Makaveli 160

Hi, New to the forum and after some advice please. I have a Cen CTR 5.0 I believe this has a Rev-Line .30 Corsa Engine bought many years ago, haven't used in a while and having some issues. I'll try to keep it as brief but informative as possible. From my experience and many hours trolling the internet and youtube I think it may be an air leak issue (bearings or carb) and/ or piston and sleeve?? First strange symptom I need to know if its normal (which comparing to the exact same model my friend has, he doesn't experience) is that I can hear a very distinct 'hissing' / 'air puff' noise when pulling the pullstart gently when the engine turns over? This seems to be coupled with fuel leaking from behind the flywheel (much less so, once I found the flywheel was loose and dismantled to tighten). Which makes me wonder if the front bearing is faulty? Although the sound seems to come from the air filter / carb, less noise when removing filter and covering the venturi opening with my finger. Another symptom is it will start literally first pull (when cold) and idle for a while, but then usually dies after around 15-30s. But doesn't want to start well at all when warm or once ran. Could this be a possible piston and sleeve issue, although the compression is good? But again once started does leave a line underneath the flywheel of light spray, not sure if this is because its a little too rich or an issue? All settings have been returned to factory settings and is running a little rich. Although it seems to give symptoms of running lean. After running a little while it also borderline floods and I can turn on the side and fuel dribbles out the exhaust. Currently running on Optifuel Optimix RTR 20%. Before taking to an rc shop just wanted to see if anyone had any ideas as I have racked my brains and tried everything so far. From googling people say the front bearing isn't really an air seal as such, but is sealed via the fuel and oil creating a barrier to seal it? Is it worth dismantling again and using the soapy water method to see how much the bearing bubbles? I have had it running a few good times idling, but again it will run and drive, but if i open the throttle up quickly (rather than smoothly) it will konk out and not start again. Any ideas appreciated. Thanks in advanced. (Possibly failed keeping it 'brief'...)