Tuesday 7 December 2010

Honda CB175


The lines of the small Honda twin defined a certain era of Japanese engineering, when plain and simple would do, when motors were expected to excel merely on the back of jewel-like efficiency rather than an excess of valves, cams and electronic trickery. Much simpler than the CB175's OHC vertical twin engine things don't get.

This one was a real mismatch, a hybrid thrown together from various defunct CB's but nevertheless quite close to stock. Its best point was an untouched engine that was supposed to have done slightly less than 20,000 miles. The owner showed me a clock with only 19,800 miles on it, but it could've come from anywhere.

The clue to its relative state of mechanical newness, a gearchange that still worked without an excess of false neutrals. It wasn't exactly slick but compared to the 47000 mile CB125S that I'd arrived on it was a precision affair despite the similarity in the two machine's ages.

I don't know if it was the same in a new bike, but the CB175 didn't really want to run below 5000rpm and only really got going once wound on past 7000 revs. Though the engine was similar to the infamously durable CD175, the addition of hotter cams and an extra carb changed the unit out of all recognition.

The CB175's need for revs explains why so few are seen, these days, on the road. Unless meticulously maintained (as in every 500 miles) the exhaust valves burn out. The single carb CD175, in contrast, is just a good old boy plodder designed to be almost impossible to rev beyond seven grand.

Even more likely, worn gearboxes, cause the rider to miss a shift, sending the revs wild, tangling the valves or mashing them into the pistons, with easily foreseen consequences. The five speed CB175 box even more temperamental than the four speed CD's.

Piston ring and camshaft bearing troubles are more potential hassles but usually down to poor lubrication causing overheating. 500 mile oil changes very necessary to keep these engines in prime condition, partly because the oil is shared between gearbox and engine, any debris from the former on the fast track for the top end of the motor. This era of Honda wasn't equipped with an easily exchanged oil filter.

I bore all of this in mind when checking the bike over. If the valves or pistons are on the way out, it's usually shown up by smoke out of the engine breather pipe. Worth checking both the clutch pushrod seal and the nearby crankcase area for cracks (from a chain snapping).

The former isn't a major job as the old seal can be whacked out and a replacement found from a bearing factor - the worry is that the oil has leaked out, the engine run on a dry sump, causing all kinds of mayhem - though even that doesn't take out the hefty crankshaft!

Couldn't find anything wrong with the motor, even the electric boot still worked. The frame was a touch dubious, looking a bit twisted from certain angles. But the wheels lined up so it had probably been straightened back into line at some point, though not by an expert.

The bike handled as expected, a touch twitchy on the cheap tyres but not much effort needed to control it and a general feeling of good stability. After the comparative rigours of the CB125S that wasn't hard to achieve, its frame not that far off a push-bike trellis.

The only disturbing thing revealed from interrogating the owner was that fuel was awful, 45mpg (I was used to 100 plus mpg on the CB125S). Not so much an indication that the engine was worn out as that the mill needed to be continuously revved to get anywhere fast. I decided to go for it, offered 450 notes against the 750 demanded by the owner. Mine for 500 quid after the mildest of haggling sessions.

Picked the bike plus a large quantity of spares up the next day. The first ride, some speed testing on the dual carriageway. Revving hard through the gears the Honda rowed along splendidly until the clock hit 77mph when it went into a vile old speed wobble. An old hand, I loosened my grip on the bars and it died out.

Turned out to be swinging arm bearings about to die a death. Talk about bad timing. Fortunately, there was a usable swinging arm, bushes and spindle in the cache of spares. I say fortunate because I ended up smashing the swinging arm and spindle into an interesting shape. Not wanton violence but the only way I could get the rusted up mess apart.

Back on the open road, the Honda screamed up to 83mph when fierce vibration set in, causing me to back off to a relatively smooth 80mph. No sign of smoke out of the exhaust, not even on the overrun (a sure sign of shot exhaust valves, worth checking when going pillion on the test ride). The bike felt much happier at 9000 revs than it did at 3000rpm, pretty typical of Honda twins of this vintage and the inverse of their small singles when heady revs were accompanied by jackhammer vibes, one of the few areas where the CB125S excelled.

