7.% K&B ouboard engine stall

[fmimages]

My engine runs for a few seconds to a minute then dies. I can blip the trottle but when it quits it quits. I started my tuning at 3 1/2 turns to 6 1/2 turns out (high speed needle). It ran last season. I have switched to a higher nitro content fuel with a cold plug (Bryon 60% nitro). I have a new piston/sleeve combo just in case but I think I have enough compression the way it is now. I have no head shims since the squish band that I measure seems gargantious anyway. It was running on 30% nitro and standard plugs before but I want to make it go faster. The engine is old but it has been refreshed. There are no fuel leaks. I was reading in another post of putting some sort of preassure monitor on the inlet fuel hose to see if preassure is the problem. There are no bubbles in the fuel line. I'm stumped. I use a tub of water to test since I don't want to make a wasted trip to the pond. Any suggestions would be appreciated.
Thanks :roll:

[fmimages]

It's a fuel draw issue that I hope is not connected to a piston compression issue. i have no way to measure the exact compression and whether that is in spec.

[MECOA]

Fuel draw is either a carb or air leak problem.

Carb can be debris or spray bar in incorrect position.

Air leak in the lower crankcase area can be from bad gasket to excessive clearence between the crankshaft and crankcase area between the bearings or PTO shaft clearence on the outboards.

http://www.mecoa.com/faq/crankshafts/blowby.htm

Sometimes not noticed on an outboard.