burning oil?

i have this '08 FE450 that i bought about 3 months ago from a reputable dealer who,although he didn't have the reciept to show me assured me it had had a complete engine overhaul to the value of £1200,it runs really sweet,I decided to track down the previous owner who was very helpful and confirmed that the work had been done.It has about 621 hours on the clock.I changed the oil and put a litre in at 607 hours ,went for a days riding in wales(5 hours added on the clock),a bit of greenlaning and 2 day fast-ish rally(70mph) at times in Yorkshire at the end of day one the oil needed about 200mls to top it up,did second day and changed the oil at 621 hours and measured how much came out 800mls so in 14 hours its used 400mls of oil,it doesn't smoke at all even from cold and my riding buddies say they can't smell burn oil when behind me,is this an expected amount to consume? what do you think