ho w do you know?

I have a 1994 Merc 150 Black max and the previous owner(s) removed/disabled the oil injection pump. I just add the mix in at 50:1 (gas to oil). It really does smoke v.s. a newer 2 stroke. To a point it will choke me out if it leave it idle too long at the dock.

I know cause I have a keen sense of observation. I have a couple engines with the oil infection removed. Very smoky at idle. Oil injection leans it down a bit for idle when it isn't as necessary. I pre-mix 40:1 and can kill a mosquito better than one of those smog trucks.

I pre mixed 50:1 on both my modded EVINRUDE and my MERCURY before it, and never had horrible smoke. I always used PENNSOIL PREMIUM PLUS synthetic blend. I tried the MERCURY QUIKSILVER oil and it smoked to high he!! on it. The MERCURY was injected so I didn't do anything to it for idle mixture, but my EVINRUDE did get rejetted to help with the loading up at idle. I used to troll it for hours on end, and it would smoke, but never to the extreme it was unbearable. When you get em set up right and use good oil, it isn't horrible. Will it ever be as clean as an oil injected engine, no. But they can be made to run decent on 50:1. I don't like 40:1 because it raises the viscosity of the fuel which actually leans out your mixture, not to mention there is more oil and less fuel which also leans out your fuel mixture, and oil burns hotter than gas does(and it leads to more carbon build-up). Unless you plan on spinning one to over 6500 or so, then go to 40:1 and make sure and use ring free or sea foam in your fuel.

Not to highjack the original thread. I wonder if it got resolved?

Ferm, 50:1 is enough, I know, but I can't help but think I get better life out of my 40:1 mix. I too have run Penzzoil, never let me down. Both oils, smoked like an old oiler at idle. Not like running double oil for break-in. You think 40:1 is a damaging level of pre-mix? Viscosity? not much due it couldn't flow enough volume thru the fuel lines on the old 250 EFI Merc. It is incredible how much fuel it could go through in a hour, full tilt, with a big prop.

If you jet accordingly then 40:1 is fine, but if it is jetted for 50:1 then it isn't helping it any at all. I know the 1.6L sea drive I had would run hot if ran 40:1 in it, but on 50:1 it was fine.