After a WOT run, I hear a faint knock/rattle when shutting down (backing off the throttle to stop the boat). Only on the "backdown" is when I hear this. Timing a tad high? OR???97 Yamaha 150 V-max with lots of hydro-tech parts running super unleaded. 70-72 size jets, 175psi compression, Timing around 24 degrees.
is this oil injected,i thought it getting a gulp of air when let off quick try timing or jetting to lean,1 run 50-1 in none oil injected 100-1 injected the oil act's like lead giving it longer burn rate for the alcohol base gas o klenser i use with ethanol gas i used last summer
Before getting too carried away, check the prop to make sure its tight. Noise as the prop moves back & forth on the prop shaft can radiate to the power head making one think its an engine problem.
Prop is tight. Gatorred, you're killin me here...It is oil injected. Never noticed this before, and haven't since, but, I've not shut it down that fast since then either. Backed of timing about a screw turn also (just in case). Probably wasn't enough, but, made me feel better.Ray, any ideas?
Shutting down too quick will also temporarily lean the motor, as well as making a prop ratchet as Rodbolt stated. We have added a washdown or primer circuit on the race motors to activate when they have to shut down to keep from siezing the motor. Those jets should be rich enough for the parts you have added for normal operation. Most of the time, the air box has been removed from the HP motors and it will tend to amplify any noises form the reeds and carbs. Best advice is not to shut it down that quick.
I've not noticed it since. Now aware of it though, and haven't shut it down as quick any more either. Thanks for the help. I'm sure I'll need more more more help soon...lol.
yamaha V-max shut down knocking?
Timing a tad high? OR???
Linear Mode
