Monday 10 January 2011

CZ 250 Twin


We all have our motorcycling dreams. The £50 CZ 250 twin was far from mine, more like a nightmare on wheels. But for fifty quid what can you buy? It was better to be back on the road than legging it everywhere. Even if I was the centre of ridicule and laughter. A CZ twin has the same credibility as a Honda Melody.

The first problem was obtaining an MOT. New swinging arm, wheel and steering head bearings were knocked in. The rotted silencers were thrown into the dense undergrowth that passed for next door's garden. They were so rotted they'd fallen off when I'd given them a good kick. As there weren't any stands I was able to convert the downpipe into a 2-1 on to which was welded an extra bit of pipe that exited into an RD250 expansion chamber. Quite!

The engine needed new points, new plugs and a carb clean out before it'd deign to start. There ain't much compression but the world's most awkward kickstart makes up for that. It was often easier to push-start, as the stripped down form must have weighed only 250lbs. The crackle out of the spannie was most rewarding, though the motor only worked between 2000 and 6500rpm!

The electrics were the final hurdle. The battery was as dubious as a Russian nuclear station and the wiring a mixture of black wires of different thickness, some off a car loom, the others household wires. The sole fuse was a nail. The engine ran but nothing else worked. A new battery, new wiring and used Jap switches solved most of the electrical problems long enough to get an MOT.

Riding back home with the lights on had the motor coughing away like a dog barking. The battery wasn't charging, the control box was dead but I found another bike for £20 with a seized engine. Old CZs are amazingly cheap. Once that was fitted, the rather meagre front lamp worked as best it could given the generator's minimal output.

The bike had quite wide cow-horns, but it was still a heavy slug to throw around despite the lack of mass. The bars and pegs were quite comfortable for town work. The seat was a massive refugee from something like a Gold Wing, was thus very comfortable. The seat was the only item not affected by the vibes, the bars and pegs buzzed as the revs rose until by the time 6500rpm was hit the bars were difficult to keep a hold of.

The two cylinder stroker was claimed to make 17hp but I found top speed was only 70mph. It was just as well it didn’t go any faster because the bike wandered all over the road as if the frame was bent! This was because the frame was in reality, after whipping off the tank, er, bent! The underside of the tank was also stained with rust.

A weekend was spent mixing and matching the two bikes' best parts to end up with one reasonable machine. The models were about five years apart but the engine lined up with the frame as if they were made on the same day. Probably a comment on the level of development put into these bikes.

With a straight frame, the handling wasn't half bad for an old Communist hack. Indeed, the chassis was good enough to handle their Rotax engined model. The suspension was so stiff that any lack of damping didn't really matter, the main limitation on bend swinging was the fixed footpegs grounding out, which tended to jerk the machine around. A wrench on the bars pulled her back on to line.

What was a little disturbing, was the way it'd react to the inevitable pot-holes in town. My arms and arse took a real battering and the front end was shaken way off line. A fearful wrestling match with the bars ensued on particularly rough sections of town tarmac. I found it was safer to ride as fast as the engine would allow, as the bike seemed better able to float over bumps.

This, however, was markedly dangerous for the simple reason that the ancient drum brakes were about as much use as wearing a cheap watch on the vibratory old heap. Okay, the shoes and linings were not far off being worn out but that didn't seem to excuse the excessive muscle needed before they started to grip even mildly. Many a time I was thankful for the demonic crackle of the expansion chamber, which at least warned cagers of my impending appearance. The horn had immediately expired after the MOT examiner had tested it. I didn't miss the pathetic squeak.

The best that could be said for the drum brakes was that they were so mild in action that they were fine on wet roads. Which was just as well because the Eastern European tyres had a special teflon coating that made them turn wet roads into ice-rinks. Judging by the way they refused to wear they were probably decades old, original equipment! One of the stranger aspects of the old rat was that it'd slide quite controllably, even taking to a bit of a countersteering without flopping over. It probably had fond memories genetically implanted in its steel frame of glory days carting around a sidecar. There was no way I'd fit a chair with the pathetic stock brakes!

There were some other hassles trying to use the bike as a mere commuter. The most prominent was the way the plugs would foul and the associated smokescreens. At one point it got so bad that some coughing cager rushed out of his car and started whacking the top of my helmet, screaming incoherent abuse. Before he busted my ancient lid, I let out the clutch and roared through the red light, leaving him eating my exhaust fumes. It's important to have plenty of oil going through the engine, otherwise the marginal main bearings will start knocking.

Spark plugs lasted less than 1000 miles. I always carried a spare set so that when the motor oiled up I could do a quick swap. Then I'd clean the old set-up at my leisure. This plug swap happened every day if I forgot to clean the motor out with frequent bursts of acceleration or about twice a week at best.

On one occasion I was so infuriated that I rushed a plug swap, ended up cross-threading the plug. It went down okay but on the last turn just kept turning around. Surprisingly, it got me home with just a bit of gas escaping past the plug's washer. The compression ratio was so low that it didn't really matter. There was no way I could extract the plug, even with the head off, but the head from the seized engine was useable after I'd cleaned off all the carbon. Decokes were regular, 500 mile events unless I was willing to tolerate a top speed of 30mph. It paid dividends to tweak the points at this mileage, which was about all the regular maintenance I had to do. The engine was easy to work on, seemed to have better quality alloy than the Japs. Whilst the motor was apart I put in a new set of rings as the old ones looked like they were about to crack up.

Fuel and oil were the only great expenses - 50mpg and 100mpp. Anything else that went was replaced with cheap stuff either from the breaker or from my spare bike. One of the curious aspects of riding around on the CZ was that quite a few people approached offering me their old, broken or crashed, bikes. I ended up with three of the damn things which I got for free, two 250 singles and one twin. All I had to do was turn up and push the things across town.

The singles both had wrecked main bearings, the twin had a piston crack up and subsequent crash damage when it'd run off the road. I had enough consumables to last me a lifetime, so I thought I might as well make another bike out of all the bits. A running 250 single engine was obtained for £25 and some cunning hammer work had the second bike on the road in just a weekend.

The single was freer revving, good for about 75mph but put out significantly more vibes at 60mph. No, I preferred the twin, sold the single off for £125 without any trouble. That inspired me to renovate the other two bikes, making about a hundred quid's profit on each occasion, not bad for a few days work. I started putting ads in newsagent's windows, picking up about half a dozen various models.

The neatest scam was putting 125 engines in the larger chassis, re-registering them and selling the bikes for about £200 a time. The 125 was dog slow but tough enough to learn on and could then be sold on again for a similar price. Everyone won. A lot of the bikes I bought had minor problems with the naff electrics that were cheap and easy to fix if you knew what you were doing. There are lots of bargains around.

Back to the 250 twin. They are very basic hack transport that costs next to nothing to buy and not much more to run. They need a bit of rider involvement to keep running and the motor's a bit agricultural. The chassis could take some Jap mill as a cheap project bike but for God's sake fit some proper brakes!

Alan Whitehaven