A lot of RSV riders use Seafoam.
There are a few who use harsher chemicals, but I've found Seafaom to usually help. Start with a heavy dose. run the engine for a few minutes to get the Seafoam in the carbs, then let it sit overnight. Then take the bike out and run it. Also make sure you're keeping the revs up on the engine, the RSV doesn't lug at low rpm's like most vtwins do.
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