Using a Yamaha RD500 stroker as a commuter machine might seem a little strange, but I had to sell the car to raise some cash and couldn't sell the RD for anything like what it was worth to buy something more sensible. Somehow, the 500 never made it as an obvious upgrade to the incredibly popular 350 - maybe big strokers are never going to make it or maybe its V-four motor was too complex to appeal to the masses. With 80 horses fighting 400lbs it was quite flash for 1985 but, these days, small beer.
One look at the motor gives the impression that it’s more complex than even a V-four Honda four stroke. A huge array of plumbing obscures the engine and promises lots of hassle if anything goes wrong with the beast. There are two separate cranks which both drive the same shaft through gears, which holds the clutch on the other end. Both reed valves and YPVSs are employed to optimise the power output of the engine.
Perhaps surprisingly, the motor is not particularly peaky. What limits its appeal in town riding is the very tall first gear, which makes it very difficult to do wheelies and involves lots of clutch slip when riding slowly. Although in the race replica mould, the actual riding position is quite moderate and the seat thicker than it looks. Most of the pain from sustained town work comes from my clutch hand, which, anyway, went away after about six months of such abuse. As long as the spark plugs were changed every 3000 miles there was little evidence of the engine clogging up in sustained slow speed work.
The worst that happened was a temporary cloud of blue smoke when the throttle was finally wound open. Usually, the normal two stroke haze was missing helped, no doubt, by using Silkolene oil. On the RD500 it’s very important to use high quality oil and to keep a check on the oil level, hard riding will get rid of a litre of oil in a couple of hundred miles!
RD500 engines do take out their main bearings - either because of poor quality oil, lack of oil in the tank, high mileage (mine has done 44000 miles and is still on the originals) or massive race track abuse. The knocking noises and vibes are pretty obvious when they go. Like on the 350s, the power valves can stick, but I've always given mine a bit of maintenance, so they are still OK... the power valves can be adjusted to alter the revs at which they take effect, so to a certain extent the motor can be de-tuned for town work!
One problem I have noticed, a little bit of wear in any of the cables upsets the power delivery out of all proportion. I’ve had lots of banging in the exhaust because the carbs have been slightly out and I thought the end was nigh when one of the power valve cables twisted neatly around another pipe and cable. There are so many cables feeding into the engine it looks like some Heath Robinson creation done on a particularly zany day.
I do about ten miles across London twice a day on the bike. The RD is narrow enough to get through most gaps in the traffic, but steering lock is limited and stops the bike doing ninety degree turns through small gaps in stagnant traffic. The very occasional bit of clear road is taken at maximum throttle. Unfortunately, rapidly losing speed makes the front end wobble quite violently... something that is repeated on the open road. After a while I became used to it, the wobble soon dies out and only does damage to the rider’s peace of mind. No amount of playing around with tyre pressures or type made the slightest bit of difference.
When I used to do a lot of fast riding I fitted Metzeler tyres but their quick wear rate (2500 rear and 4000 miles front) didn’t seem justified in slower town work so I ended up with a pair of cheapo Pirelis, which lasted over twice that distance. The Metzelers had about three times the grip in the wet, so I’m not sure which was the better value!
There wasn’t such an easy cure for the chain, I just bunged on the cheapest one I could find every 4000 miles and neglected it something wicked, as lots of TLC made absolutely no difference to its longevity. I never did work out the life of the pads as the calipers or discs always needed replacing before them! The twin discs were very powerful when they worked, which wasn’t very often... calipers seized, discs wore at an astonishing rate and even the threads that held the calipers started to strip. Luckily, the calipers were common to other models in the range, so it was a relatively cheap thing to sort out. The rear disc, strangely, didn’t suffer to anywhere near the same extent, and was so sensitive I only rarely locked up the back wheel.
The main cause for concern in commuting was the way the engine gulped the fuel, it was actually more economical cruising at 90mph on the motorway than in the cut and thrust of London traffic - 20 to 30mpg, whereas it could get near to 40mpg out of town. I could only guess that at lower revs the engine was extremely inefficient because Yamaha had concentrated on making the fuel flow work higher up the rev range; for all its apparent mildness at lower revs it was still a 500cc motor that made 80 horses!
My excessive use of the bike in town also did for the clutch plates, they lasted between 7000 and 10,000 miles. I was tempted to do something about the final gearing, to give the bike an easier time in town but couldn’t find anyone who sold sprockets in anything other than the stock ratios, although I didn’t try very hard if the truth be told. The gear change was pretty good even when the chain was knackered or the clutch on its last legs.
Although my finances are very limited at the moment, I do take the RD for an occasional blast out into the country. It’ll cruise at any speed you want up to about 130mph, when power tails off. The chassis doesn’t feel very secure at that kind of speed, the back end hopping about a bit and the front end feeling very vague. The bike is quite heavy going through curves, with lots of wallowing and the odd bit of head shaking when bumps intrude. I’ve never had any lurid speed wobbles so the wraparound square section frame can't be all bad. There’s all kind of kit around to sort out the chassis but my bike is still stock even down to the inadequate rear shock.
Doing 200 to 300 miles in a day is no problem. The only thing that’s afflicted by engine vibes is the fairing which buzzes annoyingly. The light was pretty blinding until it exploded after being hit by a stone kicked up off the tarmac. I couldn’t find a RD500 replacement so had to bodge on a breaker’s special, which has never given the same degree of forward visibility. The seat starts to become a pain after about 100 miles, although the bum stop helps brace my body, whilst the fairing gives a useful amount of protection against the raging gale the bike produces.
I once did 600 miles in a day. My head was ringing from the exhaust wail, I staggered off the bike all bent up, my muscles so tired out I could barely push the RD500 into the garage. I didn’t go near the RD for two days afterwards and never repeated the experience. The Yam’s more obvious purpose in life is to scratch down fast A-roads or good B-roads, which on Metzelers it could handle with aplomb if you ignored the way it walked around a bit on its rather tired suspension. With the power valve working, the thing would hurtle forward with. grin inducing acceleration.
In practice, the smaller RD350 would be more useful for the kind of riding I do these day. Perhaps that’s why the 500 never really caught on, its handling, complexity and performance were never so much more superior to the little twin, that its purchase could be justified, and, anyway, the four stroke 600s offered just as much performance with better longevity and lower costs.
I want two grand for my machine, which no-one seems willing to pay. One jerk offered £700, which nearly got him a mouthful of knuckles. The bike still looks good, apart from the exhaust which is original, whole, but a bit rusty where the black paint has fallen off. Having done a relatively trouble free 32000 miles on the machine, I’ve nothing but praise for its durability. When I do finally find someone to give me some decent money for the RD, !'ll probably end up on a horrible C90 or something equally mundane.
Ernie Howel