Yes there could potentially be air leaks since it won't start but no reason to suspect that using all new gaskets.
The head is the type with the groove for the O ring, I used the regular 50v gasket because I didn't have an O ring.
I used an av89 cylinder because what I gather they have better porting and are a faster cylinder than the stock 50v cylinders. The head and cylinder are brand new MBK. If the O ring is a problem I will order one, seemed fine to use the other gasket but I could have missed something.
Any help or ideas is appreciated. Could be jetting, I am waiting for jets from treats, the clone I was using took standard size 5mm jets, the new one I have takes 6mm jets I hope.