vibration on ’99 rude 15 hp 4strk

I purchased a used ’99 rude 15 hp 4 strk ls. I have it mounted on a ’99 Princecraft 178dlx deep v. I had it test run and compression checked and impeller replaced. Everything was good. Motor starts and runs great. When I Troll over 2 mph it seems to vibrate. At lower speeds and backtrolling it dosn’t. I’ve never had a 4strk before and wonder is this normal? Could it be caused by being mounted off center of the keel? The prop and skeg show no signs of previous damage or rebuilding. Could it be caused by turbulence of deep v and main motor? Any replies would be appreciated.

Mwal

What kind of shape is the prop in and have you checked to make sure you don’t have a bent prop. Does this get worse if you are going faster?
jc

The prop shaft could also be slightly bent. Take off the prop, put it in neutral and see if the prop shaft “wobbles” or “swings” as you turn it. It’d be nice if you knew someone that had a dial indicator to check it with. If that shaft is bent the vibration will be in direct relation to the severity of the bend. Thus it may not show up till you give it a few RPM. In other words, the more the bend the sooner In speed you will feel the boat and motor shake.

YEs the vibrations gets worse as you increase rpm’s
I will also remove prop and check shaft. Thanks for the ideas.
MWAL

i have a similar problem with my 2001 merc 15 hors 4 stroke, i have a new prop on the way i have been told that this should take care of it, but my prop has been beat to shnikes literally looks like somebody threw it in a big blender. i will let you know if this works my prop will be at my house tomorrow.