hi whats the best oil to put in a 250 mono, as i've been out today for the first time on it and the cluch seems to drag , it might be the clutch that as gone but just want to make sure its not the oil first. also it does not rev out right , it goes all rough afer about half revs i tryed changing the mixer screw with not alot of joy, i also tuck the air filter out and tryed it again with no joy (put it back). is there a stiffer spring you can get to fit the sandard shock. please help