Changing outboard 1978 85HP to 1988 88 HP

[bcomer]

Hello,

I am looking at replacing the 1978 85 HP Evirude on my boat with a 1988 Evinrude 88SPL. My questions are:

1. Will the throttle and shift cables used on my 85 work on the newer 88?

2. Will the wiring harness on my 1978 85 HP work for the newer 88 SPL?

3. It appears the gear ratios are different 2.29:1 on old 85 and 2.0:1 on newer 88SPL. Can I use prop from my older 85 on the newer 88SPL? The prop on 88 SPL is shot.

4. Is there anything else I should be considering with such a change?

Thanks - any and all help is appreciated.

 

[Dhadley]

Re: Changing outboard 1978 85HP to 1988 88 HP

1- Yes.
2- Yes.
3- Yes.
4- Yes. We'll assume you had trim on the 78 so your trim switch will be fine. If you didn't have trim you'll need a switch. Consider a water pressure gauge and a tach if you don't have one. The gearcase alone is a much better (sleeker) design so you'll probably be able to mount the motor a little higher even with the old prop.

 

[bcomer]

Re: Changing outboard 1978 85HP to 1988 88 HP

Thanks for this info. The 78 did not have trim but the 88 does. Will the wiring for a trim switch be in the harness for old motor or will I have to run new wires?

 

[Dhadley]

Re: Changing outboard 1978 85HP to 1988 88 HP

You'll have to run wires. A red, blue & a green. 2 more if you want a guage. Actually there are some kits available for adding a switch.

 

[ezeke]

Re: Changing outboard 1978 85HP to 1988 88 HP

I believe that you are misinformed on the 1978 85HP gear ratio, bcomer. The stock propeller ratio was 13:26. on the V4 lower units for that year.

 

[bcomer]

Re: Changing outboard 1978 85HP to 1988 88 HP

There is a web site listed in this forum that I went to and looked up both motors. Here is what they displayed for the two engines. My main question is the interchanability of the prop from a fit standpoint and the effect of different drive ratios--if in fact they are different.

Motor Specs
Manufacturer: Evinrude
Model: "88 SPL; 88 SPECIAL"
Year: 1988
Horsepower: 88.0
Cylinders: 4
Type: 2 stroke
Gear Ratio: 2.00:1
Min WOT RPM: 4500
Max WOT RPM: 5500
Spline Count: 13
Drive Type: Outboard

Motor Specs
Manufacturer: Evinrude
Year: 1978
Horsepower: 85.0
Cylinders: 4
Type: 2 stroke
Gear Ratio: 2.29:1
Min WOT RPM: 4500
Max WOT RPM: 5500
Spline Count: 13
Drive Type: Outboard

 

[ezeke]

Re: Changing outboard 1978 85HP to 1988 88 HP

I have attached a copy of specification page 2-3 from OMC factory service manual # 506753, which covers the 1978 85HP Evinrude models 85899, 85895 and 85890.

If you give me the link, I'll share the information so that they can correct it.

 

[bcomer]

Re: Changing outboard 1978 85HP to 1988 88 HP

I found the link in one of the posts but not sure where. Tried looking for it but can't find again. Don't remember what key words I used when searching that time--did many different searches.