Engine/carburetor problem

Air leak or ignition connection engine was stuttering
But it's not simple after opening the throttle immediately drops to 4600 and gets stuck there

No
After treatment one flight was fine and a second flight the problem appeared

No
After treatment one flight was fine and a second flight the problem appeared

Hello Beny

OK so we know it worked before, now we have to find what changed.  At your 100 hour did they remove the carburetors and check the floats?  The float pair, 2, should only weigh 7 grams.  It is unlikely to be ignition as you have 2 of those and it continues to run.  Can you tell us the conditions you are flying in and fuel used? Have you checked the carburetor synchronization?  Perhaps something slipped in the linkage.  As someone said earlier check your fuel tank venting.  If it is obstructed it would run well for a short time but once a vacuum in the tank starts it will not pump fuel correctly.  You can eliminate this idea if it occurs on the ground by just opening the fuel tank cap for a run to see if there is a difference.  Dont fly with the cap removed. 

Only thing I can think of at the moment. 

Cheers