Jaybird, I only used 20:1 as a reference, i understand theoretically more oil = hp. The biggest hp gain/loss is the 32:1/40:1 range though. Now back to carb, the first step in 2-stroke jetting is picking your oil ratio. I would say to stay at manuf recommendation, but run what you want, everone has thier own preference. For longetivity of engines and ease of jetting I prefer 32:1. Once you choose oil/fuel ratio stay with or it can effect carb jetting. Now that you have lets say jetted your fuel mixture, you have to get the proper fuel mixture/air ratio through the carb. X amount of your fuel mixture will flow through a lets say a 100 main jet. If you use 32:1 you will have more gas and less oil than 16:1 which would be less gas and more oil than 32:1. Therefore if a bike is properly jetted at 32:1 with a 100 main, and you switch to 16:1 you will lean the bike out, so you may need to increase main jet to lets say 105 to have bike properly jetted again. The end result from going 32:1 to 16:1 is you may need to increase main get to get proper air/fuel ratio to cool combustion, but you will have more oil in the engine. The carb atomizes the fuel mixture and is carried to the crankcase where engine heat vaporizes the mixture which allows the oil to fall out and do it's job of lubrication. So to answer motometal you need heat to vapoize fuel, but once you have enough heat to do that you dont need no more, raising the temp would only lead to possible overheating of the engine and poor performance. I dont want to write about the fuel faster vaporizing, but your right a faster vaporizing fuel could tend to lead to better lubrcation but i cant see where this would be an issue with any current fuel. Now all the oil we have put into this engine will go through the engine if we put too much oil in engine it will not be properly burned so we get the spoog everyone talks about, plus it will tend to lead to a fouled plug. So to burn the oil you would cut back on the main jet which would decrease our fuel mixture letting less oil and gas through carb. Less gas would elevate combustion temp, helping to burn oil and since theres less oil it can be burned better. Get that? Now if we use 16:1 instead of 32:1 this is what will happen. We have more oil in gas, this will take away from fuel to air ratio because the fuel mixture has to go through the main jet, so to get the proper fuel to air ratio to cool combustion we increase main jet, which allows more fuel and oil to enter engine. But wait now we have more oil that will need to be burned. The problem here is if we decrease the jet size to burn oil we could overheat the combustion chamber, and if we stay where we are we might not be able to burn oil and can foul plugs. Some bikes can run there fine at high rpm but it's the low rpm that gets you. thats where good carb tuning comes into play. Main jet is set for wot only. These bikes are made to run not idle, so at 16:1 wot your bike may fine, but now you go into woods you dont have heat to burn oil so bikes start to load up. you can try smaller pilot jets, or larger diameter needles help with this but there again you have to be able to burn oil or here comes the spooge and a fouled plug. So it may be better to tune and engine with 32:1 not so much for wot but for low rpms because you will need to burn less oil to keep from fouling plugs. Thats why the first thing people do is cut back on oil like 40:1 because you have less oil to burn and it seems to help thier situation. Where if they had jetted the bike properly by using main, needle, pilot, mixture it would've made the bike run better to begin with and still gave better lubrication & hp. Now jay bird and that rod thing alot of the very high rpm engines can create heat that can be aggrevated by excess oil. Some of the smaa engines turn 14000+ rpms almost twice as fast as a 250. Smaller engines use smaller parts spin faster so friction and oil temps can become sort of an issue, they are kind of on the edge in a sense more so than a 125 or 250. Too much oil can actually add to the friction the bearing has to overcome to rotate freely and also retain heat in the bearing. That said if you take all the factors a small engine has to endure adding friction to a bearing can spell disaster. Most high speed 2-strokes recommend 40 or 50:1 but yet turn much greater rpm tan a 250. Another aspect of this friction factor is you have a 125 and 250, you run both 32:1 and put the same hrs on both, the 125 would have greater internal wear because of higer rpm causing more friction. Bottom line manufacturers are'nt asking us to run a crazy ratio of 100:1 so we blow engines up. They recommend a ratio they believe will satisfy the engine in the operating range and limits it was designed for.