What spark plug would you recommend? Champion J8C? I think one motor had J4C plugs (the Indiana motor?)
The recommended spark plug was a J4J, which is now J4C. (The C means Copper electrode). For your elevation, a J6C would be a better, hotter plug, and the J8C hotter yet. Which you use depends on how you use the motor. If you are trolling or idling a lot, then the J8C will likely be best for you. If you are running at high throttle a lot, the cooler J6C may be better. If the plug is too cold, it will foul sooner and need cleaning more often. If the plug is too hot, you can get pre-ignition (knock or ping) which is bad for the pistons – like hitting them with a hammer. You can’t always hear the knock/ping in a 2-sroke outboard, so you often don’t know it’s happening. Spark plug heat range has nothing to do with how hot or how fast the engine runs. It is all about the temperature of the spark plug’s firing electrode tip to burn off deposits and keep it from fouling. Unless you do a lot of idling/trolling, I’d start with J6Cs and if you start to get bad idle from fouling in a short time, and they look a bit black and sooty, then go to the J8Cs.
Dave
