Monday 6 February 2012

Yamaha SR125


I suppose there really was a SR125 under all the modifications. Some cretin had put an extra yard, or so, in the front forks. A dubious looking seat left the pillion about a foot above the rider, who had to grapple with massive pull-back bars that threatened to take chunks out of his groin. Something that defied comprehension as the owner had the kind of beer gut that kept the brewers working overtime. He offered to take me for a ride but I didn't believe the SR could withstand our combined mass.

Riding it solo revealed that the front end wobbled and the whole thing quivered. The only point that interested me, though, was the 12,500 miles on the clock and £375 price tag. The low mileage on the four year old machine was down to the difficulty of riding it any distance, as much as the awful looks. I reckoned most of chop bits could be exchanged in the breakers. £350 changed hands and I motored home slowly enough to avoid falling off.

It really was an utterly horrible device, both in looks and rideability, giving me a few heart attacks as it would suddenly veer off in a direction of its own choosing. I rather hoped I'd get in the garage without being seen, but a couple of curious neighbours turned up, making sarcastic remarks about my becoming a Hells Angel. I'm sure that turning up on such a bike would have resulted in a serious beating from the Harley mounted merchants of doom and death.

So, to work then before anyone else found out what I'd bought. The breaker supplied a front end off an AR125, a seat off a GS125 and a few other bibs and bobs. Total cost £75. Most of the parts were persuaded on with nothing more than a bit of drilling and hammering. Luckily, the chop forks were the same diameter as those from the AR, just as well as the yokes certainly weren't interchangeable. After a weekend's work the SR looked more or less normal and was ready for some serious riding.

The Yam has a disturbingly old tech single cylinder engine that Honda would've had no trouble churning out in the sixties. It doesn't have much power, but then neither do most 125s. It plodded up to a useful 70mph then turned the mirrors fuzzy and had the back wheel snaking all over the place. Pushed hard it would just touch 75mph.

The AR125 forks were a steadying influence and the singular disc reassuring in both power and feedback. The front end worked surprisingly well with the rest of the chassis. The flat handlebars I'd fitted were a bit too flat for comfort and their angle not quite right for my wrists during town commuting. Otherwise, it was a most useful device for commuting back and forth to work.

A week later I'd fitted a handlebar off a CD175 which was much better suited to my arm length. The forward mounted rests were not to my liking, so I persuaded myself to make up some moderate rear-sets. I already had a rose-jointed gearchange linkage that fitted on to the shaft, so all I had to do was cut down the linkage and rethread one end. The only thing I had to buy was some alloy plate, not expensive as it was a bit of off-cut from the local metal merchant. I spent many a happy hour carving the alloy to the required shape.

The result was a perfect riding position, the trick being to make arms and thighs lay parallel to each other. Unfortunately, the merely adequate SR gearbox had become a bit vague when operated through the linkage. Second to third quite often threw the box into a neutral, as did coming down from fourth gear. Despite being a mildly tuned single, there wasn't a lot of punch at any revs, the only way to make the Yamaha shift was to play havoc on the throttle and gearbox. After about a month I became used to the sensibilities of the box, eliminated most of the false neutral.

The real neutral could be a bugger to find in town traffic and the clutch would drag like there was SAE10 oil in the engine instead of Halford's cheapo 10/40, the oil changed every 2500 miles and not using a drop between changes. The low seat height meant my legs had a fighting chance of resisting the bike as it crawled forwards at junctions, but it quite often stalled just as the lights were due to change. This became so annoying that I put in a new set of clutch plates, but the drag persisted. A new clutch cable made the action ten times more progressive.

Just before I did the clutch change I attempted to wheelie the SR. A huge dose of revs, dumped the clutch.....the front wheel came about an inch off the ground and the motor sounded like it was turning into a metal grinder. Attempts at wheelspins were equally disappointing, although it may have been the stress of these that contributed to shot rear wheel bearings at a mere 14,800 miles.

That occurred about 50 miles from home, causing me to ride down country lanes on a bike that felt like it was falling apart. It was the nearest I'd come to an accident on the Yamaha, caused by the bike hopping over towards oncoming traffic. Wrestling desperately with the handlebars didn't make one iota of difference to its suicidal instincts. A brief burst of throttle got me across the bumper of an oncoming car, left the Yam slithering over the grass verge until we came to a halt. I'd almost broken both legs holding the deranged machine upright.

The wheel spindle had thought it fun to seize up, didn't take much notice of my battering it with a huge hammer. A friend pointed a blow torch at it whilst I heaved away. I clouted it so hard that the bike fell over on my friend who was waving the blow torch around as if he'd set alight to the machine. The potential inferno could quite easily have taken out the house. After about another hour's worth of physical abuse the spindle was finally out. My mate had given up on the blow torch, had managed to whack his thumb and ended up leaping around, ranting and raving with a litany of curses. I almost pissed myself at this sight, which wasn't well received when he regained coherence. The spindle had a lot of surface rust but cleaned up, so I got away with just a set of bearings.

To recompense my battered friend I took him for a weekend's jaunt from London to the Lake District. We probably looked a sight, weaving in the slow lane of the motorway, but the sun shone the whole weekend and we sunk enough beer to turn a ship full of sailors drunk. Handling two-up on A-roads wasn't up to much, the suspension seemed down on its stops and every time I banked over the chassis was shook as the stand hit the deck. B-roads were even less fun as we both ended up bruised from the bumps, and so shook about from the wallowing that when we stepped off the bike we rolled around like drunken sailors for a few minutes.

Any attempt at overtaking cars was fraught with danger, the SR's mediocre acceleration turning slug-like even with vicious use of the throttle and gears. We almost caused mass carnage in one overtaking manoeuvre, when the gap I was aiming for simply ceased to exist. Only a cager willing to brake and swerve violently saved us from extinction.

Even under such abuse, fuel consumption was about 70mpg, 80mpg being nearer the mark for most riding. In the 8000 miles I've done nothing else needed replacing. This frugality adds to the fun nature of the SR, despite its obvious performance limitations, the fact is I can just leap on to the saddle and ride, without worrying about whether or not I can afford it.

One time I thought the engine was cracking up, it felt like the crankshaft bearings were falling out. Turned out to be a loose camchain that was fixed by whacking the adjuster with a hammer. The tensioners do stick, the resulting noise obvious to all but the most mechanically ignorant. Engine maintenance takes about half an hour every 2500 miles. Much simpler singles than these there ain't.

I would've preferred a more road orientated chassis - if I was paying silly money for a new 'un I would've gone for a GS125 - but they can be cheaply modified to a more useful spec, even if they end up looking a little strange. As long as there's a decent set of tyres on the wheels, they can be thrown around with all the zest that any other 125 can take; they are light in mass and low in power; a vicious bit of handlebar wrestling usually pulls the bike out of trouble. As I said, fun!

Eric