Murray puffing smoke

[Stuckinmud15]

I just did some work on an inoperable murray lawn mower I had sitting in my garage and got it running very nicely, except the exhaust is a white/*almost* slightly bluish tint. I cleaned the carb, replaced the gasket and diaphragm, new spark plug, new oil. I let the mower run for awhile and the smoke will almost clear up, then come back, then almost clear up, then come back. Any ideas what this could be? Its a murray 4hp with the following stamped on it: model 10A902 type 2291 B1 code 00101155. Thanks!

 

[Stuckinmud15]

I just pulled the plug and there is oil on it and burnt oily buildup on the electrodes.

 

[mowertitan83]

could be a number of things from sitting so long the valve seats might not be seating all the way.