This is still a subject dear to my heart, or pocket book. I still have problems with oil burning, but it never smokes and I am getting about 250 to 350 miles to a quart depending on riding conditions. It is the best it has ever been though. So, I am going to tear it apart again of course! I have the .090 restrictor in the pinion shaft, as the aftermarket shafts for Sportsters come with one, but they don't tell you to put it in, as there are no instructions.... see: viewtopic.php?f=19&t=10915&p=83577&hilit=.090#p83577
This modification has led to the least amount of smoking and oil consumption ever! It is not to my satisfactions though! I want it to run like a "raped ape", as it did when I first put it together the last time with correct KH/K pistons and Hastings rings. The main problem is too much oil getting in the bottom of the crank case! I am running a '72 series pump, so I am and it works well pressure wise, but with the ristrictor and no place for built up pressure to go, it is just forceing more oil than needed into the bottom end. There was a lot more places to oil on a Sportster like the top end.
I thought about putting in a small spring loaded pressure relief valve in the timing area case in the oil passage between the outside timing cover and the main case at the top, where it goes to feed the cylinder oiler's, that I plugged up earlier in the course of things with JB Weld... a relive valve here would take down the not needed pressure supplied by the larger '72 oil pump, but since the bloody thing is leaking from the pump anyway, and I have to pull the pump, which means pulling the engine, I figure I will go back to the original pump from '55 that has an oil relief valve in the pump! My cases being '55 are already set up for it, and I just have to find a good pump breather tower with the hole that matches up, or drill one! I bought another similar pump on Ebay for $60 bucks that had the spring and the check valve in it, that I had given away from my original one that was all messed up anyway. I am still collecting parts to tear it apart, but the single best thing I did to get rid of oil burning, and bad ring seating was to restrict the hole in the pinion shaft to .090, or 90 thousandths if that is correct??? I sent a set of KHK cams to the grinder yesterday too! Can't wait to have a ripping machine!