I've been flying nitro planes since I can remember, but I'm now gettinmg into larger scale planes w/ gasoline engines... I've found some used ones;
1 is an 18 cc Poulan converted engine w/ a timing mechanism on it, 1 is a US 41 w/ a spring starter on it, 1 is a zenoah 23...all are used, all different...Now I am seemingly lost on a few things:

1). what is a proper voltage source for a gas engine?
2). Should each engine take a different voltage ?
3). Should this battery be different than the receiver battery?
4). Gas top oil ratio ?
5). Best priming/ starting procedures?
6). Are there any wiring diagrams out there for optimum set ups ?
&). Any other tips ?

1) voltage depends upon the manufacturer of the ignition unit, but most are 4.8 V. A gas engine with a magneto ignition does not need any battery at all.
2) see (1)
3) A typical receiver battery is fone for ignition. Needs about 800 - 1200 mAh capacity. perhaps more for a twin.
4) this is a function of the oil, not the engine. Typically 30 - 1 or as much as 100 - 1.
5) close choke. turn on ignition. throttle at fast idle. flip prop until pops. open choke. flip prop until running. about 10 or 15 flips total
6) wiring for electronic ignition is simple. battery to switch (with charging receptacle) to ignition unit.
&) gas is probably "easier" and more reliable than glow in the long run. glow engines tend to be more tempermental.

Make sure the Poulan includes and ignition system. May be what is refered to as "timing mechanism", may not be. Generally the electronic ignition are separate from the engine, while a magneto ignition will be mounted to the engine. Electronic ignition is "on" by connecting power to the battery. Magneto is "off" by grounding hot wire to engine case.
Answers were pretty well covered by previous poster.

Thank you! Thank you thank you !

Most helpful!

I actually staretd 2 of the three this morning, and aside from being a lil' nervous of the larger blade..It seems pretty easy and stright forward.

3 last questions (for the moment):

I'm planning on repainting over the mono-coat, can I use Testors (plastic model) enamel paint ...or what's a recommended paint on gas planes ?
Do I need to put Top Flite fuel proof spray on it ?
What's a good cleaning agent for your planes ?

I had very little residue from one engine, just an incredibly small black splatter.

You can out just about any paint on a gas-powered plane as the exhaust is not as problematic as glow. You will get a little oil from the exhaust but only a fraction as compared to glow. I use 409 cleaner or equivalent. Actually my gas plane I generally throw back in the car without any cleanup at all.