Saturday, 15 October 2011

Honda CB250T


I wondered how the original shocks had survived 54000 miles and 15 years. I mean, they were shit the moment they came out of the factory and leaked away a few miles later. CB250T's were renown for a lot more problems besides, but how the guy had avoided riding right off the road with that dead back suspension beggered belief. As did putting that kind of mileage on an apparently original engine - the screws were as they came out of the factory, untouched by a screwdriver.

The motor still ran but acceleration wouldn't cause a Honda Melody any concern. The owner reckoned it was a classic in the making until I pointed out all the white smoke coming out of the engine breather. Blown pistons or burnt valves; maybe both! We agreed to differ on his £500 price tag. I left him my phone number, told him any time he wanted to accept fifty quid to give me a bell. Two weeks later the bike was in my hands.

I thought I might as well ride the gutless heap around for a while. I put some ancient Girlings on the back straight away. They were so far gone that they only worked because the springs were about twice as hard as justified by the Dream's 400lbs, the total lack of damping not being important.

The Dream had a slightly top heavy feel but seemed quite sound. The forks had gaiters, a brace and a stiffness that matched the back end - either rusted solid or half a dozen washers added to each leg. Potholes tended to be a horror story but I could forgive that as it went where I pointed it, was quite a snappy tool in traffic. The motor was only good for about 60mph but that was more than sufficient for the daily commute.

All went well for about three months and 1200 miles. Then the camchain rattled, the silencers smoked and the engine didn't want to do more than 5000 revs, which was a big problem as that was when the power began to slowly flow in. This was a sign that the whole motor was completely worn out; I wasn't surprised, only gratified that the mill had lasted so long. I'd expected it to seize up within days, the engine always felt like it was on the verge of failure.

The solution to my woes was a rebuilt Superdream engine out of a crashed bike for £75. I thought this a bit of a rip-off but there wasn't anything cheaper available that would actually run. The motor wouldn't fit straight in but a bit of hammering and drilling soon resulted in a running bike.

Superdream motors are quite reliable if rebuilt well, but at this kind of age it's all in the lap of the gods. My impression was that I'd got lucky. Acceleration was brilliant after the worn out motor, although brand new the earlier bike was actually more powerful. The CB sneaked up to 70mph then threw itself into a near terminal wobble but came out on the right side of 80mph with reasonable stability if gut churning buzzing. So much for its infamous balancer system.

Smooth, even stable, cruising was available in the 65 to 70mph range. Brief bursts of acceleration were possible if the circumstances became desperate. The art of riding the bike was to keep the revs between 5000 and 8000. Above that vibration was a real killer, below it there was sod all power and enough chain jumping in the taller gears to suggest that some teeth were missing off the cogs.

The chassis had received a lot of cosmetic attention. Resprayed bright blue and black it looked only a couple of years old. That concern hadn't spread to the chassis bearings, the new found turn of speed leading to their rumbling after about a week. I think the steering head bearings were original, totally lacking in grease and oval when they hadn't broken up. The swinging arm bearings were plastic rubbish that had cracked up, letting the spindle run wild enough to generate large score marks. Bits from a breaker had to suffice, along with loads of grease.

No sooner had I fixed the chassis than the balancer chain started to clatter. When I went to loosen off the bolt it'd seized in solid, a not uncommon occurrence on old Hondas. It's quite usual to snap them off when applying too much force, leading to an engine out stripdown! I sprayed it with WD40, retreated for the night to let it soak in. WD40 is amazing stuff that does much more than just revive electrics. I spray any bike I want to store, as it stops corrosion forming. The next day it freed off and I was able to obtain some more life out of the chain (they, along with the tensioner, last less than 20,000 miles).

The dumpy styling of the Dream I found attractive in a perverse way. Its utterly conventional layout harked back to the days when men were men and the vast majority of bikes were British. The riding position was ideal for lounging around in town on fine summer days. In the wet, vast quantities of water was thrown into my lap. Any prolonged attempt at speeding numbed my shoulders and sent my arse dead. Flatter bars would not have suited the forward mounted pegs and there was no way the gearchange could take any kind of linkage.

Old Hondas have notoriously fickle gearboxes. Superdreams are better than some, at least until the selectors wear out. Mine was dubious once past third with the sickening debility of jumping out of gear into a false neutral. The revs soared to destructive heights never envisaged by the original designers and most parts not welded to the frame tried to twirl off. The mirrors were no great loss as they only gave a very distorted image of my arms. I was rather more worried when the back wheel shook itself loose.

The flurry of vibes became worse when the valves were out of adjustment, a tedious business on these motors as there were three valves per cylinder that needed constant checking. The design used a single camshaft and a set of rockers that wore out quicker than either simpler two valvers or DOHC set-ups. There didn't seem any performance or economy advantages from the three valves; like the balancer it was more a marketing ploy than an exercise in good engineering.

I had to replace some rockers and valves twice, once after 6000 miles and the next time a further 7000 miles down the road. Parts were readily available from breakers but usually needed some work. The valve seats will take a couple of regrinds before turning to cheese. The camchain kept rattling but bodging the tensioner held it at bay for the life of the rebuilt engine, which turned out to be just over 18000 miles.

The trouble with these motors is that when they close in on 60,000 miles there's very little left inside the crankcases that can be renovated. Just about every bearing was shot, the gears mangled beyond hope and the pistons shattered, bits rushing around the motor to make sure that a cheap renovation was beyond any hope.

What should turn up but a crashed CB400T. I heard the motor running and went for the best bits of each bike. The engine turned out to be fearsomely fast, putting 110mph on the clock, which threw the inadequate chassis into some wild weaves, wobbles and wallows. I was shaking by the time I'd persuaded the single front disc to bring us down to 70mph.

I'd always found the brakes adequate but that was, I realised, because I rarely went above 70mph on the old engine and a few tumbles may've also bent the chassis a touch. I changed the gearing to suit the acceleration, making the motor top out at 85mph; much safer and brilliant in town as it'd burn off much bigger bikes if I revved into the red. It went so fast I often found myself hurtling towards cages far too quickly, which had me on the front brake so heavily that the forks twisted up and the tyre screamed. The overheated caliper and disc then required an hour or two to recover.

Vibes were also vicious at most revs. A thrumming ran through the whole machine, making much more than 25 miles so tiring that I had to take an hour's R & R to recover. I stuck to blitzing traffic in town.

The motor lasted for six months and 4000 miles before it blew up in a big way. As far as I could gather from the mess a con-rod had broken. Inspecting the rust on the frame revealed that some of the tubes had rusted right the way through. The rolling chassis must've done over 80,000 miles and had decided to call it a day.

That was the end of the bike as far as I was concerned. No way I was going to chance having a frame break up on me and good engines were becoming very rare in breakers.

Terry Jennings