1994 112 johnson special, blown cylinder? What now?

[Shwinkyyy]

Hello everyone,
I have this outboard as mentioned in title. Has an idle issue, runs great when your giving it gas, but as soon as I bring it to idle she cuts out dead. My buddy ran a compression test.
120
120
120
85
My buddy is going straight to saying she is shot. I'm not too experienced with this so do I just repower? Or has this scenario been salvageable before?

 

[racerone]

Very , very common problem.-----You need 4 new o/s pistons.-----If you can repair it yourself it can be worthwhile.----Not many shops will tackle a rebuild on these.

 

[cyclops222]

What part of the engine has failed ? Gasket ? Loose head bolts ? Broken piston rings ?
Me I would readjust the idle speed screw and idle mixture screw. Good enough. Is it a 4 or 2 stroke engine ?

 

[stresspoint]

85 on one cylinder is not the end of the world .
drop a few mil of oil in that cylinder , recheck compression , if it comes up a bit its probably just rings if so: link and sync her up and run her till she drops dead.

it could be a number of things but a good guess would be rings are worn.
if you could get someone to scope it and take a look for scoring to the bores that would give a better indication to engine condition than just a compression test.
also a plug chop test will indicate if that cylinder is actually what's causing the erratic idle.

compression tests are not the be all and end all to tell a motor condition.

 

[racerone]

Doubt you will find idle mixture screws on this 2 stroke motor !----Bad design of top piston ring.----Take head off and post picture of what you see.

 

[Shwinkyyy]

So my co worker is letting me borrow his endoscope. I'm going to go in there and take a look today and post up what I see in here, other than obvious scoring on the cylinder, anything else I should be looking for?

 

[racerone]

Damage to top of piston and the cylinder head.----Much easier to take the head off.----Motor is no good the way it is now.----So might as well take the head off.---Just 10 bolts and so easy !

 

[Shwinkyyy]

Apologies for the pixelation it's not too easy to get a nice clear shot, but I think I found my culprit. Looks like a nice score on the side of cylinder wall.

 

[Shwinkyyy]

That's the clearest one I can get.

 

[racerone]

The head needs to come off.----There is no magic to this.----Motor needs 4 new O/S pistons / rings.

 

[tphoyt]

That looks pretty deep.
As said it’s best to pull the head and get a real good look at this before doing anything.

 

[racerone]

I think there have been about 124,953 motors with this typical failure !!

 

[Faztbullet]

Either fix it or trade it in

 

[ct1762@gmail.com]

2 customers dropped their motors off in my bone pile last week. both V4 xflows and both with the "misplaced" ring issue. i include a can of engine tuner with every rebuild and forbid them to use any fuel older than 6 weeks

 

[cyclops222]

Pass

 

[stresspoint]

looks a bit deep for a re bore , may need a sleeve , unless the motor has sentimental value , scrap that power head and find a good used one and bolt it to the LU.

 

[saltchuckmatt]

Part it out....get an account with eBay and sell it to someone in fiji.

Then fly there and personaly hand them the parts.

Some motors are meant for stew!

 

[racerone]

These are a great smooth running simple motor.----Easy to maintain and repair.-----Do not need $150 / hr dealer support.

 

[saltchuckmatt]

You can make 10 times what the outboard is worth sending it on eBay.

World wide there is 1,234,567 of these motors and maybe more. Then go buy a good used one and take your significant other out to dinner!