Thursday, 23 November 2017

Yamaha XS500


[The pictured bike still exists at the time of posting this article!]

I bought the Yamaha XS500 vertical twin from my brother with 24000 miles on the clock. It was generally clean, ran OK and I paid him £300 for it. I was quite pleased with the bike and had many trouble free miles, mixed commuting, touring home and abroad, and going to rallies all year round. It was a C model, known in the trade as the oval port model.
 

The XS500 was first introduced into the UK in its B model form and came with twin front discs, wire wheels and chrome guards. That was in ’75. The cylinder head usually leaked oil everywhere as it was a two piece job - the rocker/cam box bolted to the top of the cylinder head leaking oil at its joint. It was never a serious threat as a separate oil pipe supplied the oil, it merely leaked out on its return. The later one piece head fits the early model and solves the problem (as long as you change the carbs at the same time).
 

The frame is the same but tank, seat and bodywork were restyled, along with different brakes and cast wheels. The C model had a disc rear brake which shared the wet weather lag with the front - solved by fitting Ferodo F1 pads (they’re also cheaper and last longer). Seizing up the calipers was not a problem as long as the bike was in regular use and the brakes serviced annually. All parts are exchangeable between models to a greater or lesser extent. The squarer tank and seat of later bikes will fit earlier models with a bit of modification to the brackets. Though the clocks look identical to those on the RDs the gearing is different.
 

Lighting was rubbish. The easiest and cheapest way to cure this was to take a trip to the nearest car breakers. Sealed beam units are dirt cheap and fit straight into the Yam headlight. The stock unit just scatters its meagre 45 watts all over the place. I eventually fitted a Cibie Z beam unit with a halogen bulb -- the best light I’ve ever had on a bike. The tail light is fitted with two double filament bulbs, nice and bright and no worry if one bulb has decided it’s had enough.

The C model was the quickest of the four models produced. The only change to the D engine, other than an easier method of balance chain adjustment, was to make the exhaust ports round rather than oval. On the C model it was necessary to remove the generator cover to adjust the balance chain whereas the next model had a small porthole fitted. The D model had new carbs, inlet stubs, air filter box and automatic vacuum petrol taps. The E model runs both hotter and leaner than all the others, so one grade hotter spark lugs are in order -- the E model) goes slower than the others.

Some XS500s seem to expire early, but if it's got more than 20000 miles on the clock it’ll probably keep going up to around 50000 miles when minor engine work is necessary - new balance chain, reground valves. Camchains can last a lot longer than that and bearings, pistons and bores seem not to wear unduly.

The B and C models were good for 120mph, the D model 115mph and the E model only 105mph. The easiest way to improve the last model is to fit earlier carbs. The fuel consumption reflected the performance, 50mpg was the norm on earlier bikes but I’ve had 70mpg on the E model.

The engine is a DOHC unit with four valves per cylinder and looks very complicated. In reality, it’s one of the easiest bikes that I have worked on. The valve actuation is by forked rockers, adjustment by allen key and spanner - they rarely need doing. The balance shaft chain tension also rarely needs doing, again adjustment is by allen key. Ignition timing is as easy as most Jap bikes - adjust the points and line up the marks when the bulb goes out. Most of these adjustments were done at 4000 miles with the oil changed at 2000 miles. Most of the time they didn’t need doing and the checks were extended to every 6000 and then 8000 miles.
 

One of the few problems with the XS500 is its sensitivity to exhausts. There are not many after-market systems that work as well as the standard system, itself heavy, complex and quick rusting. Don’t even think about a 2-1 as either the top end or bottom end power will disappear. A Campbell replica is the best bet. Handling, as standard, is reasonabIe. You are very much aware of the mass of the bike.
 

Most of that weight comes from the engine. After much experimentation I found it necessary to increase the damping at the front end - this was done by using 50% 20/50 oil mixed with 50% fork oil. The standard back shocks soon wear out, becoming hot and bothered on bendy back roads. S & W’s sorted that out. Handling then became taut and very, very stable.
 

The stock tyre sizes are 3.25x19 at the front and 3.50x18 at the back. I tried various tyres and ended up with Dunlop TT100s. But I soon found it was worthwhile to go up one size to 4.10x19 and 4.25x18. Then Arrowmaxes appeared on the scene, so I fitted 100/ 90 at the. front and 110/90 at the back. These were by far the best tyres I’ve tried, they really suited the bike. Like a lot of Jap bikes, the XS500 is very funny about its tyres. No doubt, I could have spent a lot more money on very flash tyres, but the Arrowmaxes were available at discount prices, which made them a good buy. Tyre wear averaged around 9000 and 11000 miles back and front respectively, although on long hot summers with a lot of scratching thrown in that became 6000 and 8000 miles.
 

Brakes were more than adequate, pad wear averaged 12000 miles at the front and the back ones go on for ever. On paper, the engine power may not look very impressive, but the low down torque is very noticeable when riding, so although it is red-lined at 9000rpm, you tend to change gear very early - 3000 to 4000rpm. This seems to give the engine a very easy life. There is quite a power step at 5000rpm, so you can still have fun red-lining it. There are different sprocket sizes available for the gearbox and wheel, so you can change the gearing to suit your particular riding style - usual gearing equates to 80mph at 6000rpm. Very lazy stuff for a 500.

My XS500 started out as a C model, but after many miles it had various D and E parts fitted. It is still in regular use, although after many rallies, touring trips and clocking up 69150 miles I parted with it. I still see the bike and it now has 73534 miles to its credit.

Worn parts? Well, shortly after getting it I neglected to check the valve clearances correctly. One burnt out valve and seating later, it was cheaper to replace the head with a second hand one than to buy a new valve and reseat the head.
 

The carbs started getting messy at 50000 miles so I fitted some later ones I had kicking about. I reground the valves at the same time and fitted a new balance chain. The camchain is still standard - it’s a ruddy great double row job and will probably outlast the rest of the bike.
 

The XS500 does look a complicated old girl but is surprisingly easy to work on and service. The motor can be stripped down with only one special tool - a bolt type puller which just happens to have the same thread size as a tow bar bolt - Halfords, two for 98p; These bikes can be picked up for around £250 in fair condition and then tailored to suit the rider. My experience tells me they can be made to go on and on. I got rid of mine for a Suzuki 650 Katana, but then that’s another story.
 

Stephen Bergman

No comments:

Post a Comment

Note: only a member of this blog may post a comment.