ORIGINAL: TimC
I don't know if this is typical, but my 4*60 ARF came out very tail heavy. If you go with a 2-stroke, one of the heavier .75's or .91's would help it balance.
I put in a larger batt pack (4.8V 1400mah NiCd) and pushed it all the way to the firewall. I also have a 16oz tank. The cg is at 3 7/8", the maximum in the recommended range. I did have some lead weights up front (1/4 ounce or so) which I removed after some time