took the ski out today for the first time in 2 yrs. did not want to rev past half throttle and didnt seem to have much power (would bog down under heavy load/full throttle/not much pull ect) idled good started good. thought maybe just needed to be run a bit so kept her out for about an hr or so. pulled the plugs, one was black/brown but half of the other was white. started it after i removed it from the water and now seem to be getting a raddlling noise from the motor. fresh gas/oil compression was good before i went out. could i have hurt the motor? also can you do a topend rebuild on these with the motor still in the ski?