Hello All Just acquired a 1982 XT550. It´s darn near showroom condition and runs very well. When I first got it the oil was about 3 liters overfilled. I change oil and filter and put in what the owner´s manual suggested. Now all is good except when bike sits overnight oil drains to the sump and shows low on the dipstick. After running up to temp oil shows full on the dipstick. Where is the leaky check valve located and how much of a job to fix this. Thanks so much in advance.