I have a '90 YZ125 and run it at 32:1 with Valvoline TC-W3 motorcycle 2 cycle oil. My manual says to run it at 24:1 with Yamalube and 20:1 with castrol oils. This sounds incredibly rich, every one I've asked says they run thiers at 32:1. Am I supposed to run my bike around 20-24:1, and is the oil I'm using okay? Any help to clear this up would be appreciated, thanks.
manufacturers are very generous with the amounts of oil.Too generous, you'll probably foul plugs at 20:1.
I have always ran mine at 32:1 and their just fine (knock on wood--tap,tap)
If your bike is tuned well running 32:1 and you switch to 20:1 you will not foul plugs. You will find the ratio to be way too lean.
s.d.duner, it sorta feels like it should be that way though, huh?
mdkuder, You sure stress 40:1. Is that your lucky number, or is there some secret about 40:1 that we should all know about?
Yes, you need to say more.
My manual says 24:1 but with the quality of synthetic premix today there is no problem moving the ratio up. I run 40:1, with this ratio I use less premix and I find that that is what the bike really likes.
To emphasize what Jaybird said, Rich and Lean refers to the amount of gasoline in the cylandar. So by moving the premix ratio from 24:1 to 40:1 you are actually making the bike more rich. I know it seems ass backwards but that's just the way it is.