Shaft Size

[fotoguy]

New to forum, can someone tell me how I can determine the shaft size of my 2012 FourStroke 25hp. I am having trouble with palpitations on my Mako at 4500 rpm's. Mercury can not fine the problem. I think the shaft is to long, and may need to add a jack plate. Advice please...

 

[galamb]

Try this...

 

[Fun Times]

Can someone tell me how I can determine the shaft size of my 2012 FourStroke 25hp.

Also do you have your engine serial number handy? Sometimes it will say what the shaft length was when built new when looked up by a Merc dealer.