Oiled gas question.

[THEFERMANATOR]

Originally Posted by awthacker

My boat not having an oil reservoir, when I installed my 94 Evinrude two-stroke I removed the fuel/oil VRO pump and replaced it with a fuel only pump, capping off the oil inlet to the engine but leaving all of those hoses in place. I premix 50:1. It smokes a lot and I hear the phrase Better Smoke than Broke a lot.

I wonder, since I very rarely run wide open... do I really need 50:1? Isn't that pretty much WOT ratio? Shouldn't I be able to mix 40:1 and be fine and result in less carbon build-up? Doesn't the VRO pump somewhere around 150:1 at idle and 50:1 wide open? What would be the worst case scenario if you were mixed at 40:1 and ran WOT for, say, 5 minutes?

40:1 is richer on oil than 50:1. The VRO is designed to oil around 40-50:1 at WOT(depending on the size of the engine, larger engines pull more fuel and thus the pump richens up the oiling more), and drops down to about 75-100:1 at idle. I've rejetted several engines now to run on pre-mix, and if you run GOOD quality oil they don't smoke bad at all running 50:1 premix. MERCURY QUIKSILVER oil has been the WORST oil I have used as far as smoke goes, and PENNSOIL blend has been the best to keep the smoke down. i'm not a PENNSOIL fan myself, except for 2 stroke oil. In which case I use it in EVERYTHING. Every boat I work on, have owned, and any 2 stroke engine I have or worked on right down to lawn equipment gets it.