[reelapeelin]

Every carbed Merc I've been in sounds like a dragster fixin' to punch the button...sounds cool at first, but gets old when trollin'...

But, Vic, your question is about idle/cruise and oil mix...if there's a way to vary mixture when you're pre-mixing, I never heard of it...I pre-mixed my 150 Rude for years 50:1 and never had a problem...

One trick my O/B tech told me about when idleing/trolling, TILT motor UP so that back of motor is just above front of motor.to keep excess unburned oil from accumulating in the spark-plug end or "top" of the cylinder which leads to plug fouling...your cylinders are "horizontal"...think about it in terms of liquid runnin' toward the front of the motor rather than the back of the motor where the plugs are....hope I explained that to where it makes sense...won't reduce noise, that's inherant w/that motor, but it will help prevent plug fouling and smoking at idle...hope it works for you... ;) ;D ...