Good explanation of oil mixtures

[Makotosun]

I found this looking for something else. Seemed useful.

Link to article is => https://dirtbikemagazine.com/mr-know-it ... explained/

[Bill2001]

Good article and good website.

On the oil premix ratio it seems to me that the initial premix ratio should be determined by the oil manufacturer. For example, in the '60's when we used 30w engine oil as the premix, that ratio was vastly different than a modern 2-stroke dedicated premix oil suggests. I would tend to start with that ratio.

Question is, how do we tell if the premix ratio is correct?

[ossa95d]

Maxima provides these pre-mix ratio recommendations for their oil at the bottom of the Oil Migration Chart.

[Joe Ormonde]

To show you all what oil can do to jetting, read this ! I hate to sound like a broken record, but here it goes. I bought my 93A brand new and still ride it. My jetting at 4000 ft. is 30 pilot, N8 needle jet, 4D3 needle #3 position, 2.0 slide and 180 main. Oil Ratio:24:1. It has the same VM24 carb and pipe it came with new. The pipe has a 8 inch J&R silencer that has also been on the pipe from day 1.The engine is bone stock. Lets back up the clock to 1974. I reed valved it, used Torco at 24:1 and the jetting was: 30 Pilot, N8 Needle jet, 4E1 needle #2 position, 2.0 slide and 210 main. The Altitude in Chino CA. where I lived then is about 750 ft. above sea level. A little shop called Cycle Rider had oil on clearance so I bought 4 Quarts. To get my little Rat dialed in with that oil here is what had to be done. Pilot Jet, 35. Needle jet, N8, 4F6 Needle#2 position, 2.0 slide and a 250 main jet. What oil was it? Castrol R40 mixed at 24:1. Joe Ormonde.

[DG29]

Hey Joe,
That Cycle Rider is my local go to shop. It seems like the majority of people here go with the Yamalube. I picked up some but have yet to try it out. It also seems that most run their bikes at 32:1. I ran my 93a for pretty much a whole vmx season on Maxima K2 at 50:1 on a vm 24 with a 30 pilot jet and a 170 main. It's the Rat that I've had since I was a kid. Your 93a sounds very similar to one that I've recently put together. Do you ever race yours?

[Joe Ormonde]

Never ! Cycle Rider was GREAT ! They did jet the 93A too rich, but I think it was jetted for 16:1. My family still lives down there. To show just how much that area has grown, I graduated from Mountain View Elementary in 1971 with 8 students from the 10 Freeway all the way to nearly Norco. Modern Oils are better than the old school stuff, but it`s just my preference to mix at 24:1. Check this out! In the summer of 1974, cows were dropping dead from the heat. By the end of the summer, the XR75s and my Super Rat were the only things left running. ALL my riding buddies wouldn`t ride because it was so hot or their engines FRIED. How hot was it? Look up Ontario CA High Temperatures 1974 and you will all see why i`m a heavy oil user. Let me list them: June 1974 120 degrees .July, 129. August 129. September 102. SEE ! Joe Ormonde.