mad_max_76
New member
I recently bought a used Yamaha 2 stroke 15 hp outboard, a 1993 15MSHR. It ran fine for a couple of months but is now having problems starting (and sometimes dies in neutral/idle), so I'm trying to trouble shoot.
I couldn't for the life of me find a manual specifically for this model, but similar models take NGK B7HS-10 plugs. I can't find anything on the plug gap specific for this model, so I assumed that it was 0.035-0.040" as for similar models. However, when I removed the plugs to change them and checked the gap, they were less than 0.03 (perhaps 0.028 or 0.029). When I swapped these for those I gapped at 0.037, it ran even worse.
Is it possible that this particular model takes 0.028" gap plugs? That's very strange for a 15 hp 2 stroke Yamaha, all of the other 2 stroke 15 hp models (except the E15) listed here have gaps 0.035 or greater
https://www.marineengine.com/parts/ngk/yamaha.html
I couldn't for the life of me find a manual specifically for this model, but similar models take NGK B7HS-10 plugs. I can't find anything on the plug gap specific for this model, so I assumed that it was 0.035-0.040" as for similar models. However, when I removed the plugs to change them and checked the gap, they were less than 0.03 (perhaps 0.028 or 0.029). When I swapped these for those I gapped at 0.037, it ran even worse.
Is it possible that this particular model takes 0.028" gap plugs? That's very strange for a 15 hp 2 stroke Yamaha, all of the other 2 stroke 15 hp models (except the E15) listed here have gaps 0.035 or greater
https://www.marineengine.com/parts/ngk/yamaha.html
