Spark on the 2 strokes

[user 21074]

Do the Johnson motors of the 1980's 20hp/9.9hps or any year of the 2 strokes give spark on each revolution of the crank for each cyl.I have an old motorcycle that has a wasted spark on one cylinder, meaning it fires on both even though one cylinder is not a factor.

 

[Pappy]

The spark on these engines is not a wasted spark. They do fire every revolution as required by 2-stroke design.
Quite a few multi-cylinder motorcycles and other engines have coils with two secondary leads. This saves precious mounting room on the motorcycle and the wasted spark will happen in a cylinder on the exhaust stroke.

This is the engine on my wife, Lesa's Honda Valkyrie. It is a 6-cylinder opposed engine. Only has three coils to fire it. Wasted spark system.

 

[user 21074]

thanks

 

[Sinkingfast]

Pappy.. I thought the 9.9/15's only had one trigger or pulse coil. My buddies has one trigger for a series wound coil and both plugs fire at 180..I do not know what year the motor is though..

 

[crazymanme2]

On around 76 or 77 they had a driver coil under the flywheel.

 

[Sinkingfast]

On my point system omc 15 the magnets are arranged in a n-s then s-n. The current reverses direction for the other cylinder. If the cdi flywheel is arranged the same n-s then s-n I can see only needing one trigger being triggered every 180 for there not to be a wasted spark. :?: