Oil fuel ratio modern donks

[dnej]

My old donk used 50:1 pre mix.
The new Yamaha,is non pre mix.

I understand the ratio is variable,depending on the position of the throttle.
That is at idle 100:1,and WOT,approximately 50:1.
What is the principle,that makes this mixture change? Is it simply more revs,more oil pumped in,less revs less oil injected?
Thanks
David

[Noelm]

there is a lot of "things" that determine the amount of oil 'injected" into the motor and different manufacturers use slightly different ways to go about it, but it is usually very reliable and less poluting than the old mix your own system, some motors will run less tha 100 to 1 when at idle and move up to 50 to 1 at high speed, it is all controlled by the majic of electronics and "black box flight recorder" type stuff, coupled to engine revs and vacuum etc.

[dnej]

Thanks for that.
David

[griz066]

Sounds like you have got a handle on it