1980 115 johnson stumbles at 2500rpm low compression cyl 3

[TA2RTIST]

as the title states, po said it starts and runs but once its under load it wont go, just picked up this 87 charger with the 115 johnson v4? anyway was told what I stated have not recreated for myself yet, seems to be untouched, this is the post I replied to.

1987 charger bass boat with 1980 Johnson 115 v4. Motor has good working tilt and trim and a solid boat transom but has a dead cylinder. So the motor will need a new power head or rebuilt.

I'm a noob when it comes to boats, have built several cars and motorcycles, no stranger to rebuilding motors, question is how do yall take the above post? the guy was very open and honest with me I don't believe he was lying, i bought it all for 500.00 so I don't mind spending a few bucks.
any tips tricks where to start as it were? anything super weird in comparrison to auto/cycle motors?
thanks yall this is my first boat and im excited to get it going

 

[havoc_squad]

as the title states, po said it starts and runs but once its under load it wont go, just picked up this 87 charger with the 115 johnson v4? anyway was told what I stated have not recreated for myself yet, seems to be untouched, this is the post I replied to.

1987 charger bass boat with 1980 Johnson 115 v4. Motor has good working tilt and trim and a solid boat transom but has a dead cylinder. So the motor will need a new power head or rebuilt.

I'm a noob when it comes to boats, have built several cars and motorcycles, no stranger to rebuilding motors, question is how do yall take the above post? the guy was very open and honest with me I don't believe he was lying, i bought it all for 500.00 so I don't mind spending a few bucks.
any tips tricks where to start as it were? anything super weird in comparrison to auto/cycle motors?
thanks yall this is my first boat and im excited to get it going

The key issue now is expense. It greatly depends on where you live, if you live in an area where there is a lot of used outboards for sale, one would probably be better off finding a good used one for sale.

To properly rebuild a powerhead on an Evinrude/Johnson V4 90 degree crossflow in the US assuming it is a 100% good core, you're probably looking at minimum $1200 just in parts on the powerhead alone.

Bearings and entire piston kits required along with gaskets. No re-ringing on two stroke motors.

If any of the cylinders have to be oversized greater than 20 thousandths, you'll have to change the idle, intermediate, and main jet size for that carb & cylinder to deliver the extra fuel required to make up the extra cylinder volume due to the oversize.

Not to mention you'll probably get hit fairly hard on shipping costs if you have to ship out the block and heads to machine shop.

I would say you'd probably come out fortunate if you could keep it under $1600 in parts & machine shop work with shipping (not including taxes) for a V4 90 degree crossflow if you put the motor together yourself.

 

[racerone]

Broken rings is something that happens to these V-4 cross flow engines.----Every engine will suffer from it.-----You need 4 new O/S pistons.

 

[jimmbo]

Welcome to iboats
Have you done any tests on the engine?
First thing to do is a Compression Test. If the engine does indeed have a no/low compression Cylinder(s) then you need to decide, rebuild or replace the Powerhead, or even the entire engine, as there are a lot of other used ones available. Of course that just means you could buy another Engine with similar or worse problems. If yo decide to rebuild, you still would have to determine what caused the failure, or in a few hours of running you may once again have a pooched engine
Then see if the Ignition System can produce a Spark that can jump a 3/8" gap.
Fuel System is a bit more complicated to inspect, but a Bog around 2500 could indicate a Leanness in one or more of the Carbs, likely from dirt/gum/varnish, in the Main Circuits in the Carbs.
Also inspect the Gearcase for Water Intrusion, by opening the Drain screw and observe what comes out. The Options are Oil, Water, then Oil, or a liquid that looks like Irish Creme. Only Oil, is the correct answer.

 

[racerone]

Just finished helping a dealer with a bad V-4 powerhead.-----Replaced powerhead and installed it at the dealers workshop.-----Got compliments and $200 extra with a " thank you very much " for helping out.

 

[jimmbo]

No offence intended.
Doesn't the dealer have Mechanics of it's own?

 

[racerone]

Yes-----But they no longer rebuild older ( 1984 ) motors.-----Motors are older than the mechanics.----Owners of older motors will howl and complain at the cost to fix these motors.-----Owners of $80,000 boats will say " thank you " when they see an invoice for $700 for service work.

 

[racerone]

Mechanic at dealer was working / doing service work on a 300 HP E-TEC G2 on a silvery 20'+boat.----Also the 25 HP E-TEC on the same boat.------6 hrs on that will generate painless revenue.-------An early 80's V-4 and the owner are not popular at big shops !!

 

[jimmbo]

They actually require some Knowledge, and some Skill to actually repair, instead staring at a Laptop screen and Swapping Parts until the Problem is Solved

Not everyone is making CEO Salaries, but many items are priced like Everyone is

 

[ct1762@gmail.com]

The key issue now is expense. It greatly depends on where you live, if you live in an area where there is a lot of used outboards for sale, one would probably be better off finding a good used one for sale.

To properly rebuild a powerhead on an Evinrude/Johnson V4 90 degree crossflow in the US assuming it is a 100% good core, you're probably looking at minimum $1200 just in parts on the powerhead alone.

Bearings and entire piston kits required along with gaskets. No re-ringing on two stroke motors.

If any of the cylinders have to be oversized greater than 20 thousandths, you'll have to change the idle, intermediate, and main jet size for that carb & cylinder to deliver the extra fuel required to make up the extra cylinder volume due to the oversize.

Not to mention you'll probably get hit fairly hard on shipping costs if you have to ship out the block and heads to machine shop.

I would say you'd probably come out fortunate if you could keep it under $1600 in parts & machine shop work with shipping (not including taxes) for a V4 90 degree crossflow if you put the motor together yourself.

i've built a few .030'' over and never needed to re-jet. Cant hurt to go up a size but for an extra $250 in jets its not really an issue. I do take 2 degrees of timing out for break-in (just 2 hours).

 

[jimmbo]

The extra displacement by a 0.30" overbore is almost Insignificant, and the Main Jetting is always a tad on the Rich Side.

 

[ct1762@gmail.com]

The extra displacement by a 0.30" overbore is almost Insignificant, and the Main Jetting is always a tad on the Rich Side.

well put thanks. also, the jets do wear themselves a bit over the years or so im told never actually compared to a new one.

 

[racerone]

Well ----I do not think the brass jets wear out.----But some folks are desperate for a story when motor does not run properly.

 

[jimmbo]

I guess if Gasoline flowed thru the jets for a few thousand years, there might some erosion

 

[ct1762@gmail.com]

ha didn't think so. one guy claimed they can get up to 3-4 sizes larger.Never worried me.