I've recently punched out my 883 to 1200 (and I have had no head work done) ever since that time it will burn a quart of oil every 600 mi. there is no visible signs of smoke. It's had a compression test and the shop that has done the work said everything looked great. They also put it on the Dyno at aprox. 75-mph. under a load with no apparent smoke.
The bike has a force-winder air intake system with the breather tubes that enter the back of the KN filter and there is always a lot of blow back from the heads through the breather the air filter is always full of oil.
I've put 4000 mi. on the conversion with no change in oil consumption.
Any help on the cause would be greatly appreciated. Thanks Tim

 

Sounds like you pin-pointed the cause - excess venting from your heads. Time to check the venting system and fix it.

 

I would suggest finding out WHY you have excess venting from the heads, more like a ring problem than a venting problem. Find and fix the problem, not the symptoms. Do a leakdown test and then apply a small bit of oil to the cylinder and repeat it again and see if it changes to check the rings as the source of the problem.

 

Thanks for the info, if the compression test that was done showed good results wouldn't a leak-down test show the same?
What would cause the excess pressure in the head?