Monday 7 September 2020

Yamaha XJ650

Bring on the madmen. Weird shit XJ650. The owner was the local nutter, an RD400 fanatic. But the XJ650 had barely turned a wheel. 1983 machine, 11000 miles, nicely burnished with age. RD riders don't take kindly to shaft drive four stroke fours. This guy had done the odd tour but barely touched the surface of the bike's abilities. He wanted a grand for the ten year old machine and I wasn't going to argue with him, was I?

70 horses, 450Ibs, 653cc, DOHC's, eight valves, nice build quality plus conventional suspension and frame. The shaft drive the only surprising element of the compact machine that had a perfectly natural riding position. Power delivery far from frightening. I was at home right away. Nice stately, secure feel from the chassis, slow turning but secure nineteen inch front wheel.

Twin front discs on the remote side. SLS drum to the rear an on/off device. 4-2 exhaust roared away, suggesting the baffles blown or removed. The clutch was heavy and the gearbox crunchy. The shaft drive fluttered a bit when I made a change. Universal joints on the way out? Nah, just naff engineering. It cleared up as speed increased and I got a handle on the clutch/gearchange co-ordination.

The first spot of rain fell. The clouds let loose in anger. I smiled smugly, already fully togged up in the waterproof gear. The front guard designed to throw up an excess of road spray. That soon collected around the HT leads. Stutter, stutter, stutter; a tune I didn't want to hear. The XJ tried life as a triple and a twin. Could've lived with that but not the way the power would suddenly switch on. Not nice, on greasy roads and with a direct shaft drive.

Made it back to the mansion in one piece. First step, spray with WD40. Test ride. It worked! Second step, buy a decent front mudguard to keep the rain at bay. That worked, too, WD40 no longer needed. In contrast, the rear guard was better designed, innocent pillions not sprayed by water in the wet. The bike still picked up an exceptional amount of road grime even during the mildest of trips. Made the shareholders of Gunk happy. Quick action kept the chassis in shape.

What would it do? 125mph top end. Only in favourable conditions, mostly it ran out of puff at 115mph. There was a nice slug of power between 70 and 110mph in top gear, no need to play like a racer on the box. Relaxed high(ish) speed cruising was a piece of cake. Even comfortable, despite being naked, at 95mph for an hour or two. Acceleration was on a par with a friend's CB500S up to the ton. Thereafter the four had the legs on the twin, much to the latter owner's dismay.

The XJ was quite lowly slung. Easy to dig something in on fast, bumpy bends. The first time it happened, caused a bit of a shuffle and a near heart attack. Often it felt less than its apparent mass but when something went wrong it felt rather heavier. Hard to keep under control. It didn't like to be braked going into corners. Or to have the throttle rolled off. Bit like a BMW, worked best when set up on its line and gently accelerated through the curve. A minor miracle that the mad RD rider hadn't fallen off.

The front discs were quite nasty. Not lacking in power, as such, but operating in an apparently random manner! They defined wet weather lag despite running EBC pads and not being noticeably scored. The brake fluid was an odd colour and viscosity. I only found out after drilling out the bleed nipples. The calipers full of gunge, reluctant to come apart. Goodrdige hose the final part of the renovation.

Improved feel, stronger stopping but the same dangerous lag in the wet. Inconsiderate engine braking had the back wheel hopping and skipping as the shaft chumed through its bearings. The back drum was full of asbestos dust; the linings had cracks in them. Had to send the wheel off to be relined, plus new shoes.
With all that fixed the back drum became a big softy that helped me pull up safely in the wet.

The only way around the front brake hassle was to keep gently squeezing the lever to clear off the water from the solid discs. Many times I was tempted to take the Black and Decker to 'em. In the dry, they were able to squeal the tyres. Only if I took them apart for a clean every 5000 miles, or so.

