I have been running my bike quite a bit in the 65-75 range lately, and I have noticed that the bike has started using oil. (In the last approximately 2000 miles, I have had to add about a half a quart.)  There is no oil on the ground, and no blue smoke coming from the tail pipe that I can see.  More importantly, my mileage has not gone down significantly.  I am 300 pounds, and usually get 50-55 mpg. (Serowbot tells me that he regularly gets 60, but I am twice his size, so I am happy.)  Lately, it has been closer to 50 than 55.

My question is this, "Is this normal oil consumption for an air cooled single running in this speed range?"  I am especially interested in hearing from those of you who regularly commute at the 65-75 speed range.

Thanks.

Mine leaks a bit at the clutch arm thru the case, but not bad. So, I am always losing some, But, it starts using oil once I get around 2,000 miles or so on it. Change oil & it slows considerably.

my 06 uses more at highway speeds than round town, never more than half a quart between oil changes..13k on the od