Can't start my Webra Speed 35 (Heli) Airboat
 

Bit of a long story on the boat but the engine turns over fires a few times then dies. Priming makes it fire a few more times before it dies again which would indicate fuel starvation. Glow plugs good, blown the carb through needles out all looks clear, high and low set at 1 1/2 and 1 1/4 turns out respectively. Perhaps the carb is leaking air. Any suggestions would be very welcome and much appreciated.

Your needle settings are likely too lean. Open them up a couple more turns and try again.

This engine has a large bore carb. make sure you run pressure. In a heli model the fuel tank and engine are at the same level.

What is a good method to pressurise? exhaust?

At minimum, use muffler pressure. I doubt the carburetor is too big for muffler pressure to be inadequate.

is the fuel tank mounted under the engine ? or behind the engine ? if its under the chances are Fuel Draw which means the carby can,t draw and hold fuel in the lines . also is the seal between the carby and engine good ? is the front bearing seal good and not leaking ? the list can go on and on as many issues occur with old or worn engines. start with a richer needles valve setting and also add a pressure fitting from muffler to fuel tank breather. [ 3 turns out on the needles should get the engine running if its only the carby mixtures at fault.

Genius, just the job, Wow that is some power. Thank you very much :)

Thanks everyone. :)

Genius, Thanks very much. serious power there. s**t myself tbh still here though. What a rush!