Re: 36 tooth sprocket on a chinagirl ????
You won't be over-revving the engine with a smaller sprocket. The inverse will happen actually. You'll end up going faster for the same revs. A 36t sprocket may be a little too tall of a gear for a stock 66cc engine, but it should handle it just fine if you pedal the bike a little faster before engaging the clutch.
About 4 links need to be taken out to take up the slack.