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Message board > Engines > Yamaha 50hp outboard grey smoke,why?

Message 3 of 3
Posted by member Kelvin on Monday 30 July 2012

Hello Barry, Is the engine a two stroke or four stroke? If its a two stroke there seems to be a problem with the air/fuel/oil ratio. If there is too much oil in the mixture there will be a lot of white/grey smoke. Check this out first. Most modern 50hp engines are four stroke so I guess its likely to be one of these. In this case make sure you are not mixing two stroke oil in with the fuel.....sounds obvious but it happens. If its not the case there are two primary possibilities. One, the piston rings are shot and are allowing oil from the sump up into the combustion chamber. Two, the fuel/air mixture control is out of balance allowing too much fuel into the cylinders and the white smoke is the product of incomplete combustion. Best thing to do is have the engine checked over by a yamaha service centre. kind regards Kelvin

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Message 2 of 3
Posted by member Barry Dean on Monday 16 July 2012

Its not grey its white smoke.

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Message 1 of 3
Posted by member Barry Dean on Tuesday 10 July 2012

Just bought a Hardy Family Pilot and the Yamaha 50hp engine that came with it sends out greyish smoke all the time.when i first got it i filled up the 5 gallom tank there was already 2 gallons in it,how long it had been it there i don't know but i think it could have been several months,then i put in quite a lot of fuel additive to flush it through,should it keep on smoking or is it old fuel originally in there.Or could it be something more sinister.It starts ok and sounds ok and is not noisy,help.

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