Checking out a '77 Johnson 85hp tonight...what to look for?

[Gas Giant]

Like the title says, I am going to look at a 1977 85hp Johnson motor tonight. As the engine sits right now, it needs the carbs cleaned/rebuilt according to the seller - it ran smoothly 6 months ago, and then sat, and now it runs with a miss. I don't have a lot of money to work with; this engine is in my price range and its not far from where I live.

What should I check for when looking at an older engine? I am going to run a compression check - the seller said this was ok - and I've read JB's post on checking compression several times.

Anything else I should be looking for? Any red flags or warning signs?

Thanks in advance!

 

[metriccrescentwrench]

Re: Checking out a '77 Johnson 85hp tonight...what to look for?

If it has a "miss" it could need anything from an inexpensive carb rebuild kit to very expensive ignition components (for instance, the power pack for that engine is listed as "not available" from BRP). Until you are able to spend time with a factory service manual diagnosing the problem it's just a shot in the dark.

If it's such a cheap and easy fix, why hasn't the guy selling it fixed it already?

 

[Gas Giant]

Re: Checking out a '77 Johnson 85hp tonight...what to look for?

Good point - not sure!

 

[DargelJohn]

Re: Checking out a '77 Johnson 85hp tonight...what to look for?

Run it on the water muffs until it's warmed up. Touch each of the cylinder banks; you should be able to keep your finger there for a count of three. The water jacket between the cylinder banks should remain cool to the touch. Look for discoloration or peeling paint on the heads and cylinder jackets, sometimes a sign of past overheating. Check the tell tail stream, if it has one.

A miss could be a "lean sneeze" which means low idle jets are dirty. Carb rebuild should fix that.

 

[eavega]

Re: Checking out a '77 Johnson 85hp tonight...what to look for?

A couple of easy things to check;
Spark. Rig up a spark tester and make sure you are getting a strong spark. Additionally you can set up a timing light to verify the miss might be carb related.
While you are messing with the spark plugs, pull rhem off and make sure they don't indicate a problem (melted, wet, shiny clean...)
Drain off some oil in fron the LU and make sure it is the right color and not contaminated wirh water.
Check under the hood for signs of overheat conditions (scorch marks or anything that looks melted or discolored.)
If its a saltwater motor, look for obvious signs of corrosion, especially around the head bolts.
Check that the motor can go into forward, reverse, and neutral.

These are checks I've performed on motors I've purchased. In some cases just the suggestion that I was going to perform these checks have been enough to cause potential sellers to confess the known issues with the motors they had conveniently "forgotten". Also the more you know about the motor's potential pitfalls, the better your negotiating position.
Good luck