Restoring a works trials machine is not very much more difficult than working on a production bike, the problem is in finding one! And when it comes to an ex-Rob Shepherd 1979 Honda RTL 360 it's like touching the Holy Grail of the greatest era of trials history. Come a little closer and look inside, you lucky readers, as we unravel the big red puzzle.
The Honda RTL 360's career spans over seven years without much change, and the happy few who received two per season from Japan had a tendency to keep everything they could to gather a good little stock of spares year after year. In theory, everything was supposed to be destroyed at the end of each season to avoid paying huge import taxes, the machines and parts being sent to Europe tax-free only if they stayed there no longer than one year; well this was the theory, but the Japanese didn't want to pay for their return!
Detective work and negotiations
Who could blame job-loving mechanics to be reluctant to send all these beautiful parts made of precious metal to the crusher? It is how this Honda engine was saved by a former Honda Britain employee and later sold to yours truly.
The frame was traced in Belgium where several ex-Shepherd machines were sent in 1981, when he put an end to his brilliant career, to be used by Japanese test rider Kiyo Hattori. The wheels with their magnesium hubs were found in a shed by Sammy Miller, Shep's former team manager.
It may sound easy summed up like this, but the quest actually took about 15 years in total. It also meant numerous encounters, trips abroad, hours of detective work and negotiations without any consideration for overall cost, all rare things being expensive as you will know. At least the expense was spread over many years, which makes it sound better. The goal however, was not to put this precious motorcycle in a safe; it had to be restored for good use thus leading to possible deviations from authenticity but hopefully not too many.
Apart from the modern Michelin tyres, which had to be fitted to replace the original hard-as-wood MT43 Pirellis, there will be only one deviation, the tank and seat unit. This beautiful featherweight fibreglass piece is as thin as cigarette paper, and a mould was made to make an accurate copy just a little thicker, for obvious reasons. We had to forget the extra weight, which was not too much when we replicated it. At least it might not explode on its first encounter with a sharp rock, just as happened to Rob himself at the 1979 Scott Trial, who eventually lost out on victory due to a hefty loss of fuel through the gaping hole which was the size of his fist!
Aluminium inserts for the fuel cap and tap had to be machined. The cap would come as an off-the-shelf part from the Honda TL125 and the fuel tap itself from an unidentified Honda moped model from the '70s. It took several years to find, and eventually, one was located at an autojumble in Belgium. Of course, when parts are simply missing you must have them reproduced.
Having previously restored Eddy Lejeune's 1982 world championship-winning RTL 360, it helped a great deal since they are quite similar. One of its rear shock absorbers was sent to Rockshocks in England with spare springs, rings and cups. Rockshocks owner Gary Fleckney was able to make accurate copies, machining bodies from billet. Yes, it took almost seven months, but it was well worth the wait since they work even better than the original units. The air filter had to be reproduced as well, as there is no such hand-made item in the Honda catalogue. Other than that, it has no electronic ignition, and the conventional points almost never need adjustment. The coil, with its piggy-back condenser, can be found on several Honda period models. Black Renthal handlebars bars were even found which was not so easy, thank you to Oliver Barjon for these, so you can have the true Rob Shepherd ‘feel' when riding.
The engine is known to be bulletproof; however, the con-rod tended to wear out on the gudgeon pin side and is too thin to insert a plain bearing. A thicker pin had to be found and was fitted after boring out its housings in the piston. With this, the engine became smooth and silent again. The bottom end needed no such work at all.
Strangely, the rockers were missing from the engine. A small batch was made at a high cost, but they proved unsatisfactory. Fortunately, a ‘NOS’ pair was eventually traced in Belgium – thank you Patrick
Pissis – and saved from an HRC dustbin. Their axles were also missing, but they could be replaced with standard Honda XL250 parts that just needed to be shortened. The clutch plates are identical to Honda CR250 motocross models. The crankcase and its covers are made of magnesium and are carefully varnished inside and painted outside, which protected them well from corrosion.
The varnish remained as it was but the outside was gently blasted with peach-stone powder and then protected with a layer of selenium anhydride diluted in water. It is a molecular treatment that turns the light metal into a funny dark-pink colour. It was then coated with Restom's special engine paint. Take it to the kitchen oven for about an hour
while your mother is away, and you're done!
Reassembly is no big deal as long as you've timed a four-stroke single before; timing marks can help, and a new head gasket has been manufactured replicating the old one. Tuning is easy as we just copy what has been done on several other RTL306s and 360s which have been restored over the years with fellow RTLR Club members, about eight altogether.
The rolling chassis is a conventional steel frame which has been lightly sanded, revealing its serial number on the headstock, RTL360F for Frame — 0379 confirming it was made in March 1979. A thin layer of sizing is sprayed on and
then three coats of PPG paint of the correct orangered. There is a Citroën colour-coded Geranium Red, which is perfect!
Thanks to a small stock of spares gathered over the years to restore other factory Hondas almost all the compulsory titanium bolts and nuts have been found. If not, you can expect to spend another £2,000 to have them made as they are all specific.
The swinging arm pivots on plastic bushes that can still be found at your Honda dealer, they are a TLR reference as well as their dust covers. As the chain tensioner pad is no longer available, be prepared to pay around $50 on eBay. The front forks are formed on a milling machine from billet but are otherwise quite conventional — they received an air valve two years later.
