New to me 1987 90hp Johnson

[blimp]

Just picked up a new boat/motor combo and I have a few questions.

1. I have a complete OMC manual (the 700 page big one) from 1984, are there major differences between '84 and '87 in these v4 motors? Will i need to sell this one and get an 87 model year manual?

2. I am planning on replacing thermostats, water pump, and cleaning/rebuilding carbs, general lubing and a link n sync. Any other points I should check out?

3. Tilt and trim are functional, any preventative maintenance i can do to keep them working well?


I am used to a '84 30hp, and this thing is a beast in comparison! Any other tips or impressions of the motor would be appreciated.

It is on a 17' welded aluminum boat, nice step up from my old 14' jon

Thanks in advance!

 

[ezeke]

Re: New to me 1987 90hp Johnson

Most of what is in the 1984 book for the V4 crossflow motors applies to the 1987 90HP crossflow.

The parts that are different will show in the parts catalog which is free and on-line: http://shop.evinrude.com/

The HP rating system is different, so that the 1987 90HP or more like the 1984 115HP.

The PT&T will last longer if you keep the reservoir filled properly. Grease the trim rams and keep them fully withdrawn when not in use so that they don't corrode.

Since the motor is new to you, I would recommend that you treat it as one that has been in storage: http://forums.iboats.com/showthread.php?t=158086

 

[blimp]

Re: New to me 1987 90hp Johnson

Thats good advice. They guy said it was an '84 or '85, i was pretty excited to find out it was an '87 due to the powerhead -> prop hp ratings change.

I ran a compression check and checked the lower unit oil before purchase, and all was good.

compression was between 120 and 130 on all cyl. oil was black, no metal or water in it.

can't wait see how she runs on the water!

 

[ezeke]

Re: New to me 1987 90hp Johnson

Black gear oil is worn out.

Be careful not to over-prop the engine; you should be able to reach 5800 RPM with your average load at WOT; if not you will lug the engine and shorten it's life.

 

[blimp]

Re: New to me 1987 90hp Johnson

I have heard about the lugging issue and how it creates bad temps in the cyl. If it is correctly propped and will reach ~5800rpms at WOT, is it OK to go 1/2 throttle most of the time? Not sure i want to be screaming around the lake all the time...

 

[ezmobee]

Re: New to me 1987 90hp Johnson

Yes. You just need to be able to hit your target range at WOT. That in no way means you need to drive at WOT.

 

[Huron Angler]

Re: New to me 1987 90hp Johnson

My dad had a '87 90hp Johnson and we got many great years of use out of it and eventually sold it with the boat.

They are good outboards if well maintained.

That 17' flat-bottom will absolutely fly with that thing, we had ours on a 20' Sea Nymph aluminum and did around 40mph fully loaded.

 

[blimp]

Re: New to me 1987 90hp Johnson

My dad had a '87 90hp Johnson and we got many great years of use out of it and eventually sold it with the boat.

They are good outboards if well maintained.

That 17' flat-bottom will absolutely fly with that thing, we had ours on a 20' Sea Nymph aluminum and did around 40mph fully loaded.

that is exactly what i was hoping to hear

 

[Huron Angler]

Re: New to me 1987 90hp Johnson

BTW what's the max hp rating for the rig? It might get a bit squirrely with a 90.

 

[blimp]

Re: New to me 1987 90hp Johnson

max is 115, its a modified v, with a sharp v at the bow going to a gentle v towards the stern.

 

[ezmobee]

Re: New to me 1987 90hp Johnson

My '81 90 runs awesome also. Pushes my 18' deep V to 41MPH