.I have a 1984 Yamaha 115 hp V4 that i recently got running again after several years. I went thru the carbs and cleaned them and all fuel delivery components check out. The motor runs but roughly and does not like to idle though it will at times with sputs and sputters. The spark plugs all fire as they should and vacuum lines seem fine. The only thing i can think of is maybe the timing is off. I was not around the motor ran so I do not know its condition before I got it. Any ideas?

Tyler Johnson, PSL Florida, October 2009

The cause of rough running is the folowing:1.incorrect timing 2.throttle linkage adjustment 3.carb adjustment 4.adjust spark plug gap to correct setting 5.clean fuel, water free. my first check would be number one on the list.also it depends how long the motor was used, this would be worn out connecting rod bearings and crank. i hope the no. 1 correct the problem.

shadow_08, February 2011