Yamaha low idle lower unit issue

NEFisherman

Recruit
Joined
Mar 23, 2018
Messages
5
Hey everyone new to the forums, not new to boats. I am posting in regards to a 1994 yamaha 200hp 2-stroke. Just looking for a little advice or help. I am currently getting the motor ready for the season, and had some issues last year with low idle. Motor has great compression and carbs were rebuilt as well as a new fuel system. When the boat is at low idle/power I am getting a clunking type noise, not fuel carb but more so lower unit. When I raise the rpms and the noise disappears and the boat is on its way with no problem. Before I go ahead and consider purchasing a new lower unit could it be an easy fix, I am running a SS prop.
 

robert graham

Admiral
Joined
Apr 16, 2009
Messages
6,908
Maybe some lower unit gear lash or prop rattle at low idle....you could drain/check lower unit oil but otherwise I wouldn't worry about it.....
 

scoflaw

Ensign
Joined
Jun 2, 2010
Messages
962
More than likely prop rattle, normal with a solid style prop hub. You can check it with the prop off to see if the noise is gone.
I switched over to a rubber hub style, that noise was driving me crazy.
 

NEFisherman

Recruit
Joined
Mar 23, 2018
Messages
5
I will definitely take a look, basically that rubber style hub is like a dampener to reduce the vibration I am assuming, yea I can't stand the noise. Lower unit oil looks fine. Do I need to buy a new prop with the rubber hub, or can I purchase the hub separately
 

scoflaw

Ensign
Joined
Jun 2, 2010
Messages
962
It's been said that different solid hubs will quiet it down, I had no luck after trying a couple Flo-torcs. You are going to need a new prop if you want rubber. I'm happy with the old style Mirage. Good opportunity to fine tune what pitch your looking for as well.
 

scoflaw

Ensign
Joined
Jun 2, 2010
Messages
962
Not a prop guru, but you haven't mentioned what prop you have, or any of the specs that help with making a prop decision. We were talking prop rattle.
 

NEFisherman

Recruit
Joined
Mar 23, 2018
Messages
5
I have run it in the water usually hear it leaving the dock at low rpms, or coming in... we are talking at 400-500rpm
 
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