I have a 2002 yz250 and when I change the oil I pull off filler cap and drain oil but no matter how hard I try I only get about 300ml out. What the heck? I can pull the weep bolt also. When I fill it up it only takes 300ml also till it comes out the weep hole. The case itself says 750ml will somebody with the same bike help me out, is that all the oil I will get out or is there a trick to it? Also is there a filter to change also or not I can't find one.