Mario those are bits I had yet to wipe off from when I cleaned the carbon off the piston tops. No scratches at all. When I stripped my lovingly maintained 2 stoke Yamaha 115hp outboard it has discoloured bores. It does very little idling just to warm up then it runs flat-out...no trolling. I have seen some bore discoloration in a d1. You may be right but I'm not too worried. It used about the same amount of oil as my 4.0 did when it was run in and doesn't blow any obvious smoke out the back when cold and when running hard...I have had plenty of people on convoy behind me over the last.few years. Heaps of power. I reckon it's fine but I won't be pulling it out any time soon. Cheers
Ps Mario this motor has been on petrol only for 99 per cent of its life. Only nice clean LPG for a very short time initially when I got it.

