I bought a CSR 305 for 500 bucks. Guy said the carbs needed cleaning. I could get it to run (barely) for a few seconds. Cleaned carbs, changed plugs, etc. etc. then I looked in the little window (for adjusting valves) and on the right cylinder, the exhaust valve opens and closes just fine, but the left one barely opens and closes -- it moves, just not much.
I'm thinking about whether I want to bother tearing it apart or parting it out, but I'm wondering what the possible causes of the valve problem might be. Parts are available and most are cheap, but the camshaft is not (almost worth the price i paid for the whole bike!) Nobody would confuse me for a mechanic, but I'm fairly brave.