I have a 2007, 80hp 912UL with 270hrs TT. It is extremely difficult to start when cold. Carbs have been completely rebuilt and synced. New plugs, new fuel pump, new battery, 91 octane auto fuel, assembly of enrichner choke verified as correct, excellent compression, fuel in carb bowl ~ 1/4" below rim before initial cold start. High wing gravity feed to fuel pump. Fuel pump is pumping fuel. All grounds and connections removed and cleaned around ignition modules, engine and firewall. Check plugs after several cranks and no do not appear wet. Engine will slow to 1560RPM when holding throttle back. Chokes are pulling to the full on position.
If and when the engine does start it hits and runs perfectly. It is like I forgot to turn the ignition switches on. Once running, restarts the same day are on first crank. Ambient Temperature during start has been 80F to 100F.
I am at my wits end trying to figure this problem out. Any suggestions would be very much appreciated.