HIT SIN­GLES

Q. How does one pis­ton make a claimed 70bhp? A. 21 years of work – and a fac­tory that loves sin­gles

Motorcycle News (UK) - - GARAGE - Se­bas­tian Fais­tauer

Se­bas­tian is head of engi­neer­ing for KTM’S LC4 project, which de­vel­oped the two road ver­sions of the world’s most pow­er­ful pro­duc­tion sin­gle: the £7000 Duke 690 and the £9000 690R “The Duke orig­i­nated in 1994, and it has be­come a cult bike. We have sold more than 68,000 LC4S, most of them Dukes of one sort or an­other. To­day’s bikes are our fifth gen­er­a­tion, and the sec­ond ma­jor up­date on the 690 en­gine in­tro­duced in 2008. We now have 300 R&D en­gi­neers in our fac­tory at Mat­tighofen. It’s the only way a bike this so­phis­ti­cated can come to mar­ket. Of 33,000 hours spent de­vel­op­ing the new model, 20,000 fo­cused on the en­gine. Half the com­po­nents are new, in­clud­ing the crank as­sem­bly, pis­ton, cylin­der head and bal­ancer sys­tem. The re­sult is 7% more power and 6% more torque (73bhp and 54.6ftlb), and an in­crease in peak revs from 8250 to 9000rpm.”

Mo­tor­cy­cle Ac­ci­dent So­lic­i­tors The rock­ers use spe­cial steel The Duke’s pis­ton is heav­ily milled to save vi­tal weight Clever res­onator helps the en­gine run at part throt­tle

Bal­ancer shaft bear­ing hous­ing Sec­ondary bal­ancer (to can­cel ef­fect of pri­mary bal­ancer and crank) Twin side-en­try stick coils and plugs run­ning dif­fer­ent ig­ni­tion maps (shared with the old model) Sin­gle cam. Outer lobes work the in­let valves via fin­ger fol­low­ers. In­ner lobe works the ex­haust valves via a forked rocker

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