Whilst the speed wobbles were now absent it tended to squirm rather than run through corners, feeling like it was on two mismatched tyres. Increasing the tyre pressure helped a bit but I didn't want to spend out on new rubber until the tyres were down to 1mm. As it wasn't actually suicidal in the wet, decided I could live with it!

Fuel was actually closer to 50 than 45mpg, still pretty pathetic for a 20hp machine with a loud (as in rotted) set of silencers. The TLS front drum was a peach of a stopper - strong yet sensitive; but then I was used to the SLS abortion on the CB125S. Apart from a reluctance to run at low revs, there wasn't anything really bad about the bike and a lot that was good.

After a bit of a sort through the spares, a respray of the cycle parts in the original blue, and a heavy polish of the alloy and chrome, the bike was placed in MCN at the absolutely bargain price of 999 notes. Sold her for 895 smackers within three days.

I'd done nearly 5000 miles in three months, just scouting through the splendid English countryside in the summer. Soon became used to the bike's handling in the corners and the way it needed to be strung out at maximum revs all the time. It was the latter that had me slightly worried - just how long would the precious motor last? Better safe than sorry, there were always pastures anew just around the corner.

S.L.

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After seeing about a dozen machines this little red Honda twin turned up. 22000 miles despite being 20 years old and having endured an excess of owners. This one had been stored for a while as it wouldn't start, but there was not much corrosion and it looked complete and original. £100 was demanded but I talked him down to sixty, with tales of having to pay hundreds and wait months for spares to turn up. Pushed the bike three miles home with a grin rather than grimace on my face.

I had no idea what was wrong with the motor. It kicked over okay, although the battery was flat so the electric boot just clicked. The Honda has 12 volts so the first step was to connect up a car battery after putting some new oil in the engine. The white sludge that reluctantly dripped out of the sump wasn't too impressive. The motor churned over on the starter but didn't fire. I checked the plugs, they were black with carbon, giving a faint yellow spark.

It wasn't until the next day that I was able to buy new plugs. These gave a faint blue spark. The CB has points ignition so that was the next step. There are timing marks so a bit of wire with a bulb and battery was all that was needed to set the ignition timing. First, though, I cleaned up the points and set the gap dead on. With perfect timing the spark was a bit stronger. The motor still didn't start but made some encouraging noises. I had a spare condenser from a car so I replaced the old one. A big fat blue spark.

It still wouldn't start. I had to take off the carb bowls and clean all the gunge out. By then the car battery was flat, so I had to resort to the kickstart. Fired up first prod. I reconnected the bike's battery, fired her up again and was all set for a quick spin around the block. Lovely! Well, I had been hacking around on a 60,000 mile RS125. The tyres had cracked sidewalls so there was no way I was going to get an MOT until they were replaced. I also had to replace the puny swinging arm bearings, as the arm was waving all over the place and put a new battery in as the old one wouldn't hold a charge.

Total on the road cost was £125, which turned out to be a bargain. I know some people knock old Japanese bikes but it really was a neat bit of design. A simple OHC vertical twin engine, developing an impressive 20 horses. Despite the lack of balance shafts it didn't really vibrate any more than a newish Superdream; indeed, I found I could burn off a friend with a CB250N which had suffered a similar mileage. His alloy and paint were in a worse state than mine!

The Honda had a classical simplicity to its lines that, to my mind, made it rather more attractive than the Euro-bland Superdream. I used to annoy my mate no end by racing with him, as the CB175 was lighter, could be banked over further and responded better to my desperate body language. Ultimately, the smaller twin couldn't quite match the other bike's 85mph top speed, but the Superdream needed a mile long straight to get past 80mph, which the CB175 could match.

About the only area where it was deficient was the gearbox. There were supposed to be five speeds available but I was only ever sure of getting into second and fourth. The change from first to second was so treacherous that I usually took off in second with a touch of clutch slip. The second to third change went okay, initially, but the box would bounce out of that gear without any warning so it was a good idea to hit fourth as soon as possible.

