Hi.
I actually run 14 oz. oil per gal w/o problems. Do not run them @ 50 to 1 on the stock rod, not enough oil if it ever goes lean. Remember, the oil is your ONLY safeguard against HEAT, which robs power. The engine will run great and will never breakdown using 10% oil, but use less oil (less than 10 % overall), and you WILL have a problem.

Re. sparkplugs: I've run the Rimfires (1/4x32 )and 10mm plugs. Go with the 10mm plug conversion, as the Rimfires are somewhat inconsistent, plus they are VERY expensive (Avg. $15.00 ea.).

Good luck with your Supertigre.

Starfighter (Ken)