Syk

Syk is the street name of a forbidden circuit booster, presumably the Cybertronic equivalent of an illicit narcotic. Syk is forbidden even among the Decepticons.

Syk's effects (and negative side-effects) are unknown, but it may be similar to overclocking, where the increased strain on the boosted system carries a risk of burnout. Alternately (given its dealers), it may be chemical in nature.

Fiction

Earthforce

While Soundwave searched for traitors by scanning the surface minds of his fellow Decepticons, he was surprised to learn that Mixmaster was still trading Syk on the base. Soundwave filed this fact for future blackmailing purposes.

Scrapper had Mixmaster pinned to a wall, telling a story about his brother, when Soundwave detected his thoughts. Presumably, this story was extremely boring, causing Mixmaster to wish fervently he was high right then.

Stupid Scrapper. Secrets

TransTech

Stungun rattled off Syk as one of several controlled substances Jackpot might have been on besides Nucleon. Jackpot was unamused at the accusation. Gone Too Far

Animated

Beachcomber was known to use various controlled substances, including Syk. Bumper considered Carrera's sports announcer aspiration to be a "Syk-dream" due to his speech impediment. The AllSpark Almanac II

IDW Generation 1 comics

Springarm and Wheelarch, two police officers in Rodion before the war, expected to find some Syk dealers to arrest during a day-long patrol in the Dead End. They didn't, as Orion Pax had already arrested all the criminals himself. Chaos Theory #2