Hi there ,I have newish 20hp Yamaha 4 stroke, after a run , I suppose when it gets hot, it revs higher than normal at idle, any one else had this issue !
Idle speed should always be set to the makers figure when fully warm and usually in forward gear. It is often lower when the motor is cold unless you offset by keeping the choke out a bit.
The only change I sometimes make is if the idle is supposed to be 850rpm hot and in gear but when in the mid period with the choke in but not fully hot you find a tendency to stall going into gear just set the idle to 900-950rpm.
Ahh well my experience of efi outboards is that they should have spot on idle speed control. Hot, cold, in or out of gear, trolling in gear at idle then my Suzuki 20 was exactly the same figure. So the spec figure for efi might be given when in neutral.
Might need a diagnostic plug in unless there is some reason this particular model does this... perhaps ring the dealer or email Yamaha.
A cheap £10 tach to get the actual figures might be a useful start.
