I think the 66cc had a 40mm stroke with an 89mm conrod, as where the 48cc has a 38mm stroke with a 85mm conrod. The piston diameters seem correct, but you might want to add these: http://www.spookytoothcycles.com/images/engines/engine-ID.jpgBore x Stroke:
48cc: 40mm x 38mm
66cc: 47mm x 38mm
N.B. Capacity = pi * (Bore/2)² * Stroke. e.g. pi * (4.7/2)² * 3.8 = 65.9cc.
(Calculate in cm.)
That's an easy question to answer: cut a half inch wide strip from the top of a cereal box, approximately 3 inches long. With the magnet is in the horizontal position, slide the cardboard strip around the magnet and along the upper and lower arms of the magneto coil.specs what is the air gap between the mag loop and magnet