1987 85HP 1990 90HP SAME POWER HEAD?

[Long Island Boater]

Hello, I have a 87 85hp with a bad lower unit, and a 90's force 90hp with a blown power head, I know the lower units are different and the electrical..... but can i use the 87 powerhead on the 90's 90hp Force?

 

[Nordin]

Yes you can.
The bolt pattern is the same and the drivshaft will fit in the crank.

 

[jerryjerry05]

Try the lower unit swap.
.​I'm not sure it won't fit.
Give it a try and post the results???

Are the shafts the same length? they come in 20 and 25"

 

[Nordin]

If you have had the 90Hp at your boat and you swap the powerhead for a 85Hp it will fit. The powerhead will fit anyway because the bolt pattern is the same.
As jerry says, are the shaft length the same of both? If they are, no problem.

The gearratio can be or will be different.
If the 90Hp is the one with 2 piece drivshaft the ratio is 2:1 or 1.93:1 I think.
The 1 piece gearcase as for the 85Hp, had 1.73: or 1.93:1 I think.

About the ratio I am not 100%, but there were a couple of different typs.

 

[SkiDad]

if the 90 is 1990-1994 it should work - for 1995-1999 i think it might be iffy. It's a lot easier to swap the lower unit if you can find one on craigslist.