Mick Payne
In the beginning, how did the first event come about? Perhaps a meeting of two committed riders each out to prove that their machine, or the rider, were the better?
Sadly for them, the 45rpm single and ‘record racing’ was still decades away so the dusty pre-First World War roads had to suffice. This morphed into organised hill climbs and road trials for both solos and sidecars with three wheelers such as Morgan competing too. These early sporting sidecars were the very machines the owner would have ridden to work on the following Monday. Development remained static until circuit racing evolved which meant new venues such as Brooklands; this was at a time when roads were limited to 20mph. This speed limit didn’t prevent events such as the Motor Cycling Club’s (MCC) Edinburgh Trial being run from 1906 when Muriel Hind completed the 391 miles in less than 24 hours, driving a Singer Tricar. This event still has a sidecar presence.
The sidecar has a place in just about every form of motorsport, from sprinting to speedway, as well as the more refined observed trials.
It’s probably the Isle of Man TT that provides some of the most exciting sidecar sport, although here development hasn’t always been linear. The first sidecar TT of 1923 was won by Freddie Dixon and T W Denney with a special banking Douglas outfit equipped with disc brakes. Sadly this proved a bit of a development dead end.
The average speed of this outfit was 53.15mph and a few years later the class was dropped owing to lack of entries and was not reinstated until 1954 (as mentioned in last month’s issue). Progress was rapid with the development of chassis and streamlining and the general lowering of outfits brought about by the ‘kneeler’ riding position and 16in tyres. The sidecar changed from front entry, where the passenger did their stuff in front of the wheel to the, now conventional, rear entry with increased streamlining. The record speed around the TT is now 119.25 mph.
Off-road sport has changed too. From the early days of road trials to more specialised observed trials the outfit has become more focused on the job in hand. A rider in the 1950s would still recognise the modern version but be amazed by its skeletal appearance. The almost standard Royal Enfield would still have been rigid rear end and the sidecar probably a Watsonian International, a replica of which is still built by the company today. Fortunately most of these disciplines are kept alive by clubs and hopefully when the current crisis and its restrictions are lifted will restart. So, when they are, try to spectate, help out or even have a go. The Historic Racing sidecar classes are particularly hard fought and, whatever your interest, the MCC long distance trials with their diverse array of vehicles are very entertaining.
Here’s to normality, if it’s still possible!
Honda had arguably spread itself too thin and, as a result, bike development suffered. It was a given that the company's response to the XT500 would be both considered and typically Honda-esque in nature. With its reputation for making stunningly effective yet viceless two wheelers, the XL500 was set to be a technical tour de force.
First up, the motor ran a pent roof combustion chamber for greater fuel efficiency and more power. This was facilitated by a four valve head instead of just a pair of valves as used in the XT.
To maximise on the new engine’s top end, Honda opted for bore 2mm larger than the Yamaha which, in turn, reduced the piston’s stroke by 4mm. These two vital statistics combined to ensure the XL’s piston speed was significantly lower and thus reduced the vibrations associated with big singles, but this was only part of Honda’s master plan for clawing back sales from the upstarts at Iwata.
Next up were a pair of contra-rotating balance shafts which, to a large degree, negated the worst of the motor’s vibrations.
The all-new Honda hit the showrooms in 1979 and was well received by those who wanted a large capacity four stroke single that wasn’t a Yamaha. The bike was definitely more refined than the XT, which was either a good or a bad thing depending on your view point. Some argued that here was the ideal modern big single, while others countered that the bike lacked soul or character – once again a Honda was accused of being bland despite there being no obvious issues.
Period reports tell that the bike was easy to start and ride, the seat was comfortable and fuel consumption figures were favourable at 65mpg on freeways and a fairly creditable 50mpg when ridden hard off road.
On paper, so far so good, but there were also some irritating foibles to the bike. One big issue spotted early on was the way the handling seemed reluctant to turn in to corners. Honda had opted for a highly unusual and ultimately controversial
23 inch front wheel, which effectively noticeably slowed the steering down. The reason for the odd tyre size was logical if not especially sensible. Someone back in Japan had postulated that if you increased the diameter of the front tyre, the bike’s ability to climb over logs, boulders, ruts and the like would be significantly greater and this was immutably correct. Unfortunately the increase in diameter also disproportionately increased the gyroscopic effects and thus, perversely, rendered the bike significantly more stable in a straight line and noticeably more reluctant to turn. There was also the added unseen complication that no one other than the OEM supplier was able to supply tyres.
Just as Yamaha had stripped back the XT500 to deliver the TT500, so Honda did the same with the XL500 to produce the endure-friendly XR500.
The XR came in at the same weight as the TT500 despite the retained balancers set up which undoubtedly made for reduced rider fatigue. That the XR500 was genuinely intended for the dirt was never in question, as evidenced by the massive alloy sump guard, stripped back gauges and super long seat. Unfortunately, when used in anger the XR had less than ideal ‘on the dirt’ manners. Backlash with the gearbox caused jerkiness and this was exacerbated at low engine speeds when throttling off to sometimes deliver a momentarily locked-up rear wheel. The general consensus was that, although acceptable, the XR500 offered nothing over and above the older XT and often and occasionally was found lacking.
The XL500 ran from 1979 to 82 with the XR only managing 79-80. A revised XL500R, with a monoshock rear along with minor revisions, carried on 82-84 with an XR derivate from 81-83. Honda subsequently tweaked and twiddled to produce a 600cc version but the firm’s big bore dirt bikes consistently lived in the shadow of the equivalent Yamahas.
Perhaps one the greatest issues was the long term reliability of the Honda’s top end. Following protocol, the XL/XR top ends all ran the cam directly inside the alloy head with no additional bearing surfaces. It was a viable engineering approach, but only if the oil and filter were regularly changed. Also crucial to the longevity of the cam’s housings was the use of the correct grade of motorcycle specific oil. If all or any of these vital criteria was overlooked the cam would simply eat its way into the housings it sat in, resulting in a cylinder that was scrap without a lot of TLC and engineering knowhow. By comparison, the XT/TT used a cam arrangement that relied on ball races that proved to be almost bombproof.
As an interesting footnote to the XL500, its motor was latterly in great demand when some smart fella found it would fit into the frame of a Honda CB250RS single with precious little work.
The end result was arguably one of the best Q bikes ever to be built in a garden shed…providing of course that its cams were in good order!