Yamaha F25 problem

Sarrre

Cadet
Joined
Jul 31, 2015
Messages
28
Hello guys, I got a very strange problem on a Yamaha F25. It has not been in use for a few years and I don't have any history of it.
The problem is that it doesn't has any power when exceeding about half throttle. It shakes a lot when exceeding half way of the throttle. Just like it is entering a rev limit mode. I have checked compression (174 psi on both cylinders) and changed spark plugs (they were black).
And the funny part of all this is that it doesn't matter which way I swap the spark plug wires. It runs well at low rpms and runs crap at high rpms no matter which way I connect the spark plug wires. Is it really supposed to be like that??
 

racerone

Supreme Mariner
Joined
Dec 28, 2013
Messages
36,032
On a 2 cylinder 4 stroke both plugs fire at the same time.-----So yes that is very normal !
 

racerone

Supreme Mariner
Joined
Dec 28, 2013
Messages
36,032
?----What was the outcome / final result of your trouble shooting ?----What was wrong with the motor ?
 

giannisp

Recruit
Joined
Oct 22, 2022
Messages
1
hello Sarrre! did you finally find a solution to the problem?? I have the exact same problem on the same machine!!
 
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