been trying to figure out why my 150 hp yamaha shakes so bad with a heavy stainless prop. carbs have been gone through, sink & link done but still shakes at idle in gear. Have allways used non-eth. prem gas. seems like there is unburnd gas in water running at dock. plugs allways kind of wet also. Do you think that 87 oct fuel could help reduce prop rattle. Got manual for motor, compression ratio is 6.2 to 1 that seems low to me.
