I just put mine on the Smaragd this week after I had an accident with it last fall, on the Focus not the engines fault mine for not checking the low idle switch first it has run flawless with 2 OS F plugs never had any luck with the A5 plugs wasn't consistant till I changed to the F, I'm running Coolpower 15%, I live in central Indiana and it's been hot high 90's very unusual for us, the one difference this time I'm running the carb off the OS RX and it is perfect not that the original didn't just wanted to see how it done, because it's a dropin fit, I'm running the 17 X 12 apc prop, I'll say this it has plenty of power, much more than the OS RX. Last fall I tried the 15.75 X13 3 blade and it done fine but was only turning about 7000 rpm but it is to much prop for the heat of summer.
Steve Maxwell