over revved?
impossible! they cant! they wont! not if their relatively stock. even down a steep hill they hit a certain speed and NOTHING will make them go faster. other than some porting etc... so something else was the problem, which is more than likely anyway.
but, thats off topic...
4 strokes... if its a brushcutter/blower type engine, it will be around 80ml-120mL. a 1L bottle of oil lasts a long time, BUT... when you first run it, let it warm up, idling, for at least a minute. then full load the thing, dont baby it. that doesnt mean full speed, that means full LOAD. bog it down. just for the first five-ten minutes.
then change the oil.
ten twenty minutes of use, change it again.
use a whole litre of oil in the first few hours of use, then basically forget about it, every 20-50 hours.
any old oil is fine, dont go wasting money on fancy synthetics, especially on that first litre. always let it warm up a bit before using it.
if its an industrial/stationary engine, do the same thing but they can take from 150mL up to 500mL or so...iunno, havent played with that particular engine... theyre all much the same....piston, valves, camshaft...
probably has the chinese "torch" spark plug. swap it over to NGK... CR8HS i think they are. it may be an E... (h-1/2" of thread, e-3/4" of thread, pretty sure its the C size though, not a D or anything, definitely wont be a B or A!). check before buying anyways
regular fuel, dont bother with super premium high octane stuff, just use whatever...
you might have to pop the rocker cover and adjust the valve clearance occasionally. other than that, there isnt much to go wrong engine wise...the kit may be the issue though?
4 strokes are fine, they dont buzz, they dont smoke, they dont smell, they dont annoy people. they have little or no scope to modify though. bit of bottom end torque, enough power to lug up a hill when geared right... even accelerate a bit.