Well, do a leakdown on the motor.. Fueling still using a separate piece for the sump pickup part of the oil pump? Maybe a damaged piston oiler? LIfters? Some lifters push too much oil to the top end. That will cause the bleed.

 

Gonna tear down soon here.

 

another thing to test would be your oil pressure, maybe the piston is bound up in the cam plate or the bore has something up with it?
m

 

Good point.. Relief valve would have to be stuck closed. Does the oil filter look fat?

I was thinking that maybe the metering hole for the crank was too large since it has a new plate.. Too much oil to the rod and it tosses oil everywhere..

 

Considered that as well but, like Max said, the piston would have to be stuck in the close position and I keep going back to the 1200 miles with no issue. I suppose something could be going on that might trash up the piston bore causing it to stick; dunno. The 1200 miles with no issue would indicate that something changed/happened to cause the blowby; just don't know what it might be and it seems the OP has checked the box on most of the possibilities.

EDIT: OP should do a leak down before tear down.

 

Oil pressure is great .

 

Oil filter is fine even tried different couple .

 

i agree, leakdown. Also, does the engine have a noticable knock at light throttle changes, like when you throttle blip at idle?

ive popped a number of Harleys after an engine conversion to forged pistons from bad tunes (ignition and fuel) and when a piston swells from excessive heat it still makes decent cranking compression but knocks at light throttle changes and blows a shitload more oil vapor out the breather.

most times people blame the machining but its more often the fuel or ignition timing that caused the overheating than anything. add 11 CI to a motor and it needs more fuel, and usually higher CR pistons come with which requires an altered ignition timing.