2 stroke Yamaha 150 2003 Z150TXRZ knocking on de acceleration

[Scout 234]

Troops, I have a 2003 2 stroke Yamaha 150 model z150TXRZ. It has about 500 hours and I noticed a loud knocking /rattle sound when I back off the throttle to come off plane. It went a away when I I gave it more gas and it idles okay. Any help is much appreciated !

 

[Fishandboat]

It's not the prop spinning is it

 

[Scout 234]

Thanks for the response, I don't think it's the prop... it's a bit of frightening expensive type of sound. Almost like a motor running without oil; very metallic sounding. It ran fine all day and I only heard it for a second before I gave it more throttle and it went away. I backed off to a little more than idle (no wake zone) and went on to the dock no problem. No noise during flush out at home?

 

[racerone]

At home.----Put motor in forward gear.--------Now turn prop clockwise.-----What do you hear ?----Now try and turn the prop counterclock wise.---------My bet is that it is the prop that you hear on rapid slowdown !!!