I need some techical advice from you gurus. I have a yzf 450 04 model. Went for a ride on the weekend and 10 min into it I had picked up long stringy tree bark that had wrapped itself around to the width of the front sproket to the point it was compressed solid. It had done the same to the rear sproket. Have never seen anything like it. Took me 45min to rip it all out before continuing the ride. Mind you I still have the front plastic gaurd on for the front sproket which would not have helped. Got going again and continued for about 32k's. Bike was not running 100%. The power was lacking it's usual bark. So decide to pull over after 32k's and change the spark plug. We were at altitude and riding in the snow so this could have been part of the reason. Thin air etc. After taking about 30min to change the spark plug (it needed replacing by the looks of it) I tried to fire her up. Almost fired up 1st and second kick. 3 - 20 kicks later nothing. Checked bike over and soon realised the bike had been leaking oil from what I could gather from the front sprocket area. There was so much mud on the bike it was hard to be certain but I am 99% sure it is from this area. I checked the oil dip stick and no oil reading! @^!%@ Mind you the bike was stationary for 30 mins and to get a reading you are meant to have the engine running for 3 min. Was highly concerned about how much oil I had lost so did not take the risk and got my mate to tow me back. Cut a long story short....I have cleaned up the bike....dumped the oil and could not be happier to see oil come out. Checked the oil filter and it was as if it was brand new. No fragments in it. I measured how much oil I had drained out of the cold bike (did not pre warm it up as usual before dumping oil). I had 750ml left. The bike takes 1200ml total. So I had lost 450ml. Questions: With just over half the amount of reccommended oil in the bike would I have done any damage internally? Do I have to split the engine to change the counter shaft seal? My main concern is any internal damage with the amount of oil I had left....or was that still enough, and I am concerned about nothing? I will determine the exact point of leak once I get a chance to fill her back up with oil and take for a quick spin to anaylise exactly where the leak is, now that I can see with all the mud removed. Appreciate any advice.