Just to clarify, it's possible the VW engine has a waste spark during the exhaust cycle, this is not all that uncommon with lawnmower engines. On Mon, Mar 7, 2011 at 4:59 PM, Michael Watterson wrote= : > On 07/03/2011 21:40, Andre Abelian wrote: >> Michael, >> >> I know one thing for sure that the rotor has 4 magnets and 1 turn of rot= or will >> fire 4 cylinder. >> I just do not understand what does "Four stroke is 1 spark every two rev= olution" >> means? >> can you give and example? >> >> thanks >> >> AA > The four strokes > Revolution 1 > INTAKE stroke =A0Piston descends and sucks in air and fuel (inlet valve o= pen) > Compression Stroke,Piston rises (all valves closed) =A0Piston rises and > just before top dead centre, spark is applied > Revolution 2 > Piston descends due to ignition of fuel/air mixture gas pressure > Exhaust stroke (exit valve open), piston rises and pushes out waste > exhaust gases. > > So each cylinder gets a spark once every two revolutions. > With four cylinders, each compresses and gets a spark in turn, so 4 > sparks every 2 revolutions. Cam has 4 bumps for "points" or 4 magnets > and distributor cap on same shaft, four contacts. > * > > * > -- > http://www.piclist.com PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .