johnson 1985 20hp and 25hp carb difference

[Newyota]

Can anyone tell me by looking at carb how I know one from the other.Should the venturi/throat be bigger like on my 9.9hp to 15hp canversion or is it just the jetting?thanks

 

[jimmbo]

It won't be just the jetting.

 

[boobie]

Venturi size different.

 

[Newyota]

Thanks-Had someone get back to me and looked things up and found that just the intake hole size is different.The same carbs are used on both 20-25, 20 just restricted by the intake and main jet the same.

 

[jimmbo]

When I cross referenced the parts list, it showed the intake having the same part# on both engines. Carbs were different and were jetted different

 

[Willyclay]

There might be some useful info in this old thread at the link below. Let us know what you do and how well it works. Good luck!

http://forums.iboats.com/forum/engi...ds/281518-converting-a-20-hp-johnson-to-35-hp