ok to start off i just got an rm 250 and its in moderate condition. i used to have a 2003 yz 85 so i learned a little bit how to work on it from that. but this bike is older and i dont have the repair manual yet. first off the exhaust is pro circuit and i dont think its 100% machine spec. it is very loud when it warms up much louder than it should be. also smoke is heavy and comes out the exhaust manifold. my friend says i am missing something but we dont exactly know what. i can move the pipe around and it doesn't really look like it is being held on at the manifold, like i think i should be. TO the next problem my rear back brake is either leaking brake fluid or letting in air. i bled it thoroughly filled the fluid and capped off the resovoir and tightened down the bleeder. so than i was just pushing down the brake with my hand and i heard air being sucked in and i saw brake fluid leaking.. my friend said it was the line that it wasn't tightened down. but i checked it and it was very tight. so i listen more closely and it sounds like its coming from the resovoir but im not sure. so any help on that would be good. and one last thing the crank case cover has a crack in it and i think its causing it to leak transmission oil. other than me having to fill it with transmission fluid all the time is there any problems it will cause, if i don't get a new one right away? so any help you could give on any one of these matters would be greatly appreciated!!