1975 merc 850 advice

Hey, new to posting here as I'm a new boat owner. I recently purchased an 18ft seaswirl w/ an 850 merc outboard on it. The motor runs and I've had it on the water twice. It haden't been run since 1999 before recently. The guy before me took it to a mechanic to have some wiring fixed and he also checked the compression which was all good. My question is I know I should pull and clean the carbs because if I lean out a piston I could really mess things up, but if I've had it out and run twice and it runs nice, do I need to? Or can it wait until a winter project? Also what would you recommend to add to the fuel to make sure things are clean inside? Specific directions as to additive ratios would be appreciated. I pulled and cleaned the fuel tank and replaced all the fuel line and added an inline filter as well. Any other adviced for a new boat owner would be appreciated as well. Thanks


Todd Godfrey

Re: 1975 merc 850 advice

Todd, I do not recommend any additives be reguarly added to fuel. If there is some slight dirt (realy slight) in the fuel passages, some seafoam, might clean some of it up. Obviously additives do nothing for air passages. If that motor has sat for any length of time with fuel in it, the carbs are likely dirty and you could cook a piston.