D.14/4 Bantam

These photographs show a D.14/4 Bantam engine that was brought in for full engine reconditioning and a complete revision of the existing Wipac electrical system,with the intention of obtaining a high degree of reliability for daily use.

The flywheels were replaced with disc-less D.7 items, which were machined to obtain adequate con-rod clearances on the inner faces. The mainshafts were replaced with the D.14 /4 items, and the crank-seal arbours machined back to be fitted with stainless - steel collars to reinstate the seal running surface,which had become pitted by corrosion. Assembled with a new rod kit, new seals and bearings throughout,and a rebored cylinder and piston, attention then turned to the electrical equipment.

 A split sleeve was machined up to adapt a Lucas RM21 alternator rotor to the D.14/4 left hand mainshaft. A Woodruff key was then turned and milled from E.N.8 steel to fit the altered dimensions presented by the Lucas rotor.
 Small adaptor sleeves were turned up to allow the Lucas encapsulated stator to sit correctly on the smaller diameter Wipac type studs. The engine now has the same electrical output ( 120 Watts ) as a heavyweight British twin or triple, which enabled us to fit an electronic ignition system besides having powerful and effective lighting.  The system used was a Boyer MkIII, with an adaptor plate to carry the pick up stator slightly further out than would have been the case with the original points system. An adaptive rotor was turned and milled from E.N.1A, and the Boyer magnets fitted using 3mm button-head Allen bolts. The amplifier now runs at a fixed advance of 19 degrees BTDC, and although having a wasted spark 180 degrees later, that will not affect the engines running in any way. A single 12V coil will be used, and should be more than adequate,but greater spark intensity would be available if needed.All in all, a pleasant little lightweight engine that has now been developed further and more appropriately, and which will be a pleasure to use in the years to come.


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