RE: MVVS 45IRS/MG
Angelo,
The rated power of this engine is stated with the #3204 canister silencer, which will give you a noticeable RPM improvement, over your current Bisson muffler.
The Walbro carburettor on this engine is equipped with its own internal fuel pump.
The pump nipple is the one, which is closest to and needs to be connected to the nipple on the crankcase.
The pump operates irrespective of the choke position and it should be is enough, to rock the prop back and forth, in a wide arc (no flipping), to bring fuel into the carburettor.
Make sure this happens on your engine.
After fuel reaches the carburettor, the engine is capable of starting within just a couple of flips.