Fac­tory Spe­cial

Honda 360

Classic Trial - - NEWS - Ar­ti­cle: Jean Cail­lou and John Hulme • Pic­tures: JC and Eric Kitchen

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.

Light­weight ma­te­rial

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

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.

Gera­nium red

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.

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