CMM RETRO RE­BOOT RD350LC

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Classic Motorcycle Mechanics - - CONTENTS -

Work has started on the IDP Moto/ CMM re­booted rd350lc for to­day’s mo­tor­cy­clist. Ex­cited? We are!

It is hap­pen­ing, it’s re­ally hap­pen­ing: idp moto and CMM’S vi­sion for a new ver­sion of the clas­sic Yamaha rd350lc is on its wheels. To re­cap: we had so many pos­i­tive re­sponses from our retro re­boot of the rd350lc of June 2014, that daryll Young of IDP Moto had a dream, a dream to pro­duce a num­ber of th­ese stunning beasts for the pay­ing public. Chat­ting with daryll it was clear that to be a suc­cess this ma­chine needs to look just like our re­boot, ride like an orig­i­nal – if up­dated rd – and look as if it could be in a 2015 Yamaha brochure. The ‘re­booted’ spec of the LC saw 43mm up­side-down forks, mod­ern r6 swingarm and Brembo monoblock calipers along­side body­work that mim­ics the orig­i­nal and a mo­tor pro­vid­ing a fair bit more oomph over the orig­i­nal’s 47bhp – we’d like around 60-70. Colours had to closely match the orig­i­nal schemes that we fell in love with back in 1980. With the bike mean­ing so much to so many of us, the job is go­ing to be a hard one to get right. But we love a chal­lenge. so what’s hap­pened so far? Well, our own Niall Mackenzie de­liv­ered his fully re­stored rd350lc to IDP

to begin the first, vi­tal task. Daryll says: “The first thing was to get all the nec­es­sary mea­sure­ments from the orig­i­nal to lay over what we wanted to do. Ev­ery mi­nor de­tail, has been logged from ba­sic ge­om­e­try through to width of the bars, height, po­si­tion­ing – ev­ery­thing. “This is be­cause it’s not just for en­gi­neer­ing pur­poses but be­cause we need to get the feel of the orig­i­nal bike right. It can’t be too far away from the orig­i­nal.” With this in mind there’s al­ready a styling is­sue. “Wheels and run­ning gear have thrown up some prob­lems,” says Daryll. “The orig­i­nal Italic wheels have been scanned as has a cur­rent R6 rear wheel that we’re bas­ing the fit­ment on. First is­sue is of style: look at the pic­tures of the bike on our bench with R6 swingarm and forks in place and you may not see it, but with the R6 wheel in, it just looks ‘too wide’ for an RD350LC. “Our orig­i­nal plan of 180-55 17in Italic wheels has been put on hold while we in­ves­ti­gate other op­tions. We feel per­haps the 6in rim should in­stead go to a 4.5in rim – and a 160-60-17 rear tyre. Con­ti­nen­tal has come on board to help with tyres so we are work­ing with them on the choice: the de­sign it­self of the wheel looks like the orig­i­nal, we’ve just frozen the ac­tual man­u­fac­ture while we fi­nalise wheel di­men­sions. “Re­mem­ber, this has to ride right not just look right, so it could well be that our test mule will see Niall testing var­i­ous per­mu­ta­tions be­fore we get it right. The other is­sue is the R6 swingarm is clearly longer than the orig­i­nal LC’S so if it’s (say) 40mm longer we don’t want it to han­dle like a bus. It’s still got to want to wheelie on the throt­tle like the orig­i­nal one did.” Other look/fit prob­lems also need to be re­solved. The tank will be a hy­brid of the orig­i­nal and a more mod­ern/cur­rent R6. “Cur­rently we are hav­ing the top of a 2015 YZF-R6 tank grafted onto an orig­i­nal. So you’ve got the shape of the orig­i­nal RD with the new-style filler cap and slope-down at the front. Even things like the seat are caus­ing headaches. “We want to ei­ther find some­thing iden­ti­cal to the seat cov­er­ing used at the time with RDS or aim for some­thing like that used by Yamaha to­day. We find that the af­ter­mar­ket sup­pli­ers’ seat cov­er­ing is dif­fer­ent to both and it looks odd.”

En­gine-wise Daryll says IDP will have two mo­tors for testing: one stan­dard sim­ply to slot into a chas­sis for sus­pen­sion and ge­om­e­try tests, and a mildly tuned ver­sion which will give some idea of what the fin­ished bike will have. Again it’s all bal­ance, as James Whitham once said, the beauty of the LC was that it had just enough power, not too much. Watch­ing our project with in­ter­est is Bob Trigg. Bob spent many years in the Bri­tish bike in­dus­try, help­ing de­velop of many Nor­ton Vil­liers Tri­umph prod­ucts, such as the Nor­ton Commando. He got in­volved with the orig­i­nal RD250/350LC projects along with Paul But­ler, later chief ex­ec­u­tive of IRTA in grand prix rac­ing. While at Yamaha Europe, Trigg worked with stylist Mick Ofield and But­ler in prod­uct devel­op­ment. Ofield sent de­sign ideas for the new 250/350 such as the line of the fuel tank, and they were used by the de­sign team back in Ja­pan. So what worked with the orig­i­nal that could help our ‘new’ RD350LC build? Bob says: “Suc­cess of the orig­i­nal de­sign was that it was a col­lec­tion of ideas that in­di­vid­u­ally weren’t sig­nif­i­cant but to­gether worked well. The bike could be all things to all rid­ers: a prac­ti­cal solo ma­chine and also good with a pas­sen­ger, and it could blow off al­most any­thing on the road. Also you could re­move fea­tures of the styling and not lose much in the looks.” Testing of our new RD350LC looks to be get­ting un­der way at Sil­ver­stone in May: “Once Niall has test rid­den and ap­proved the de­sign of the pro­to­type we will begin to pro­duce the first 2015 RD350LC, and would hope to be able to un­veil the fin­ished ma­chine here at Sil­ver­stone cir­cuit early to mid-sum­mer,” says Daryll. “So far, we’ve done so much on this project and we still clearly have a very long way to go. The in­ter­est shown by read­ers in this project has been un­be­liev­able.”

A brew, a tape-mea­sure, steel rule and an orig­i­nal bike. Time to mea­sure!

Craig at IDP Moto got the short straw and was roped in to do the mea­sur­ing. Test mule frame ready to begin as­sem­bly.

Even the bare bones of the chas­sis looks saucy. Stan­dard mo­tor will be in the test mule.

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