Hi guys

I am running a converted Saito 150 engine (with Prospark).
The engine runs fine with glow fuel after conversion (with spark ignition).
When i changed over to gasoline, the engine splutters and dies.
I have tried various walbro carbs, but it still quits after some time.

I suspect my octane level is too high. I can only get 92 Octane.
The recommended is nearer to 86 Octane.

So how do we lower the octane of a fuel?? From 92 to 86?