Thanks for the advice. The Yanmar manual shows no-load max is 3800. I just got a digital optical tach so I'll check it out.
That is a fancy piece of test equipment... do you you work on gennys for business or just a hobby?
So much happening lately i forgot about your Yanmar.
Both, as best as i can, side job, mostly self taught, the newer gennys, forget it, cheap computer controled.
Things has changed very dramatically in the past few years as far as the economy, cheaper to buy new then used now so,... wanted to move up into prime movers but never really happened.
Nothing fancy about the meter box or control panel if you would, hertz, volts and amps for single phase, was going to build another for dual voltage and higher Kw/amps.
3800 is fine, valve float on those is not until around 4200 or a little more.
Do not allow it to idle for long, especially in the winter, keep it loaded, if you can grasp the cylinder with your bare hands with out burning yourself it is running too cold, load it up, cylinder bore glazing and decoking is not fun.