Their 35mm oil seals can be easily found as they are the same as the Honda CB750. New spokes from a Honda TL125 can replace corroded ones if needed. The DID wheel rims are also the same as production ones but with holes on the sides for the tyre-retaining self-tapping screws. Modern security bolts are recommended though, at least on the rear wheel.
A brand new throttle cable from the HondaTL250 from Venhill was a sensible improvement with the old one being completely stuck. After the engine rebuild and some fuel in the cylinders — not too much — and with two ‘prods’ on the kickstart lever, the first one to charge the condenser, and it burst into life. Now let's go for the steepest, slippery climbs we can find to hear that distinctive Honda exhaust note, which now sounds maybe just a little beefier!
Some history of the machines
I am working on a book to tell the Honda trials history, but here we can tell you a brief history of the frame.
In 1974, Honda decided to enter the sport of motorcycle trials. The little TL125 four-stroke had been launched a year earlier, and the TL250 model was about to appear when they hired Sammy Miller of Ariel and Bultaco fame to develop a real winner and head a competition team of riders in England while Bob Nickelsen, in California, led an American equivalent.
In 1975, after a couple of prototypes were built by Miller housing modified TL250 engines into his Hi-Boy frames came the RTL300 – actually capacity
a 305cc — for Nick Jefferies and Marland Whaley to ride. Whaley rode his to victory in the American championship.
As early as 1976 an all-new prototype was unveiled, also named the RTL300, but in reality, it was a 306cc and had lost two of its four valves. The engine was made of magnesium, apart from the aluminium cylinder head, and, above all, the stroke was only 58mm instead of 74mm with a much bigger piston, quickly bringing the nickname 'short-stroke' as opposed to the previous 'longstroke'. With the crankshaft being much lighter the little jewel was graced with several other magnesium parts and titanium bolts and nuts and tipped the scale at only 85kg – 187lbs – which is less than any other two-stroke competitor! However, it lacked smoothness and also power at a time when the world championship sections were getting bigger and bigger and, you have guessed it, needing more power at all times.
So for 1978, after parting with Miller, Honda gave Rob Shepherd who was the newly-crowned British champion in 1977 aboard the 'old' 305 long-stroke an evolution of the 306 stroked to 68mm to give it a capacity size 359 cc, and this is where RTL360 model name came from.
Receiving the new beast only days before the demanding 1978 SSDT Rob nevertheless took it to sixth place. Then the engine started showing problems due to its chrome-plated liner leading to engine seizure when it was over-heating. The solution was to fit a more conventional steel liner. With its heavier crank the machine now weighed about 10kg more – over 200lbs in total – but it was also the most powerful one around; nothing could stop this engine, but sometimes it proved difficult to ride! It maybe explains why, despite public demand, they never dared make a replica of this machine for the average rider.
After finishing fourth in the 1979 SSDT, and then third in 1980, he rounded off the season in fifth in the World Trials Championship.
After leaving Honda the young Belgian Eddy Lejeune took the mighty RTL360 to the highest level, winning three world championships in a row, 1982, '83 and ‘84. Its engine crankcases were now made of stronger aluminium with a steel oil cooler, and the frame was reinforced in places, bringing the overall dry weight to over 97kg/214lbs.
In 1985, Eddy rode a radical monoshock evolution of the 360 to second place in the world championship. He, and Great Britain’s Steve Saunders, were then given RTL270s to fight for a podium place behind the new World Champion Thierry Michaud. These smaller-capacity machines were to be dropped after only two seasons. It would be many years until four-stroke trials machines became popular again with Spain’s Toni Bou leading the way with Honda in 2007 as a new world champion.
The engine is very compact, despite its overhead camshaft. Note the high position of the gearchange lever, typical of this works Honda.
A truly classic line... The exhaust silencer, made of thin steel, takes up every space available to produce a very quiet note.
The engine that everyone wanted.
This fully magnesium aircooled engine is unique in Honda engineering with its one-piece top crankcase and cylinder! It's mechanically rather simple, a clue to reliability.
The last twin-shock win in the FIM World Trials Championship was with Lejuene and Honda in 1984.
The long kickstart lever was required to bring the four-stroke engine to life.
The engine is in place — a shoehorn was very useful!
A thin layer of undercoat dries under the summer sun; three layers of Citroen Geranium red will be sprayed over to bring the frame back to life.
A factory engine needs as many titanium bolts as possible!
The ex-Shepherd 1979 RTL360 with its stablemate Eddy Lejeune's 1982 world championship-winning model.
Rob Shepherd (left) with Jean Caillou.
The crankcases and their covers received a coat of special Restom paint before spending an hour in the oven.
The alloy cylinder head with its big valves and the old head gasket. The power reaches 20HP.
The oil pump is driven by the kickstart pinion as often seen on Honda engines.
Rob himself has tested his old steed himself but he confessed to liking Eddy's machine better…
All these years on the machine attracts interest wherever it goes.
The original 1979 Scott Trial tank and seat unit has been carefully repaired and signed by Rob, but remains too fragile to be used.
Jean Caillou is a four-stroke man in all areas of motorcycles.
Rob Shepherd riding the featured machine in 1979 when it looked almost new, just as it does once again.