Since 1990 after having my main bearing housings rebored by Herve' Hamond, on his big mill plus a complete overhaul with bloody heavy Alfa Romeo low expansion pistons 9:1 ratio, lead-free seats, Honda auxiliary oil pump, exhaust lift mechanism refitted so twin plugs could be used. 12 V Bosch dynamo cut down with eventually smaller sprocket after inclining the dynamo about 10 degrees. After it was done it still returned about 50 to 55 MPG and I still called the stops when travelling with Herve' Le Manach'e (002) as he had a "D"Rap with 18 Ltr tank when I went twin plug heads he called the stops and I was always doing 70 plus MPG, Bill Easter in 95 NZ we were doing about 200 miles a day both two up and camping gear I would fill up once a day and John Heugel would be decanting a couple of Ltrs every so often from his large tank BMW, most I ever did was 245 in France solo to bone dry and all vapour used up too.
Ignition is around 24 to 25 degrees with the very economical Grosset trigger unit and often wonder if additional plugs would reduce the ignition even further, as the closer to TDC the less negative forces applied. If one plug can reduce it by 10 degrees then add either side of the valves (four !) of say 8mm diameter! how much more could it be retarded? Is the headstrong enough for additional holes or thick enough?
bananaman.
