Ignition

Hi Leo,

   I do not know the answer specifically for the 912IS. However it is very common on engines for this to happen it is called "wasted spark". This has no impact unless there is compression of a suitable mixture there will be no burning.

Waste spark ignition is a common practice.  It however occurs on the exhaust stroke not intake.  On the exhaust there is no fuel to burn left therefore it is just to make spark distribution easier.  Check the firing order of the engine and you will see what each cylinder is doing.

Cheers

It’s intake stroke tho in the 2 cylinder

Leo, no it is not.  If it sparked on intake you would have an explosion given there is fuel in the cylinder.  

FIRING ORDER

1-4-2-3

Cheers

Hi Leo....well I had to have a good look at it and technically you are right.  The intake is just start of the cycle when that spark occurs, 4 degrees BTDC or 3 ATDC depending on if it is soft start or the older version.  As such we know there is not enough fuel to ignite it at that point.  

( I had to make some little drawings and review, silly me.) 

Cheers