Greetings,
I've found myself caring for my parent's 20' pontoon with a Yamaha 75 2 stroke. It ran fine last year; I've put 4 hours on it this season and it's not getting up to full power. 3900 or so RPM's and 15 knots when the norm has been around 5200 and 21 knots. I fly jets for a living, not a piston guy let alone knowledgeable about marine engines but I checked the plugs... they seem ok. The fuel filter was clean, super clean. Engine only has 122 hours on it. My gut is that it is something simple... shop can't get out there for three weeks but said to change the plugs anyhow. Looking for anything I can do/check that is reasonable, keeping in mind I know nuthin'.
It's the C75T - I mix the oil/gas at 1:50... used a fresh tank of non-ethanol 89 octane.
I've found myself caring for my parent's 20' pontoon with a Yamaha 75 2 stroke. It ran fine last year; I've put 4 hours on it this season and it's not getting up to full power. 3900 or so RPM's and 15 knots when the norm has been around 5200 and 21 knots. I fly jets for a living, not a piston guy let alone knowledgeable about marine engines but I checked the plugs... they seem ok. The fuel filter was clean, super clean. Engine only has 122 hours on it. My gut is that it is something simple... shop can't get out there for three weeks but said to change the plugs anyhow. Looking for anything I can do/check that is reasonable, keeping in mind I know nuthin'.
It's the C75T - I mix the oil/gas at 1:50... used a fresh tank of non-ethanol 89 octane.
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