I'm about to break-in my first 4-stroke too, Saito 100. The book tells me not to exceed 4000 rpm for the first 10 min of operation to allow all parts to mate properly with good lubrication, & that due to the excessively rich mixture I may need to leave the glow heater attached. After that first 10 min run I can start leaning out slightly with each tank of fuel. Then it says that 40 min is considered sufficient time for normal break-in prior to first flight.

Now I'm one of those guys that darock is referring to. I can't tell by ear what 4000 rpm is. I thought as long as I kept it at about 1/3 throttle I should be ok. They show an rpm range of 2000 -11000 with a 14x6 on it so 1/3 should keep it under 4000 right? Without a tach, I figure all I got to work with is math. Because I don't have the experienced ear that most of you guys have.

So what do ya think is this theory gonna work-out ok for me until I can get a tach?