The New Suzuki Quadracer HQ Welcomes All LT500 Quadzilla, LT250, LTR450, LTZ400, LTZ250, LT80 owners to the Suzuki Quadracer HQ forums
The "crud" looks like radiator sealer. I'd think its time to locate a new cylinder.
http://www.suzukiquadracerhq.com/index.php?action=store