My port engine has much more white smoke than my starboard engine. Runs alittle hotter than starboard and the water temps will jump up as high as 200 sometimes then quickly come back to 160 and steady. It will do this while idling (after warmed up) and at higher RPM's. It also sounds like marbles or clicking in the riser. Not sure if that's a normal sounds. 550 Hours on both engines. Raw water cooled. Was in fresh water for first 300 hours of her life. Now in salt water. Have noticed some loss in RPM's and boucning of RPM's every once in a while.