Another contributing factor is if you don't get full voltage to the coil with the electronic ignitions it can cause pre ignition so if your battery is not up or you have some bad connections it does more than just slow down the starter. Here are some trouble shooting tips.
Premature Ignition Firing
Either you have the ignition timing to far advanced or a common problem causing this is the supply to the
ignition system. This can be caused by a weak battery or poor supply lines (wiring) to the ignition. The power
for the ignition system is supplied by the battery and the wiring goes as follows: Battery > Starter + > Circuit
Breaker > Ignition Switch > Kill Switch > Ignition Coil > Ignition Module. How many connections are there, and
when was the last time you checked them. What happens is at some point along the supply line to the ignition
there is a high resistance connection causing a voltage drop.
If you have a drop of 3 volts to the ignition and the starter pulls the battery voltage down to 10 volts at start up
the ignition see 7 volts. If the ignition has a dropout voltage of 8 volts (Spyke Ignitions have a dropout of less
than 5 volts) or the point it will no longer will operate it turns off. The key is how do you fire a coil to generate a
spark to the spark plug? Turn the charged coil off collapsing the magnetic field around the secondary of the
coil. Peak load on the battery occurs as it approaches the first compression cycle and is near TDC. If the
voltage falls below the dropout voltage of the ignition at that point the ignition turns off in turn shutting the coil
off and a spark is generated. If the time the spark is generated happens to be 45° BTDC the fuel in the cylinder
is ignited. Since the engine has minimal RPM's the combustion of the fuel wants to drive the engine in the
opposite direction the starter is turning it and the engine wins. The ignition may only be off for a millisecond, but
that's all that is required to fire a coil. If this occurs, clean all connections to the ignition circuit and check the
voltage to the ignition while the circuit is loaded.
With ignition off and the , get a jumper wire with alligator clips and jumper
the trigger side of the coil to ground
. Turn the ignition
on and with a volt meter on DC volts, measure the voltage at the battery, Negative (black) lead of meter on the
battery negative and the Positive (Red) lead of the meter on the positive of the battery. Note the voltage i.e.
12.5 volts. Then move the Positive (Red) lead of the meter to the positive (+) side of the coil, the post feed by
the kill switch. Note the voltage reading of the meter. If the difference between the battery voltage and the
voltage at the coil is more than 1.5 Volts you should clean and check all connections between the battery and
the ignition coil. The dropout voltage of the Spyke Super Comp Ignition 5.0 volts or less and is very low in
comparison to many ignitions on the market.
Do not leave the jumper wire from the battery to the coil in place more the 4 minute if using a
3 Ohm coil. This jumper wire turns the coil on to load the circuit for the test. The coil will get hot and damage
the ignition and/or the coil if left on.