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your thoughts on this i herd correct premix levels on bottle burn best. I for many years living in colorado and racing, the jetting capital of the world imo. I would adjust my premix ratios trying to get bikes to run right more gas less oil and all ways a little rich even with lot's of jetting airscrew adjustments ect i herd a guy talking about premix that it burns hot so less oil is rich? correct premix ratio 32:1 hotter then say 40 or 44 to one right if this is true i'm been trying fine tune premix ratios that way was wrong and to lean that way was stupid on my part he said use ratios on bottle only for best results on clean hotter burn.DAMM thanks Wes old bones in colorado.

When one is referring to the mixture, less gasoline is leaner. More gasoline is richer. The leaner / richer refers to gasoline, not oil.

If the engine is getting too much fuel, it is running rich. Running lean is too little fuel.

And it's opposite of what you would think in reference to the oil. It's about the viscosity of the mixture, going through a fixed orifice (the jet). The more oil, the thicker the mixture, which in turn will not flow through the jet as easily as a thinner mixture, meaning it will run lean as it's not getting as much of the fuel mixture. Whereas less oil makes for a thinner mixture, which will flow through the jet easier, resulting in more fuel and running rich

I read some oils burn at a hotter temperature while others vaporize more completely at a lower temp. How might that affect jetting and or engine protection. When running Maxima 927 I noticed less spooge then my usual Honda HP2 all else being equal jetting, altitude, and riding conditions.

It took me forever to wrap my head around it.

thirdgenlxi is right. I finally thought of it like a milkshake. Thinner can flow through a straw more easily. Thicker is slower. (unless you have a 55 pilot or Mcdonalds big straw)

And all of that is why you pick an oil, pick a ratio and stick to it. Changes to either affect your jetting.

I don't believe it has anything to do with less flow thru the jet. It flows the same but with more oil there is less fuel in the mixture going thru the jet. That makes your jetting leaner

I'm going to have to agree with Roy here. It is simply a matter of how much gas vs oil is in any given amount of fuel mixture. The more oil, the less gas and therefore the leaner the mixture.

then again, that may be true

How about just using AMSOIL Saber at the recommended 100 to 1 and not worrying about richer or leaner. That has worked for me for 35+ years.

What kind of three wheeler and how hard is the engine ran?

That may work but I'm just not comfortable going 100:1. I can only imagine the jetting changes needed considering that's a much richer mixture than 32:1 or 40:1.

The dude that owns a local bike shop convinced me to run the Sabre. I was scared about 100:1, so I am running it at 80:1. I was hesitant at first, but the bike runs awesome. He swears that when I take it apart again, everything will still be clean and the KIPS valves won't be gummed up. We shall see I guess...

doakley wrote:I'm going to have to agree with Roy here. It is simply a matter of how much gas vs oil is in any given amount of fuel mixture. The more oil, the less gas and therefore the leaner the mixture.

Actually let me be more specific. Rich or lean pertains to the ratio of gas to air (actually oxygen in the air). More gas = richer; less gas = leaner. This is controlled by carb jetting. If you use more oil in your premix then there is less gas. Less gas for a set amount of air (oxygen) means the gas/air mixture by definition is leaner. Your fuel/oil premix ratio should be done with engine lubrication in mind, not lean or rich fuel/air mixture. For this reason you should always mix your oil at the ratio recommended by the OIL manufacturer as all oils are formulated to be mixed at specific ratios for optimal engine protection and lubrication.

If you keep your fuel premix constant, the only reason you should have to change jetting is due to altitude changes. Why?
Because air at lower altitudes is more dense than air at higher altitudes. This means for a give amount of air pulled into your engine (say 200cc) you will have more oxygen molecules in that 200 cc at lower altitudes than at higher altitudes. This means if you are jetted correctly for say sea level (dense air) and take your bike to the mountains at a higher elevation (less dense air) you will have less oxygen available and therefore your jetting may be rich (too much gas for the available oxygen). Varying between sea level and about 4000 ft, I have not noticed a problem with the jetting in my 220, FWIW.

BTW, this is why aircraft have a separate "mixture" control lever. As the airplane climbs higher into less dense air (less oxygen available to burn) the mixture control is adjusted to reduce the amount of gas fed to the carburetor to maintain an optimal gas/oxygen ratio. This effectively "rejets" the airplane's carburetor in flight.

Tyl3r wrote:The dude that owns a local bike shop convinced me to run the Sabre. I was scared about 100:1, so I am running it at 80:1. I was hesitant at first, but the bike runs awesome. He swears that when I take it apart again, everything will still be clean and the KIPS valves won't be gummed up. We shall see I guess...

One of my buddies that I ride with runs 100:1 in his '03 YZ-250 using Opti 2. He hasn't had the bike a crazy long time but so far he's had good luck with it, and hasn't had any problems at all. He keeps telling me to try it, but I just have a hard time bringing myself to run 100:1, lol..... especially for street riding at sustained higher RPM's. Hard to stray away from what I've been using when I've gotten this much use and good luck out of it so far