Brand new engines require a ratio of 28:1 for break-in...This is done for 4 complete tanks of fuel....Then after the engine is broken-in you should run it at 40:1 for safety 42:1 for a lil more pep and 50:1 for performance
The engine you posted is a piston ported engine and grey case engines usually come on the X7 and cateye
The engine you posted is a piston ported engine and grey case engines usually come on the X7 and cateye