Entries by adrian

dyno roller – in the groove

ow that the shaft has been shrunk into the roller, the assembly goes into a CNC lathe to take a lick off the O.D. and to machine cross grooves using the live tooling of the machine. Not many dyno rollers have this feature (usually heavy knurl instead) and I’m exceedingly lucky to have access to […]

Big lump ‘o’ steel

he dyno roller starts off with a raw hunk of K1045 steel, 460mm in diameter and weighing 400kg. Some people turn down each end to form stub axles, but in my case, the shaft is quite long so this is not feasible.  Instead, the shaft will be made separately and shrunk into the lump.   […]

The dyno roller

The lump has a polar moment of inertia of 10.07 m^2 kg. So your average airhead should produce a run of around 10 seconds in 4th gear. If  successful at getting around 90hp at the back wheel of the salt racer then runs will need to be done in top gear. In which case, that […]

dyno – exploded view

ere’s an exploded view of the dyno design. The main wheel has been sized to suit the types of bikes that I will be testing: bikes from the 70’s and 80’s, mainly airheads. The red wheels are removeable and  can be installed to cater for bikes with more horsepower. A disk brake is incorporated to […]

luftkopf No. 1 – BMW Cafe Racer

Cafe’d 1981 R100RS: Custom werk by skrunkwerks: Carbon fibre filter filler and rear wheel hugger  :  Rear tail piece  :  Custom bracketry to lower S-fairing  :  Rearsets  :  Clip-ons  :  Triple clamp  :  Mufflers  :  Paint job  :  Dual plugging  : Head porting Other bits: 336 BMW Sports Cam :  38mm Dellorto carbs  :  Koni […]

measuring compression ratio – method 1

ncreasing the compression ratio of luftkopf #1 is long overdue. Aside from being one of the easiest ways of adding horses, the 336 cam wants it badly. The valve pockets in the piston domes have been deepened to accommodate the higher lift of the cam and I have often wondered what difference this would make […]

dual plugging – modifying the bean can

The engine speed at which maximum advance is reached is dictated by the weight of the conterweights and the stiffness of the small retaining springs. Being a 1981 model, my bike was fitted with the earliest of hall effect beancans. These seem to have heavier counterweights. As a consquence, the springs are slightly stiffer than […]

dual plugging – timing

  here are two main camps for the spark timing of a dual plugged airhead engine. Both seem in rough agreement that timing should be retarded to about 28 degrees at maximum advance compared to the stock BMW timing specification of 32 degrees. This retardation of the spark (compared to the stock setting) is necessary […]

salt racer

e’re off to the big white dyno at Lake Gairdner for speedweek 2015. The image is of Brett Destoop, fastest man in Australia…… and the world in the APSF-1000 category. 232 MPH (371 km/h) Lake Gairdner. Thanks to Simon Davidson  for allowing me to feature his image. You can see more of  Simon’s work at […]