Yamaha stumbles at high rpm

[Virginian]

I have a Sea Hunt with a 2005 Yamaha 225
Motor has been bulletproof for years. This spring motor idled rough and would stumble onto plane. Replaced fuel, fuel / water seperator,ball, initial fuel filter were line enters motor. Ran 50/50 mix sea foam to fuel mix through motor.
Currently the motor idles well and runs well except if run over 5000 rpm. High rpm reveals a surging feeling almost like engine is starving for fuel. Ran boat for 1 hour up and down river at 3200 to 3600 rpm with no issues. Increase rpm into higher range and “stumble” shows itself.

 

[99yam40]

is this a F225?
full motor I D helps others know what motor you are dealing with.
and I never heard of running a 50/50 mix of seafoam before

 

[Virginian]

Clarify
1 gallon of gas with 1 gallon of seafoam in a seperate tank with gas line running from it. Idle through 3000 rpm for 10 minutes. Rest for 20. Repeat until all fuel is gone

 

[99yam40]

seafoam shock treatment should be 1 pint of seafoam to 1 gallon of gas.


there are a lot better fuel treatments available to help clean fuel systems and 2 stroke motors
and you still have not given a motor ID so we still have no idea what motor you have

 

[Virginian]

Four stroke 225 2005
I know that seafoam can be used in conentrations up to 50/50. The motor did not smoke much and ran and idled better after treatment. I think using a can in a gallon of gas was probably more in line with recommendations