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Usually this means blow by. You may need to do a leak down test to see if the rings are ok. When it is running, if you open the oil fill cap, does it smoke out of the crankcase? Hard to imagine a whole liter of oil coming out on one ride. Pull off the crankcase hose going into the crankcase also and see if there is smoke. What year and how many miles? Look for the VIN number and year on the frame near the top and front of the bike. (under steering lock on left side)