which suitable motor

[aramos]

Hi, I was wondering if you can spare me your expertise.

What kind of motor can I use for a spit roast project?

upto 65kg load and about 4-6 rpm.

Thanking you in advance.

[Danger]

Welcome to PF, Aramos.
I'm not familiar with spits. I have a couple of propane BBQ's, but neither has a rotisserie attachment, and definitely neither has the capacity that you specify.
Almost all 115 VAC motors run at 1,750 rpms, so it is simply a matter of gearing to get the speed that you want. They vary in torque ability, though, so you would want something more like from an electric drill than from a blow drier. Come to think of it, an electric screwdriver has even better gearing than a drill. You're looking at double or even triple sets of planetary reduction units. You could rip the lips off of a rhinoceros with one of those things.

[jim hardy]

A gearmotor is what youre after.
On the cheap - if you're okay with using hand tools to make it, an automobile windshield wiper motor and bicycle chain reduction might work. A 6 amp battery charger will power it.