1977 85 H.P. Evinrude Model # 85895C S# J0003143. Low idle issue.

[banchigu]

Good Evening Good People...
I have a question. I have a 1977 85 H.P. Evinrude Model # 85895C
S# J0003143.

It runs like a scalded cat, however, when I run it at low speeds under 5MPH after about 10 minutes is bogs down and dies on me, it starts right up but it seems to flood when I want to accelerate. If I start it and punch the throttle it will take off sometimes but I do not like doing that, not safe, so If I let it sit for maybe 15-20 minutes it will run again just fine.
I like to troll deep baits when the summer temps hit 100F but I cannot for long periods of time.

A gent on here told me a few years back that I needed to change the idle screw he gave me some sizes. In my notes of a few years back I noted this...
.024, .023, and .032. However, I do not know if the engine has .023 -.024 idle screws and I need .032 or vise versa.

I also run it a bit rich and run synthetic oil out of it.
I also made a notation Low Speed Idle Orifice, But I have not clue what do do with that information.

As I mentioned I jotted this down about 4 plus years ago and since then I went though a divorce and well I have forgotten what I needed to do.
Thanks to everyone in advance.

 

[racerone]

Some will argue.-----Step #1 is to post the results of a compression test.

 

[jimmbo]

Some will argue.-----Step #1 is to post the results of a compression test.

No Argument from me.
It is a Great Way to determine if it worth putting any Time and/or Money(or as you say. "Beer Tokens") into an Engine

 

[Mc Tool]

A hot comp test . Dunno so much about outboards but 2 stroke motorcycles that are getting a bit tired tend to loose power noticeably once up to temp.
It may be a bit of tiredness combined with excess fuel/oil that causes a bit of puddling , gotta remember that while low comp tested in the compression chamber also reflects low primary compression and there might not be quite enough puff to keep the bypass clear at idle speeds indefinity. Knackered reed valves wont help either.......only takes one .
Years ago I had an early ish (87 ish ) 150hp Zuki and it was a pig to troll with coz it would eventually bog down , bit of fast idle lever and the back of the boat would be enveloped in smoke as it chugged its way back to life and it would be good for another 4-5 mins ..... it really was a piece of crap for a lot of other reasons too .

 

[jimmbo]

Low Crankcase Compression is not revealed during a Cylinder Compression Test

 

[Mc Tool]

Low Crankcase Compression is not revealed during a Cylinder Compression Test

No , which is why I mentioned it , but surely its implied . If the cyl/ bore wear or damage is such that it causes excess pumping inefficiencies it wouldn't it be in both directions ? especially at low speeds , and when the motor is bogging down they can get pretty slow .

 

[jimmbo]

It wouldn't be revealed in a Cylinder Compression Test, as Air can enter the Cylinder via the Exhaust Ports, instead of via the Crankcase. Crankcase Compression Ratios are even lower than Cylinder Compression Ratios, and Maybe a Reading can be obtained off a Fuel Pump Port for one of the Crankcases.

 

[Crosbyman]

hard to see on parts list but does this animal have any recirculation hoses or possibly plugged up recirc hoses ??

 

[racerone]

???----Well , there are no hoses.---- Internal passageways recirculate oil on the 3 cylinder inline models, and also the V-4 and V-6 cross flow motors.-----

 

[Crosbyman]

same question then any chance a problem could develop at that level ?

 

[racerone]

The original poster needs to establish the condition of this 47 year old motor.-----Many owners pick on the carburetors as a first step.----Posting the compression values can lead to a process to get this motor back on the lake.-----Does spark jump a gap of 3/8" on each lead ?-----Waiting for info.---And sorry If I sound blunt.

 

[Mc Tool]

Compression Ratios are even lower than Cylinder Compression Ratios, and Maybe a Reading can be obtained off a Fuel Pump Port for one of the Crankcases.

Yeah thats one thing I see different between motorcycles and outboards . Most of the bikes have a lot less crankcase volume and thusly higher primary compression . And looking at some of them crossflow motors they seem real primitive port wise.
I used to fix race carts with the old Johnson D400 iron horse engines ( it was a class here ) and whilst they were supposed to be unmodified there was a bit of jiggery pokery goin on inside them cases and ports .

 

[banchigu]

Some will argue.-----Step #1 is to post the results of a compression test.

Compression test was A-OK all cylinders were well within compression limits. 128. 127, 130, and 129

 

[banchigu]

The original poster needs to establish the condition of this 47 year old motor.-----Many owners pick on the carburetors as a first step.----Posting the compression values can lead to a process to get this motor back on the lake.-----Does spark jump a gap of 3/8" on each lead ?-----Waiting for info.---And sorry If I sound blunt.

Thank you so much,

Engine is in really good shape fires right up and had been well cared for.

Compression test was A-OK all cylinders were well within compression limits. 128. 127, 130, and 129

Gaps were all correct, and plugs were correct.

Hope this helps.

 

[banchigu]

Thank you so much,

Engine is in really good shape fires right up and had been well cared for.

Carbs were all overhauled with new parts.

Compression test was A-OK all cylinders were well within compression limits. 128. 127, 130, and 129

Gaps were all correct, and plugs were correct.

Hope this helps.

 

[racerone]

Checked fuel pump diaphragm ?----Checked flywheel key?-----Checked thermostat ?

 

[cyclops222]

I can overhaul a Nuclear Reactor.
1 time.

 

[racerone]

Actually I assembled / tested some components for a nuke plant.-----Then got a job at one as well.

 

[Mc Tool]

Checked fuel pump diaphragm ?----Checked flywheel key?-----Checked thermostat ?

Ha I was just thinking flywheel key , I was thinking of my iron horse post and that other dude with the mashed lower gear case and remembered I was forever replacing flywheel keys on rotary lawn mowers and wondered if it was an issue for outboards. The one on my Tohatsu is a massive slab or steel.

 

[racerone]

The flywheel key is very small on these outboards.-----It's job is to locate the flywheel for timing.----The flywheel is driven by locking tapers.-----Imagine a 9.9 HP and a 300 HP using the same key !