1990 225 yamaha two dead cylinders???

davidkuehn5

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Joined
May 7, 2013
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6
225ETLD
i have a 1990 225hp yamaha v6, when i pull the spark plug wires off of the top two cylinders the engine doesnt change its sound so im assuming they are dead (powerless) cylinders. i have cleaned the carbs, replaced spark pluggs, hooked up fresh fuel, its getting spark to the plugs, they have good compressing 110 on each... what else could it be??
 

davidkuehn5

Cadet
Joined
May 7, 2013
Messages
6
Re: 1990 225 yamaha two dead cylinders???

i just bought the motor and dont know any of the history, it runs great when on the muffs but has little power when underload
 

99yam40

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Sep 7, 2008
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8,851
Re: 1990 225 yamaha two dead cylinders???

good compression and spark on all cylinders would leave you with a fuel/air ratio problem.
Carbs, reeds, or vacuum leak , but do not see vacuum leak on 2 cylinders very likely,
any way that would be my thoughts
 
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