Re: What regular main is needed on 1982 70hp Johnson
Drain the carbs (easy to do on that motor), then crank it for ten seconds or so with the choke on to pull any gas out of the low-speed circuits.<br /><br />Replace the water pump impeller unless you're sure it's just been done. Check that the hot horn working.<br /><br />Drain & refill the LU fluid at the end of the season, so any water in the LU won't freeze and crack the casting.<br /><br />Those are good motors. The weak spot appears to be cooking a cylinder, generally the middle one. Overheating on a two-stroke can occur due to lean mixture or too much timing advance (amongst other reasons). A clogged main jet will let that one cylinder run lean - that's why you want to run fresh, non-gummy gas. Draining the carbs at the end of the season keeps the mains from clogging with gummy gas. There are (if I remember right) service bulletins describing richening the jet on that middle cylinder, and backing off the WOT timing a couple degrees.<br /><br />Keep the engine from full-throttle lugging. Prop it for 6000 with a light load. Decarb if it hasn't been done in a while.