The gap between second and fourth was quite large, which meant that three or four thousand revs could quite easily be lost. The engine was happy to run at low revs but below 6000rpm there wasn't much by power. This may have partly been down to rotted exhaust baffles and a holed airfilter. To ride fast the engine had to be caned into the red in second and a double shuffle on the gear lever up to fourth done as quickly as was humanely possible. Done right this would drop the revs to 6500-7000, which was exactly where the motor burst into power. I wasn't that surprised to be getting just 50mpg!

The OE shocks had long been junked in favour of some stiffer units, but the front end was a bit elastic. Nothing a decent pair of springs wouldn't cure but as the Honda only weighed 300lbs it was easy enough to keep under control. Helped by a large TLS front drum that could twist the forks under hard stops and needed to be treated with care in the wet. The back drum wasn't too sensitive and didn't seem that powerful. Overall, though, it was quite an easy package to manhandle just about everywhere.

There were a couple of problems down to its age and the need for steel to turn into rust. Most worrying was the petrol tank. There was so much crud that the reserve filter in the bottom of the tank was permanently encrusted. No amount of cleaning would make it work. The underside of the tank was speckled with rust spots. The guards were also half rusted through and paint was flaking off the frame at the welded joints.

For about six months and 7000 miles all I did was change the oil, check the points and valves, and tweak the camchain tensioner. The drive chain wore at a ferocious rate, ended up with a couple of links taken out. The tyres didn't seem to wear, a trait shared with the brake shoes.

Then, with just over 29,500 miles under its wheels, there was a lot of misfiring in the exhaust and somewhat constipated performance. At first I thought it was just the silencers rotting through but after applying some Gum-Gum to the holes the poor running wasn't improved. A local garage did a compression test; way down.

I was not amused by the camchain. I'd been told I would have to drill out a couple of rivets to split it. After I'd done that I found it had a split-link further down the run. It looked a bit ropy so I bought a new one (with a split-link). The problem with the engine was burnt out exhaust valves. After waiting a couple of weeks, the dealer handed over a set that were too big. He wouldn't give me my money back! Or even tell me what they were off so I could try to sell them.

I located a seized engine for £25, found the whole head was in good shape so just bunged that straight on. Whilst I had the engine out I replaced a couple of gearbox seals that were dribbling oil and had the cases bead-blasted. I swapped selectors between engines in the hope of improving the gearbox. The motor went back together without any traumas, I even got the valve timing right first go. There was a lovely mechanical rustle when it fired up that indicated I had done everything right. Not bad going, considering it was the first four stroke I'd ever built and the Haynes manual became annoyingly vague at important points in the reconstruction.

Top speed was 83mph, all five gears could safely be engaged and fuel consumption improved to 55mpg. There was a little bit more vibration when riding flat out but nothing too worrying. It would cruise in the 70 to 80mph range, depending on conditions, with winds or hills making it faster in fourth than fifth. I often ended up using the pillion pegs when cruising fast, as the forward mounted pegs meant for the rider were a bit cramping, strange pains developing in my thighs after half an hour. The seat was one of those soft/hard jobs that had the rider squirming around after about a 100 miles, when given the lack of working reserve it was time to stop for fuel.

The bike wasn't ideal for long distances, then, but with a bit of tolerance on the rider's part it was possible to cover a few hundred miles in a day. Its best point was the feeling of having an unburstable engine that could be flogged relentlessly for hours on end without worrying about it blowing up. They built these old Honda twins very tough as evidenced by a CD175 I bought for spares.

The CD only has one carb and no electric start. The clock read 79000 miles and I didn't think the engine was going to start. After putting in a new fuse, charging the six volt battery and cleaning the carb, the old dear surprised me by firing up on the fourth kick. I put the CB's numberplate and tax disc on, then took the bike for a quick blast. The four speed gearbox was terrible but the CD bounced up to 75mph without too much work and seemed to run okay. The chassis was dangerously rusted, but I was sufficiently impressed to do a quick renovation job.

