Re: modifying lawnmower engine...
you should have a control attatched to the handle on the mower with a long cable going to a lever on the carb, (or into the barrel on top of the car (depending on the carb type), this is your throttle.
your throttle will control the engine speed.
the screw that you mentioned before, (idle control) will determine how fast the engine spins when no throttle is applied, this should be set to a setting that will keep the engine alive but not revving highly when no throttle is applied.
you ask how to control the RPM, well the RPM is controlled by the throttle, open up the throttle and the engine spins faster, close the throttle and it spins slower.
as for mounting, as engine will work at practically any angle, however if it's a mower where the blades are mounted directly under the engine that it's not ideally you'd need one of the older style ones with the cutting drum that spins as the engine is mounted at the correct orientation for this already.
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Im sick of people saying 'dont waste paper'. If trees wanted to live, they'd all carry guns.
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