I Just Found Out Something About My 4 Stroke Yamaha . I Have Had It For Awhile And When I Got It 2 Years Ago It Had No Smoking Or Power Or Problems......So I Began Using Castrol Full Synthtic 10w-30 Synyhetic Oil And Prolong Oil Additive In The Crankcase... This Was A No-No. The Smoking Got Very Bad,, And The Engine Lost Power, Starting Was Getting Worse. So I Took It To A Boat Motor Genius I Found Last Week, (Not A Dealership). The First Thing He Asked Me Was What Kind Of Oil I Was Putting Into The Crankcase. I Told Him And He Said Dont Do That. The Synthtic Oil And The Prolong Additive Were To Slick For These Low Compression Engines (2002 Yamaha 4 Stroke 6 Hp.). The Contents Of The Crankcase Was Slipping Past The Cylinder And Rings on every stroke And Burning In The Combusting Chamber And Fouling The Plugs So Bad It Was Causing The Starting Problems, Loss of power and it was using oil like crazy (carbon Build-up). He Sprayed A Carbon Remover Through The Carb. For 5 Minutes Running At 5000 Rpm's And Cleaned It Out. I Drained The Oil, Put Plane 10w-40 In It And That Was All. The Motor Does Great Now...........I Hope This Helps Someone With 4 Strokes
I am having the same issues with my 40, I am still trying to figure out whats fouling my plugs all the time. Maybe it could be the oil that am using, Ill have to try using Yamalube that the motor recommends see if that helps.
I am having the same issues with my 40, I am still trying to figure out whats fouling my plugs all the time. Maybe it could be the oil that am using, Ill have to try using Yamalube that the motor recommends see if that helps.
THE GUY WHO FOUND MY PROBLEM IS AN ABSOLUTE GENIUS WHEN IT COMES TO BOAT MOTORS.....I STOPPED PUTTING IN SYNTHETIC CASTROL AND STOPPED PUTTING IN PROLONG ENGINE ADDITIVE. I DRAINED ALL THAT OUT OF THE CRANKCASE AND PUT IN PLANE CASTROL 10W-40. THIS WAS AFTER HE CLEANED OUT MY CYLINDERS, CLEANED THE OIL OFF THE PLUGS, AND CLEANED THE VALVES. HE DONE THIS BY SPRAYING A CARBON REMOVING SPRAY INTO THE CARB. FOR 5 MINUTES WITH THE ENGINE RUNNING AT 5000 RPM'S, THEN LETTING IT SAOKE AND REPEATING THE PROCESS ONE MORE TIME. NOW THERE IS NO SMOKE, NO LOSS OF POWER AND IT WILL START WITH 1 OR 2 PULLS. THE PROLONG AND SYNTHETIC OIL WAS TO SLICK FOR OUTBOARDS AND JUST PASSES BETWEEN THE CYLINDER AND RINGS AND FOULS UP EVERYTHING IN THE COMBUSTION CHAMBER WHEN THE PROLONG AND OIL WAS BURNING WITH THE GAS. MY PLUGS WERE SO OILY IT WOULD JUST DIE WHEN RUNNING AND IT MADE IT ALMOST IMPOSSIBLE TO CRANK.