If anything, with its strange styling, reminiscent of a sixties BSA twin, the CD175 has more character than the CB. It's certainly more relaxing to ride, with a stately feel where the CB demands to be ridden at its limits all the time. With a fully enclosed chain and 70 to 80mpg it's a much cheaper way of doing the commuter chores and a big windscreen looks perfectly in character, whereas the CB would look plain silly.

The CD now has an incredible 92000 miles done and is still going strong, although there's no telling if it's on the original engine or not. The CB is approaching 49000 miles and judging by the smoke out of the exhaust it's going to need its first rebore soon. I've found there are a lot of near wrecks around that can be persuaded back into life without too much financial pain, so they may well be the ultimate hacks.

Peter Bowden

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The deal took some doing. The old man's immaculate CB175 was the target of my lust. I dropped a few lines about him looking like an elephant on a fly. And 20 years on one bike must be getting boring. And wasn't the engine getting a bit rattly. It wasn't, not even with 37000 miles on the clock. 500 mile oil changes and religious servicing had proved wise investments. I passed the test on a GS125 and sold the bike to a friend who also wanted to get into motorcycling. The old man knew what I was after but being a good sport he eventually gave in and bought himself a new CB500 twin. The CB175 was mine.

For those ignorant few who don't know about them, the CB175 was a prime piece of learner tackle back in the early seventies when youths were allowed to ride 250s of whatever power the manufacturers could safely extract. Yamaha had the RD250, Suzuki the GT250 and Kawasaki their infamous 250 triple, whilst Honda ploughed a lonely, if successful, path in the form of four stroke OHC vertical twins, ranging in capacity from 125 to 350cc.

The CB175 shared much of its engine with the infamously indestructible CD175. Honda added sharper cams, an extra carb and an electric start. 20 horses were claimed, backed up by the bike's ability to put 80mph on the clock on a good day (ie the first day I had the Honda). The old man rarely went above 60mph, not giving in to the little twin's high revving nature. It's an engine that absolutely thrives on revs, only limited in its fluid nature by the nasty five speed gearbox that not even loads of tender loving care from the old man could temper. He reckoned the gearbox was an acquired art; I thought it was just a nasty piece of excrement.

Even compared to the thumper delights of the GS125, the CB thrummed away quite heavily. Judging by the beaming face of my father the new sophistication of his 500 had alerted him to how out of touch he'd become with modern motorcycle engineering. My brief taste of the bigger bike left me amazed at its velvet feel. But after a few weeks the 175's vibes went into the background, only really annoyed when I went deep into the red in the lower gears.

Highlights of the first couple of months included an 80mph, flat out, motorway drone, stopping every 80 miles to fill the tank up; bouncing the bike through the bends on its stands to keep an RD350LC from overtaking (the antics probably scared him off), and getting the Honda up on one wheel in the High Street - quite inadvertently, officer - which resulted in the chain snapping half a mile from home! The clutch didn't like it, either, slipping for the rest of the week, though it still dragged when stone cold. Snapped chains could break the back of the crankcases, but mine just left some scar marks - if you see any oil leaks around the gearbox area take the cover off to check.

The old man couldn't understand why the chain had broken, it was only 9000 miles old and had been lovingly treated with Linklyfe. One advantage of having a fanatic in the family was that he insisted on doing the 500 mile services himself, leaving me free from worry. Servicing consists of points, valve clearances, carb balancing and camchain tensioner, plus the oil changes. Nothing too difficult, or so it seemed to me as I looked over his shoulder. I got nagged because I didn't clean and polish the bike every day but it was a small price to pay for a free motorcycle.

The bike had a pair of Girlings out back, stronger springs in the forks and a sensible riding position right out of the sixties. That meant it was an easy bike to throw around in town, a joy in the back lanes and yet not uncomfortable to cruise flat out along the motorways. The saddle could've done with thicker padding, my bum complaining after about 80 miles, which coincided with the range. Fuel was much heavier than the GS125, 40 to 50mpg depending on the throttle abuse. The old man reckoned he could get 65mpg, but then he claims 70mpg from the CB500, which he rides like a pensioner (probably because that's what he is). The GS, even when heavily thrashed, still turned in better than 100mpg. On the good side, the bike neither leaked nor consumed any oil between the frequent changes.

