It is possible that an overly tight cam chain tensioner is putting too much drag on the engine. It's also really, really easy to rule this out: Warm up the engine. Loosen the locknut. Screw the bolt in with your fingers until you feel increasing resistance then back it off one flat of the hex and lock it in place. It's also possible to do this with the engine running so that you can see the effect. Never tighten the tensioning bolt with a wrench - only your fingers - you will overtighten it guaranteed if you use a wrench.
If that's not it, the traditional cause of a hard start when hot is a too-rich condition. Fuel injected engines can do this just as much as carbureted engines can. (Dribbling injector, bad coolant or intake air temperature sensor, engine modifications that aren't properly accounted for in the fuel injection calibration, etc.)