6 Engine Assy 

Drawing/Parts List  600 Engine Assembly is somewhat ambiguous; a number of parts appear twice, with different part numbers, e.g. 607 Crank Shaft and 663 Crank Shaft. In these cases, the part number that showed up on the parts list as well as on the  drawing, was chosen. 

It was noticed that (the end of) 607-663 Crank Shaft was very soft and great care has to be taken not to damage it while dismantling the engine. It is recommended to make a stout brass cup that neatly fits over the end of the crankshaft, to protect the shaft end while applying a few blows with a hammer. 

The  Engine Brackets, LH and RH and the Bolts for attaching the engine to the frame are not listed in the Part Lists.
Model A with Frame # 2217 and Engine # 2213 did not have the engine brackets and was fitted like drawn in Motoring on two wheels, page  32, so it can be concluded that these brackets have been fitted for a different purpose, the reason of which is unknown to me. 

Photograph and dimensions wanted of 654-Clip, HT. Wire 

The inlet port is positioned at the rear side of the cylinder, the exhaust port at the left hand side and the scavenging port at the right hand side.At the front side, the cylinder wall is uninterrupted.

The piston skirt has holes in its circumference, mainly around the scavenging port.
The holes do not have a function with respect to the gas flow and the reason for having these holes is unknown to me.

Is there anyone who knows what the holes in the piston skirt are for? 

Timing diagram:

The timing diagram is based upon measurements on the good running engine No. 2173.

The values in red between brackets are measured on spare engine No. 1108, with the ignition set exactly on the arrow.

 All values are converted into mm. 

Stroke:                                                                      2.75”               70 mm

Bore:                                                                         2.5”                 64 mm

Capacity                                                                   13.5 cu.in      221 cc

Compression ratio                                                  2,76 : 1

Effective height piston:                                         3 1/32”           77 mm

Length connecting rod:                                        5 ¾”    146 mm

Exhaust port opens and closes                           71° (74°) before / after BDC

Scavenging port opens and closes                    61° (57°) before / after BDC

Inlet (carburettor) port opens and closes           49° (51°) before / after TDC

Ignition (contact breakers to open) 4 mm before TDC = 25° (3,5 mm = 23°)

Rule of thumb for these type of engines                       10% of stroke=7 mm bef’re TDC=33 °

Contact breakers close (10,5 mm) after TDC = (43°)

 Recommended sparking plugs (Source, Martin Philp): Champion D16 or NGK A6

Ben Geutskens                                                                                          September  2014