The original suspension was showing signs of age. The back end had a slight ton-plus weave from shocks that lacked any discernible damping. The forks would shake coming out of bends or on fast bumpy roads. Koni shocks, used and cheap from breakers, sorted the former. Didn't touch the latter until the damping went and the steering head bearings became all loose.

At this point, it dawned on me that a whole new front end was the ideal solution. A Zephyr 1100 was deemed a possible donor bike and various breakers annoyed. Ended up with a ZR750 front end instead, which was probably better matched to the XJ. With that fitted, the braking was brilliant - twice as powerful and three times more sensitive. Handling precision was also improved but it liked to fall into slow speed corners. Maybe there was a slight difference in fork length or the increased travel upset things. Overall, well worth the ton and a half cost.

There's along tradition amongst UMG readers, just change the oil and twist the throttle. Until something goes wrong. After paying out for two top end check-ups in no real work, I decided to join in. Did an oil change every 1000 miles and a carb balance every 10000 miles! Had the valves checked every 20000 miles but they didn't need any work. Total mileage on the clock came to 79000 miles, with more to come. At that stage, time to trade-in!

If the engine was as tough as they came, the chassis was a different ball-game. Do note, that I wasn't really a throttle to the stop merchant and I did those frequent oil changes. I know people who've blown up XJs in less than 40000 miles. Mostly through total neglect of the engine. The way the chassis rots doesn't really encourage an excess of tender loving care. Not just the XJ650, also the 550 and 750 versions.

Was actually offered a couple of non-runners for less than a hundred notes each. Tempted, until close examination revealed very little that could be salvaged. The first component to die on mine was the exhaust system. By the time the baffles were completely burnt out, small holes appeared where the pipes joined up. Three hundred quid the local dealer reckoned for a new replacement. Didn't know if I should laugh or cry. Oddly, the front section of the exhaust was still in reasonable shape. Retained that, a new section of tubing cut and welded to match the old. A pair of universal cans clamped on their ends.

Many Yamahas of this era had somewhat finicky carburation. Change the exhaust system, flat spots appeared in the power output. Fortunately, these mods didn't affect the power delivery of the 650. Probably because it was mildly tuned for its capacity. Fuel was the same as always, around the 45mpg mark regardless of how the throttle was abused.

Next in line for self-destruction was the petrol tank. First evidence of this was a reluctance to rev high. Rust in the fuel line starving the motor. Kept on happening, the sides of the tank going very thin. Finding a replacement tank was a major achievement, took two months of plaintive phone calls! By the time the bike was ready to sell, that one, too, was ready to die!

Even more worrying was some deep seated rust around the steering head. Wire-brushing, primer and paint - it lasted for less than a month. This rust spread like wildfire throughout the frame. By 50000 miles I was riding around on a bike that seemed to be undergoing a metallurgical change! Only thing for it, strip right down, shot-blast and powder coat. That solved it!

By then I had to do all the chassis bearings. The cast wheels were very hefty but didn't want to release their bearings. They were also covered in a thick layer of corrosion, making me wonder how much metal was left. Not wanting to crack the wheels up, had to give them a going over with the blow-torch before doing the chisel and hammer blues. The bearings then popped out, albeit reluctantly. The wheels were also shot-blasted, painted and polished, covered in lacquer.

After all this effort, ended up with the best looking and running XJ650 in the country! That glory hid a set of electrics that was falling apart as I rode along. A complete rewire, newish switches and black boxes needed. I reckon everything would've had to be done again if the bike was going to make it around the clock. Apart from the motor, which needs frequent oil changes to survive, the long term build quality is very poor!

The used market is very variable. My bike fetched just under a grand on trade-in, which was pretty good going given its mileage. Predictably, the dealer clocked it back to 14000 miles and put it up for 1200 notes! The best bikes in the country won't cost more than a grand, you could maybe bargain that down to 750 quid. For 500 sovs, you should be able to buy a strong runner needing a little bit of tender loving care. Running rats go for less than 200 quid. Certainly possible to get lucky, give ‘em a look over. 

Dave Roach