Sunday, 13 May 2018

Yamaha XS250

SOU 312S, a silver example, first appeared on a front drive a few streets away. Having been replaced by a CX500 the XS250 was in a poor state. Left parked, several months rain took its toll and each time I passed the house with the dog, it looked worse, but l still thought it would make a good replacement for my Suzuki GT185. When I finally found the owner at home, on the sixth attempt, he said l could have it for a tenner as it was only fit for scrap.

The only good points were a decent pair of Roadrunners, the rest was dog rough... the motor was solid so I convinced myself that the kickstart was at fault. Removing the right-hand engine cover revealed a perfect kickstart mechanism. the damn primary gear would not turn.
Left-hand cover off, the alternator would not budge either. Off with the cambox cover, the camchain had to be sawn through, the head removed to reveal the left—hand piston melted into the bore. The piston was eventually freed from the bore using impact technology.

An engine was purchased from a breaker which had a sound top end and the best bits of each motor were combined, complete with the odd helicoil and bodge. The frame and cycle parts were resprayed, both discs skimmed, a caliper replaced from the local breaker along with many other items and a wheel not about to crack up installed. It looked really great when reassembled.

I liked its simple lines. It was a very straightforward piece of design work - a SOHC vertical twin with pistons moving up and down alternatively, not a balance shaft in sight. It had conventional twin rear shocks, cast alloy wheels, discs at each end and an air of ruggedness.

It spluttered into life but was obviously not right. The carbs were cleaned out but the main bearing and big-end shells were making a bit of a row, so these were replaced and the motor reassembled again. It ran nice and quiet, passed the MOT first time. First problem was an unreliable tickover, the bike needed much fettling every 100 miles as the timing kept going out.

Performance was not startling. Although it could be run along at low revs the power didn't start to appear until the upper reaches of the rev range, and even-then it would not pull your arms out of your sockets. Top speed was somewhere around an indicated 90mph, it was much happier cruising at 70mph, where it would buzz along all day without much of a care in the world.

Handling on worn suspension was fair, it never seemed likely to throw me off in the curves and save for the odd bit of weaving or wobbling when the road surface deteriorated was stable enough to be pleasant on motorways. I never rode the bike to extremes as I wanted to maintain my grip on life.

After about 1500 miles I dropped the bike exiting the M4 roundabout with my teenage son on the back. The shame of it. Cuts and bruises, ruined jacket and scrapes on the bike. I couldn't even have a good swear with the lad about it. The gear lever was bent and jammed but the following cars stopped to assist and get the bike off the road. A borrowed adjustable wrench straightened out the gear lever and the motor fired up okay. The cause of the fall was an oil slick.

I fixed the bike up easily enough but I had lost confidence in it. An Avon Supreme front tyre and a new set of head races helped instill some bravado in my riding. The points kept wearing out rapidly and I had to re-time it every weekend - I thought this was only necessary on old British iron - but at least the miles were piling up.

I was doing 1500 mile oil changes with a new filter at 3000 miles. The chain was washed in petrol/paraffin then boiled in Linklyfe every 1000 miles, sprayed every weekend, along with a couple of strokes of the grease gun to the two swinging arm nipples. Both sets of pads were dismantled every service and reassembled with Copaslip. EBC pads were an early improvement and covered 5000 miles before being transferred to the rear with the new set on to the front. 

At 31500 miles, 7000 on the rebuilt motor, I bought a new engine from a school that had been given two by Yamaha for a project. At £100 it was too good to miss. It still had the need for frequent ignition timing adjustments. Piranha ignition at 36300 miles gave a much crisper motor with better throttle pick up. Plug gap had to be closed to 0.025 to cure a cold misfire at tickover.

A few weeks later I replaced the other Roadrunner. The Supreme on the front was placed on the back and a Michelin M388 was fitted to the front. The Roadrunners did about 5000 miles each, the front Supreme had done 7000 miles without significant wear The bike was really running well, I believed the problems were behind me and I could start planning some long runs without the need for constant maintenance. Comfort was OK for a 100 miles at a time. The seat was the first to give problems, not helped by an imperfect body posture resulting from forward mounted foot-rests. If you wanted to ride flat out for long distances the bike would quickly become very tiring.

I was able to swap from four to two star fuel with no ill effects once the electronic ignition had been fitted. The bike averaged 80mpg which I thought very reasonable. even a hard ride down country lanes didn't dent it too much, with 72mpg being the result. One up for lack of balance chains, eat yer heart out Superdream owners.

One dark and rainy night in March '89 as I’m plonking back from Salisbury across the plain, doing about 50mph along a nice curvy bit the bike loses power... the rear disc had seized on. Slackened off the master cylinder pushrod, the brake freed off and the journey home continued. A weekend strip down revealed a soft seal ring and some corrosion on the piston. A new seal and polished up components appears to have solved the problem.

Some useful suggestions for users -- Motocraft Ford plugs (AG22C) work fine, cheap against NGK; Ford 15W40 oil, good and cheap; Piranha ignition, well worth the money; Avon 180 Supreme tyres, good grip, last well and inexpensive, M385 ditto; EBC pads much better than stock; Baja foam grips soak up the vibes nicely.

To conclude, if you are prepared to invest a little time to maintain and service the beast I don’t expect anyone to be disappointed in an XS. Cheap and cheerful with a plentiful supply of parts, both used and new, you can still pick up a runner and another for spares for next to nothing. Worth looking out for.

Derek Anstey

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