Was in NZ for work for a few days this week and spent some time with my buddy Brent (aka 'Captain' on the CB1100F site). We discussed at length about ignition etc. and just wanted to post some of that chat here, more to get people thinking about possibilities and alternatives.
In any engine, EVERYTHING happens (or is supposed to happen) in relation to the position of the crankshaft itself as it rotates through the combustion cycle. This includes camshaft rotation and position, valve opening and closing and when the spark occurs at the plug. The more precisely you can make these events happen in relation to crankshaft position, the better the engine will run and the more consistent power it will produce.
On a CBX engine, unfortunately, the spark auto advance which triggers the spark event as it passes the pulser unit, is connected not directly to the crankshaft, but to the jack shaft (or primary shaft by another name). And the jack shaft is connected to the crankshaft by the very flexible toothed primary chain, which is subject to wear and tear, esp. as the mileage stacks up and the engine is constantly having the throttle opened and closed, making the primary chain come under load (tighten up), then off load (release) as the throttle is opened and closed.
As the primary chain wears over the life of the engine, and probably the hydraulic pressure of the primary chain tensioner also reduces, this slack in the chain MUST allow the jack shaft to "move around" or 'rotate' slightly in direct relation to the crankshaft itself - ie; it is NOT fixed. And because the jack shaft position (in relation to the crankshaft) changes, then so must the ignition timing events also move around in relation to the crankshaft.
Clearly the very best place from which to trigger the ignition events would be directly off the crankshaft itself in some way. Have not yet done any research on this, but am thinking the LH end of the crankshaft may be a possibility. Given the increasingly small triggering mechanisms available today, perhaps a nice CNC milled spacer plate between the LH crank end cover and the crankcase may provide sufficient space to install one. Of course how to precisely set up the trigger on the crankshaft is another issue to be solved, but just thought I would put it out there for minds far greater and skilled than mine to mull over and also share their thoughts.
Cheers..Tony