After three months of riding the CB175, I managed to persuade a girl on to the back. Neither of us were particularly heavy, but our combined mass took its toll on the Honda's performance. Acceleration was slow enough to have cagers trying to run us down, whereas solo I'd had no trouble burning them off up to 50mph. The handling also went rather squirmy, the babe complaining that the bike felt like it was falling apart. I ignored her hints about getting a cage, wasn't that surprised when she went off with a Metro owner.

The Honda never seemed quite the same after that experience, perhaps I was becoming too used to it and able to handle all it could give out. As I had no money of my own I couldn't move on to something bigger, had to make the best of what I had. The summer of 1997 I loaded the bike up with an excess of camping gear and headed for Scotland. The great adventure, the open road...bloody hailstones and incredible rain!

The CB added to the amusement by cutting down on to one cylinder, coming back on with its full power and generally skidding all over the road. I thought about turning back but rode through it. I used the motorway to eat up the miles. About 500 miles in a day. Just as we crossed the border, the darkness of night descending, the top end of the engine went into machine gun mode. It sounded like the rockers were breaking up. I bowed to the wisdom of my father, who'd insisted on paying for AA coverage. Especially when I pulled over to find that the motor had blown all its gaskets and was spewing out oil and fumes! Looked like I'd melted the bugger, with 46000 miles on the clock.

Back home I had to endure a lecture along the lines of the bike lasting for over twenty years before I got my hands on it and done for the poor thing. After the expected tirade, it was revealed that a hundred quid CD175 engine had been secured and would be fitted over the weekend. And it was. The cunning old bastard left me with a machine slower than the GS125, which died a death before high revs could be achieved, so mildly tuned that it's impossible to thrash it. Meanwhile, the CB175 engine's being rebuilt but I won't be allowed near the finished result. No justice in the world, is there? To be fair, they were great machines in their day, still have their uses.

F.R.

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The motorcycle was an L reg Honda CB175 with 15000 miles on the clock in a very clean condition. My father told me about it, and at first I was horrified that it might be the plain Jane CD175, but the CB had class looks, twin carbs, 20hp and electric start. The power was unbelievable compared to that of a sports moped, a slow progressive build up to max power at 10500rpm with a top speed which would nudge the 80mph mark.

I rode the bike for 11000 miles during my year of ownership. It had a few little bugs. A slight weep from the cylinder head gasket that never became worse. On one run back from Kent it started running on one cylinder - I eventually found the cause, a blocked reserve pipe in the tap, a common problem.

Riding home from college, without a care in the world, the bike suddenly died on me. A fuse had blown - a rummage in a nearby dustbin found a fag packet and some silver foil but it started burning as soon as I turned on the ignition. A long push home followed. A loose wire in the headlamp was eventually found.

I had three punctures in a row, the last coming as I was leant over at a racing angle, the back end hopping across the road in a frightening way. Another long push home. The sharp end of a spoke was eventually found to be the cause.

The bike was relatively cheap to run. Between 60 and 70mpg, meagre oil consumption and cheap insurance compared to the 250s. The performance could not match the two stroke twins, which always meant I was last to arrive anywhere. On long hill climbs the lack of engine size meant that the engine had to be knocked down a couple of gears.

The bike had been fitted with trials type handlebars which made motorway riding a bit tiresome.The quality of the paint was excellent, especially the frame which is more than I can say for today's bike. The chrome also stayed in good condition.

A year with the bike and I was hankering after something bigger. I was taken with four strokes and the reliability of Honda and part exchanged the 175 for a Honda 400/4. I was given the same money I had paid for the bike by the dealer I purchased it from a year before. My impression of Honda reliability was soon to be shattered but that's another tale.

E.N.Chudley