Main Motorcycle: Bonneville T100 SMQ SE
Join Date: Dec 2014
Location: Vancouver, Canada
Other Motorcycle: 1974 Norton Commando 850
I'm new to vintage bikes ('74 Commando since Jan. '18)...but I've fitted an electronic Ignition similar to Boyer (Vape Wassell). Before setting it, I needed to check the mechanical timing....crank position mark plate on engine cover for accuracy against the actual piston position. The Boyer & Wassell E.I.'s need 28 degrees BTDC at full advanced RPM (about 5000 rpm on the Commando). To check that, I need to know what mark on the crank gauge to use as 28 Deg BTDC. Marks on my cover's gauge were out 1.5 degrees (I determined this via a degree wheel on crank and a piston stop made out of a hollowed out spark plug with a section of old spoke epoxied through it. So, I set the crank mark to align to 28 BTDC, then lined up the line & marks on the E.I. stator & rotor before nipping up the E.I. rotor to the cam shaft. This gets the EI in the ball park of 28 degrees BTDC (at full advance) good enough for starting/running....then a timing light gun is used to fine tune that rotor/stator alignment while watching the crank mark vs the cover mark for 28 degrees.
Note it is possible to set the timing to 180 degree off quite easily...by using the incorrect stator/rotor marks for your engine or camshaft rotation direction (check the Boyer docs). Also easy to think your at TDC when actually at BDC if you do not use a piston stop or something else to determine piston is up with its valves fully closed). Also, check the ignition system wiring is as per the Boyer docs for your engine (positive or negative ground, 2x6v coils or 12v coils etc.
2013 T100 Steve McQueen; +NH Togas; -SAI; -O2; +Breathe; +TTP#3; +Avon RoadRiders; +Iron&Resin Sidebag; +Kisan Auto-Off Indicators & BrakeLight Flasher; +MatchlessClueless LED Brake & Indicators; +LED 3000 Lumens Headlamp; +DeCosse Keyless system
Last edited by Tornado99; 09-04-2018 at 05:58 PM.