ORIGINAL: SuperAirborne
Hi Folks
I have an ASP .91 4-stroke engine swinging a 13x6 prop. I want to know what the ideal idle speed should be, as well as the maximum rpm. I'm new to 4-stroke engines!
Your inputs would be appreciated!
Cheers
G'day Mate,
A 13x6 is too small for a 91 four stroke, try a 13x8 up to a 15x6, your idle speed, is the lowest you can get, & still pick up to full speed without hesitation, of course after it is run in, & the low speed mixture is set.
Top speed is usually no more than 10,000RPM, in the air, so allow about 500 or so revs as the engine unloads.
This is only a ballpark figure, it is not cast in stone, but is a good guide.
Remember, a four stroke will & needs to swing a larger prop than the same size two stroke.
They have much more torque, & will be damaged if they are run too fast, with a prop that is too small, two strokes don't have valves & push rods, to get bent & damaged, four strokes do!