintenance though straightforward, can be ignored with a great deal of impunity, even if that leads to lots of new rattles.


All in all, the CB100 is a good value bike if you ca get hold of a good ‘un and I would recommend one to anyone who was considering a cheap-to-run learner or commuter bike, or was just looking for a little fun on two wheels. Would I buy another? Well, not now, a full licence and a new job being strong incentives to look for a decent 350 powervalve...


D.J. Peppel