Just finish a revamp on a classic project...whats the RPM on these? no joy online can get close enough by ear but she has mileage and would like to keep it right. thanks
9D902 2006B3 0210285
All vertical shaft engine spin around 3000 rpm.
If it is on an 18" mower 3400 is max speed as it gives a blade speed of around 20,000 ft / min which is the old max allowable blade tip speed.
The 4 strokes generally spin a bit slower 2800 to 3200, blue smokes 3,000 to 3,600.
So if you rreally want an exact speed, work out the blade tip circumference in feet, divide 20,000 by it and that is the rpm if the blades are bolted diectly to the crankshaft.
Apparently there are a few apps for the BatPhone uses that make them into a 1/2 decient tacho might be worth a look if you have one of those phones that do every thing except make phone calls.