There is a turn-on time and a turn off time for the SRC.
For a BT151 this times are 2 and 70 uS.
So within the 63 uS the SCR didn't closed.
No closing SCR, no building up power into the capacitor.

Again, multi spark for this small engines are wast of energie.
We use very small batteries and very small engines.....there is no reason to use it.
The coils must be bigger, the batterie must be bigger and rpm goes down.

BTW, you need atleast 20mJ (normal 50mJ) at 6 bar cilinder pressure to get a spark.
Somewhere into the CDI topics I've calculate it.

http://en.wikipedia.org/wiki/Capacit...harge_ignition