There was/is a manual advance/retard available for both the Lucas K1F & K2F magnetos, as soon as you hit the "sweet spot" for the engine you are testing your ing timing on cut the engine, leaving the A/R lever alone, then you can set up a large diameter timing disc , the bigger the better, and take your reading from there. Once set up , then you know you are in the zone.What is the theory behind advancing timing for low compression? 32 degrees was the stock advance for the low compression pistons and magneto when the bike was new. While the twin engine was designed to run on really low octane "pool" petrol, by the 1960's in the US we had easily available high octane fuel.