MATE Building Instructions - Page 2

 

BUSHING (2-1)

  1. Centre phosphor-bronze stock and extend 37mm from chuck jaws. Finish turn to Ø12.7mm and face end.
  2. Centre-drill and drill Ø8mm x 35mm deep.
  3. Break edges and part-off at 30mm from faced end.

VENTURI (2-2)

  1. Centre (Ø19mm) aluminium stock and extend 27mm, finish turn to Ø9.5mm and face end. Bell-mouth with a centre-drill.
  2. Drill Ø3mm x 27mm deep, then drill Ø5mm. Finish venturi bore to size with a Ø5.5mm drill, fed slowly at high spindle speed. Break edges and part off at 22mm from the faced end.
  3. Centre other end in chuck and extend 5mm. Finish turn to Ø7.5mm x 4mm.
  4. Transfer the venturi to the milling machine vyce, clamping it firmly at the ends. Mill the first .75mm deep slot with a 1/4" slot drill centred 10mm from the bell-mouthed end.
  5. Turn the venturi through 180 ° and clamp again, resting on a narrow piece of parallel packing under the first slot to ensure alignment. Mill the second slot.
  6. Move the venturi sideways to centre its axis under the machine spindle. Centre-drill and drill the Ø3mm through hole for the spraybar.

BACKPLATE (2-3)

  1. Centre the (Ø31.75mm) aluminium stock in the chuck and extend 20mm. Finish turn to Ø27mm x 14mm long.
  2. Face end and bore recess to Ø20mm x 9.5mm deep. At 2.5mm from faced end, plunge cut to Ø23mm with the 1.6mm wide parting tool.
  3. Turn down to major thread Ø24.5mm and chamfer a 45 x 1 mm deep vee with your chamfer tool, centred at 11 mm from the faced end. This will be our thread run-out.
  4. Proceed to cut a 1mm pitch thread x .615mm deep, entering at the 1.6mm wide recess. The thread depth specified assumes a minimal tool nose radius and you may have to adjust yours accordingly.
  5. Part-off the backplate at 11mm from the faced end. In the unlikely event you anticipate some difficulty obtaining a smooth part, allow a further .5mm over length. Reverse the backplate, mounting it on a mandrel. Face off the surplus.
  6. Place the backplate, its threads protected by paper, in a chuck, which is in turn mounted vertically on the milling machine table. Cut the 2.5mm wide x 1mm deep tightening slots with a slot drill. De-burr with a needle file. A suitable steel blade, not a pair of long-nosed pliers, will be used across these slots to tighten the backplate against the crankcase.

 

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