Black soot on crank. Opinions anyone??

I have just torn down my old DT 250 to replace the rod,(which I'll send to EG) and noticed the crank and bearing is coated with a black gummy soot. It has about 20 hrs. on new top end. Would like to hear opinions about jetting etc.

Thanks, Jim

I have been using YamaLube 2s. This bike still has oil injection hooked up. I can't say about filter maintanence before the last two years, but I change/clean the filter after every ride or two depends on the conditions.
I use no toil. I even do the grease ends thing.

Hummm??? Well, thanks for the input.

Jim

Jaybird,

The last ring and piston show a small amount of discoloration about 3/4" below the ring. This whole top end only had 20 hours on it. Had it bored by EG. It (the gunk)probably came from the previous piston & ring which I don't know how much time they had on them. From the difference between power before and after it must have be quite a lot. I didn't notice any rattle noises from ring or piston. I just have the knock on a freewheel deceleration that I think is the rod. I can feel no noticeable up and down movement from the lower end of the rod but the top end seems to be loose. When I did the top end this spring I replaced the top rod bearing with the piston. I am assuming the top is worn enough to cause the knock.

Thanks for your input,
JIM