Plug problem

[boetie]

Hi, I recently bought a boat with a 8 hp Yamaha. I dont know what model the motor is but it has points. It is a 2 cylinder. I found that the top cylinder is not fireing, and every time I put a new plug in it runs fine, but as soon as I switch off and start again the plug is dead. Can anybody help please? Thanks.

[boats.net]

I don't have any information on a Yamaha 8hp with points but could be wrong plug, point setting or bad points and condenser. Could be low compression.

[boetie]

Plug problem

Hi, Thanks, I think it is the right plug, because it is only the top cylinder that is doing that. Each cylinder has its own points and coil, but only one carb. Could it maybe be the coils under the flywheel?

[boats.net]

Yes it could be a bad coil.