I recently converted a well used ST 2500 to gas. The results were quite suprising.

Fuel - 87 octane mixed with 10% no name brand 2 cycle oil
Carb- Walbro WT 225A with a 1/2 inch venturi.
C&H ignition set at 28 degs. BTDC at WOT
RPM - 7600 settling down to a steady 7400 with an 18x10 APC prop. A smooth idle at 1500 rpm

I then took off the ignition and replaced the spark plug with an O.S. #8 glow plug
Fuel- Morgan Omega 5% nitro with castor oil
Carb was the original 9 mm ST carb.
RPM - 7300. Idle was not checked.

I never expected the gas conversion to out perform glow fuel. Perhaps its the better breathing with the larger Walbro carb and the more precise spark timing.
Any comments?

Dave G.

Your numbers are very common on a big Tiger. Better ignition timing is responsible for most of the increase. For power try Glow fuel and spark ignition.

With my 25cc Homelite...I ran a mix of Glow fuel (Omega 10%) 8 oz and 16 oz of gas (97oct) and spark ignition. It really ran good. Makes your glow fuel go a lot further with pretty good power. Capt,n