Hi I have got an out board motor (seagull forty plus, if that makes a
difference) that works fine but annoyingly has no electric cut off
switch. This means that to shut it off or stop it you have to turn
down the throttle to the idle position and either starve the carb of
air by placing your had over the air intake or turning the fuel tap
off and waiting for it to run out of petrol. This may not seem to much
trouble but you the have to go back through the priming procedure each
time you want to start it again, and as this has to be done by leaning
out over the back of the engine and boat is awkward to say the least.
The trouble is you cant leave it ticking over at low rev's as the
impeller doesn't throw the water around at the slow idle speed you
need the forward motion to help the circulation.

What I would like to do is split the ignition lead (or jion two
leads) and put in a cut off switch? That way the engine will stop
instantly and should start first pull when needed again.

Will this affect the engine in any way, as the coil is £120 to
replace that's if you can get one.