February 6, 200917 yr Sorry if this has been asked a million times but when using modern synthetic oil do you use a bit less or does it muck up the mixture? So basically what ratio for the old Mont. Thank you.... Steve
February 6, 200917 yr Sorry if this has been asked a million times but when using modern synthetic oil do you use a bit less or does it muck up the mixture?So basically what ratio for the old Mont. Thank you.... Steve You can use less of a modern semi-synthetic or semi-synthetic two-stroke oil than what you would have used of a basic mineral-based two-stroke oil in the 1970s. How much less depends on how game you are, how hot it is where you ride, how you ride and many other factors. I live in a very hot place and sometimes get my 1970s trials bike motors very hot so I use 3% (33:1) semi-synthetic. Good quality modern oils produce very little smoke if the jetting is good, even at 3% mix. You have to make a very large change in oil/fuel ratio to affect the fuel/air mixture. If you used 5% (20:1) in the 1970s and want to run 2.5% (40:1) now with modern oil, you will probably not make a detectable difference to the way the motor performs.
February 6, 200917 yr Author OK thanks feetup. I did a search and there are a lot of different opinions! I thnk I will start at 50:1 and see how smokey the bike is. In the UK it doesnt usually get too hot, and I'm not the type to sit stationary in a mud hole with the throttle pinned.... On my modern Gasser I was using 70 or 80:1 and that seemed perfect as you would get a reassuring haze when revved but otherwise clean running. But I understand air-cooled like a little more oil. Steve
February 6, 200917 yr I have been using a 50:1 mixture of full synthetic oil (Mobil 2T) in my Suzuki RL250 for a couple of years without any problems. Back in the old days when people just used 30 weight motor oil we would mix at 20:1 - but these old oils were not as good as the modern synthetic oils and needed to be mixed that way to properly lubricate.
February 6, 200917 yr I have been using a 50:1 mixture of full synthetic oil (Mobil 2T) in my Suzuki RL250 for a couple of years without any problems. Back in the old days when people just used 30 weight motor oil we would mix at 20:1 - but these old oils were not as good as the modern synthetic oils and needed to be mixed that way to properly lubricate. The old oils seemed to stick to the bearings for longer, even leaving for months at a time seemed to cause no problems. 32 : 1 conventional 2 stroke oil for me.
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