Mercury 25 HP bigfoot vibrating

[fishook76]

I purchased a used 2005 Mercury 25hp 4 stroke Bigfoot with controls, power T&T. Put it on my pontoon and noticed a significant vibration. This happens when it is in neutral, and when in gear and driving. I will add that when I purchased the motor I laid it down on its side and cannot remember which side- for about an hour. I did not notice oil leaking out but did notice a small amount - very minimal, in the intake. I know the motor was serviced just before winter storage the season before I bought it. The oil level was above the fill line…But it was very clean/new. Motor seems to run and start just fine; just a lot of vibration. After reading some posts some say to check/adjust the air mixture screw on the carb, use some seafoam, put rubber mat in-between the transom and motor...any help would be appreciated from someone who has had this issue.
Thank you

 

[bchaney]

Did you test it before you bought it? If so, was it vibrating then? You could ask the previous owner or the shop that did the recent service.

You may want to post this in the Mercury OB forum.

 

[southkogs]

You may want to post this in the Mercury OB forum.

Moved it for ya'.

 

[fishook76]

I was able to talk to the previous owner and they did not have any vibration issues. No issues from the shop either. I have a outboard mechanic friend come over and he said it was the "tuning fork" affect. meaning my combination 4 stroke carbed 25hp on my tooner was a perfect combination for a vibration. really, nothing to do about it. Thoughts?
Also, I'm new to posing on forums and not sure how to see the new thread in the Merc OB forums???...