If it is running too rich, going from 32:1 to 40:1 will exacerbate the problem. Besides, wouldn't the best way to correct the problem be to rejet the carb for the mix, not change the ratio of the mix for the carb?
It seems that 32:1 should work okay if the bike is jetted correctly. I use 40:1 on my 98 KX250 because 32:1 seemed like overkill. (that and one bottle in my 5 gallons gas tank equals 40:1) Once the was jetting set, ...finally, the bike runs great with very little spooze.
I guess the oil works good. One top end job since switching and everything looked good.
Let me know which snake oils are you talking about? What oils have you had bad luck with? Just wondering why you started to use the mobil oil:think I do argee about the over price on some oils that some shops carry thats why I don"t buy Motul 800 and high price stuff. I use the yamalube 2-r oil and the rep and the at $5-$6 you really can go wrong with that. Good stuff;)
I run 28:1, one of my other riding buddys runs 25:1. We have no spooge or fouling probs. We spend alot of time jetting though, once you get the bike jetted correctly you can run higher oil ratios without any probs. It does give you good better ring seal and I like to think that it protects my motor better.
That $3.50 price is that for a pint or a qrt. The $5 that I pay for yamalube is for qrt. If that is for a qrt let me know where I can find it because none of the autozone carry it around here in so cal.