I have an 07' yz450 where I am continually having an issue where oil keeps seeping out between the oil cover and crank case. It is seeping out at a pretty alarming rate. I have wasted about $30 already on oil and way to much time trying to see if I have fixed the leak. Here is what I have done so far:
1) Replaced all 4 o-ring gaskets which include the three small o-rings and the larger o-ring. I had noticed one of the three small ones was in pretty bad shape but just as a precaution replaced all of them.
2) Ensured the o-rings are in in place (done this several times). For the small o-rings I put them on the bolts just after I put them through the cover to ensure they don't fall out. The third is definitely in the right spots when I put the cover on.
3) Tightened all 3 bolts down to spec.
There are no abrasions or cracks anywhere a long the case where the oil cover adheres to. I have done this numerous times in the past but noticed this problem just started popping up. The only conclusion I can come to is the oil cover may be warped. As this seemed to coincide with taking it to St. Anthony sand dunes where it was running super hot.