Sunday, 6 May 2018

Honda CB125S


TAN 26N was bought in the summer of '84 for the princely sum of £100. On arriving to look at the bike, it appeared to be in good condition for the year with both chrome and paint still in evidence. The engine looked good externally with no visible oil leaks or signs of butchery.

It had no MOT or tax but according to the owner had recently been rebuilt by him. This last point made me a little suspicious. Why, if the bike was in such good condition for its age, hadn't the owner put a years MOT on it and another £100 or so on the asking price? I decided to give the beast a test ride.

I started the engine first kick and listened for any unusual noises from the 125cc OHC single cylinder engine, in particular the cylinder head. If oil changes are skimped on these machines the head is easily ruined due to blocked oilways allowing drying up of the camshaft bearings. If this happens a replacement head is needed and costs more, new, than the bike is worth secondhand.

No nasties were evident as it ticked over evenly and quietly. l took it for a spin around the block and everything appeared fine. It pulled well throughout the rev range in all the gears and seemed lively for a four stroke single. That was it, I decided to buy it.

It failed the MOT, according to the tester the frame was out of alignment. This pissed me off excessively, with visions of the machine being a write off due to the expense of frame replacement, especially as the rest of the bike was good.

l took it to another MOT tester where it passed with a compliment about it being in good shape for its age! I put the bike through another three tests in the time that l owned it and all it required was—a new exhaust.

Servicing was simple. Just change the oil every 800 or so miles and check the tappets at the same interval. Usually, no adjustment was required but when it was, patience was needed as adjustment is a little awkward. Two thou is a ridiculously small gap to set accurately. Each time the gap was set and the locknut tightened, the gap invariably went down to one thou or disappeared altogether.

Perseverance is the answer as it is important with such a small gap to set it accurately. Ignition timing is dead easy to set and rarely seems to go out anyway. In all the time I had the bike (about four years), I only ever bought one replacement spark plug. It just never seemed to wear out.

Performance for a 125cc single of its age was quite good. if wound up in the gears, acceleration was quick enough to out accelerate most cars in the city and it cruised at 60mph without having to thrash it (I prefer whipping myself anyway). Top end was a bit over 70mph. One had to be careful of artics breathing down one's neck. When this occurred I always felt that this great hissing monster was about to devour me (well, at least it makes life exciting).

Headwinds took their toll on performance with the bike having to be worked hard to maintain a high cruising speed. Starting was always a one kick operation. The bike always lived outside, and no matter how freezing cold or wet, the CB never failed to start and warm up quickly without fuss. This used to give me a perverse form of pleasure as I listened to numerous cars in our roads churning their engines over and over on cold winter mornings. 2CVs seem to be particularly prone to this activity in cold weather.

It was light enough to hold upright when slides started by just sticking both feet down and praying hard. I never came to any grief so I must have been doing something right. Generally, overall handling was not good. On bumpy surfaces the suspension felt far too soft and when rough surfaces were combined with bends at any reasonable speed, all sorts of unwanted contortions took place. Modern 125s show just how much suspension has improved since this machine was made.

Lighting, however, is another story. Although the electrics were always reliable (never any problems with flat batteries, etc), the power of the 35 watt headlamp left a lot to be desired. Even in poorly lit streets I found the beam inadequate for safe riding much above 40mph.

I considered fitting a higher wattage light bulb, but on looking at the electrical specifications I found that the total alternator output was only 45 watts. A bulb of any higher wattage would not leave enough power for the ignition and rest of the lights. As it was, the engine would sometimes stall on tickover when the headlamp was on and indicators in use whilst waiting at junctions for any length of time.

I can only assume that the drain on the system was such that the voltage dropped enough so as to stop the coil producing an efficient spark. Once riding along there appeared to be no problem except that the headlamp beam dimmed significantly each time the indicators flashed. Later models had, 75 watt alternators which must have improved things a lot.

Braking also left something to be desired. Brake fade from the front SLS drum was noticeable. Locally, this was particularly apparent when speeding down Grapes Hill in Norwich and the lights turned to red at the bottom. The front would start to fade when applied hard although the rear held up well. This also seemed worse in hot weather. It seems that the cooling of the linings must be the problem here. However, at least the braking was unaffected in the wet.

Given that l was not a high mileage rider or used the brakes particularly hard, the life of the shoes seemed rather short. This was true for both pattern and genuine parts. I always cleaned out the drums and made sure that all the spindles were lubricated so as to ensure the brakes were not binding on. I can only assume that this must be something to do with the lining quality.

I finally sold the little Honda just before Christmas last year for £200. Not bad considering that I only paid £100 for it and got four years of basically trouble free use from it. My reason for the sale was that I finally got round to passing the bike tests and wanted something with more zap. I ended up with a rebuilt air cooled RD250 which certainly fulfils the zap department. However, it has recently cost me more money in parts and running costs than the Honda ever did. I still see the bike around the city and it appears to be going well and still looks in good shape. The bloke that bought the Honda never even bothered taking it for a test ride. He looked it over, listened to it running and said, ”It sounds like a good 'un," and handed over the £200.

Would I have another? Yes, if I were to use it just for commuting to work, but since I also like a bike for entertainment purposes I really want something with more performance. A Honda CB125S is an excellent and inexpensive way for someone to get into biking provided that a good example can be found. In many ways I found it a rewarding machine to own and hope that it gives its new owner the same service it gave me. 

Steve Crook

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