On UK roads, thanks to our rotten winters and thirty-odd years of abuse, Honda CD175's are becoming very rare. A whole generation of bikers who really have no idea what one is... to clear that up, it's a little vertical twin of the simplest, single carb, OHC construction. Its main demand, 500 mile oil changes to stop the gearchange becoming completely impossible; at best it's a very useful anti-theft device, helped along by cold engine clutch drag that will stall the motor if the front brake isn't held on when first gear is engaged.
I have often been tempted to bung some BSA decals on the side-panels, try to pass the bike off as a classic Brit. Doubtless, BSA zealots would respond in rage with a large sledgehammer and my pride and joy would soon be a mess of metal. Where these big Brit twins are limited to around 75mph by their inherent teeth shaking vibration, the little CD sports a similar top speed, though a strong gust of wind or steep incline will reduce that to a rather dangerous 70mph. Big gaps in the gear ratios in the loose four speed box don't help matters any.
In theory my bike is a 1973 model... however, during its long and arduous life – mileage unknown as speedo's are not long-lived and far from essential in this kind of biking – it has been fitted with a few different engines and a collection of cycle parts. Much to my wife's annoyance, in the garage there is an array of about twenty CD's in various states of disrepair, mostly dismantled. It just sort of happened like that – I'd be riding around minding my own business or parked up somewhere when some guy would start making furtive gestures at me; the next thing I know I had arranged to collect some non-running CD175. There are maybe hundreds, perhaps thousands, of defunct CD's stashed in people's garages and gardens.
I can't bring myself to throw anything away as I am sure as soon as I do I will need it! I don't think I have ever bought a set of tyres for it. Chains invariably short-lived but replaced in a similar manner. With fuel around 60-80mpg, this all works out as extremely cheap biking. Oil changes take about ten minutes (beware of rounded sump bolts...) and doing the valves/points about half an hour (every two weeks). The only thing the engine does demand is a new set of plugs every three months, or so – can be ignored but starting progressively becomes more difficult, rather than the one to three kick affair with the motor in reasonable shape. I have managed to break two kickstart springs, a bungee cord works as a temporary replacement.
Camchains are a bit notorious on this make but I find leaving them alone for around 5000 miles isn't a problem – and then a quick tweak on the bolt (prone to thread stripping). I bought half a dozen new camchains from a dealer who was closing down and tend to fit one every 20,000 miles, though I have done twice that without any problems. Camchain breakages write off the top end, possibly a false economy.
Disintegrating silencers can lead to rather large gaps in an already loose powerband and gunshots on the over-run, they are patchable until they actually fall off! It may be the relatively quick demise of the exhaust system, and notoriously miserly nature of CD owners, that leads to burnt out or sticking exhaust valves, or just plain old throttle abuse – on major highways the CD needs to be ridden flat out to stay out of the way of traffic.
The first sign of this will be smoke out of the exhaust on the over-run, not to be confused with smoke out of the breather pipe which is usually piston rings on the way out (shouldn't happen until 40k). Caught early on, a cylinder head dismantle, cleaning up and lapping in of the valves may well suffice. There are plenty of signs of top end problems and no way it should catch you by surprise.
Unless oil changes are really neglected, things like crank bearings should out-last the rest of the bike – the crankshaft a hefty four bearing design that makes the average two bearing British twin crank look ridiculous. Vibration only a problem when the bike is held flat out... even then it's a relatively minor buzz that does no damage to the machine, more the little bike telling you to back off a touch than a sign that it is about to blow up.
If the silencers are in decent shape and performance is more constipated than expected – 17 horses so don't get too excited – may well be an air-filter clogged up with road dust. They usually end up with a couple of holes added, often slashed by screwdriver wielding merchants – replacement with a newish airfilter mesh can transform the nature of the beast.
Another possible area of concern, the clutch pushrod's oil seal can be ruined by its proximity to the final drive chain (or the whole caboodle ruined by a snapped chain), leading to rapid loss of oil. You may want to take the cover off to check its condition – decent owners replace all the cross-head screws with allen-bolts, as the former tend to corrode into the cases (one can imagine a paranoid Mr Honda, after experiencing Brit bikes, designing them that way to stop them falling off).
Overall, ease of starting and relative usability of the gearbox will give a good indication of the actual state of the engine. New spares are now difficult to obtain but there are plenty of dead bikes hidden away as a source of free or cheap spares. Rather like the British bike scene thirty years ago. In another thirty years I may well have the last running CD175!
At this kind of age some deep-seated wear can attack the chassis, things like the wheel hubs and forks can end up in a rather dangerous state... it has to be said that the SLS drums, even when brand new, were not up to much and even slight wear/neglect can leave them in a dangerous state. The same can be said for the suspension, basically a set of pogo-sticks at each end that can make the bike feel like it is falling apart on rough roads.
This is one area where my stash of spares is virtually useless! But a modified set of Girlings meant for a CB350K3 and a complete front end off a BSA A50 have totally transformed the dynamics and feel of the CD175. I can't understate the effect these mods have had on my riding enjoyment of the beast! The frame itself is a reasonable trellis, although a decent set of swinging arm bushes needed rather than the stock rubbish.
Light in weight and nimble by nature, the suspension upgrade really lets the bike shine, the only limitations found on wet roads when the on/off nature of the stock rear drum can leave the tyre squealing and sliding – but it is something I soon became used to and quite amusing to make ped's jump out of their skin when leaving the braking to the last moment on crossings! I overdid it a couple of times, ended up sideways to them! At least the huge mudguards give adequate protection during typical British winter weather.
The CD, even when abused through the gearbox, isn't a fast accelerating machine, having trouble getting away from some of the sportier cars and being put in its place by MZ250's and the like! Once wound up to 40mph it does spring forward to about 65mph when it's then a real effort to extract maximum velocity. Its most natural pace, around the 60mph mark which makes for some fear on the open highway when cagers tend to run over rather than around the little twin!
Another frightening element of the machine, its 6V electrics make for a front headlamp right out of doomsville, more a matter of sitting on the tail of a car on country roads than actually using the light to see where you're going. Worse yet, the battery is invariably short-lived and needed to start the machine from cold even though the CB175's electric start was deleted. So bad was this element of the machine, I paid for an alternator upgrade plus new regulator/rectifier and, of course, 12V bulbs. I now have the choice of running a powerful front light and suffering a battery that goes dead in fifty miles (the light using more power than the alternator can produce) or squinting with a barely adequate halogen unit. Oh well, can't have everything, can ya?
Commuting, the machine fits well into the pace of city traffic with excellent comfort and very low running costs. I do about a 120 miles a week with nary a problem although the bike gets a good fettling twice a month. Odd things begin to happen at this age, like the fuel line falling off due to brittle plastic or the seat's bracket breaking off due to rust; an eye needs to be kept out for potential problems.
If it can corrode it will, and I ended up with polished engine cases and stainless steels silencers, amongst over niceties. Take a bit of pride, apply some tender loving care, get a stash of spares, and this is the kind of bike which will keep on running and running!
Gerry E.