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1973 135 HP Johnson 135ESL73M acceleration/start problems

M

Michael Bergum

New member
I am hoping to get a wee bit of feedback. I have a 1973 Johnson 135HP motor. I've owned it for about 2 years now.

It has alway been terrible to cold start, I've tried many different techniques, but I usually alway flood the motor and wind up swapping the spark plugs to get it up and running. Once it starts though it always starts right away.

It has recently started to seem to lack power. If I have new plugs, it has no problem getting to plane and cruising along. Once I've used then a time or two, the boat just bogs again.

I am thinking about rebuilding the carbs but I don't know where to start.

Any thoughts?
 
Report the results of a compression test.-------If an outboard is " hard to start " then there is something wrong.
 
Sorry for the delay - I've just now had a few minutes to get the boat out of the garage and take a look at it.

Here are the compression tests:

C1- 142
C2- 110
C3- 144
C4- 140

I did this with the motor cold, plugs out.

I have great spark.

The low compression on C - 2 worries me - I tested several times and all very similar readings. Battery was @ 100%

Should I be worried about piston/rings? How can I check?

Thanks guys!
 
Remove the bypass cover for the cylinder that is low on compression.-----Takes just a few minutes to inspect the piston and rings.--------Likely you will need a cold one after you take a look in there.----Very common for the top ring to be missing / broken.
 
racerone said:
Remove the bypass cover for the cylinder that is low on compression.-----Takes just a few minutes to inspect the piston and rings.--------Likely you will need a cold one after you take a look in there.----Very common for the top ring to be missing / broken.
Click to expand...

I was worried someone would say that - I'll remove it tonight and take a look - if I can get pictures, I'll post.

If it is a ring issue - is it worth replacing rings? The motor is in great shape.
 
Now the 73 model year is unique in that pistons from 72 do not fit and pistons from 74 will not fit.-----Pistons were the same from 74 to the late 1990's models.---Post when you have more info.
 
Last edited:
racerone said:
Remove the bypass cover for the cylinder that is low on compression.-----Takes just a few minutes to inspect the piston and rings.--------Likely you will need a cold one after you take a look in there.----Very common for the top ring to be missing / broken.
Click to expand...


Alright - I removed the cover - see the pictures. Your thoughts? 20150602_161834.jpg20150602_161827.jpg20150602_161906.jpg

It's the top cylinder.
 
It appears you removed the cylinder head instead of the bypass cover.------Motor has to come apart for repairs.
 
Last edited:
racerone said:
It appears you removed the cylinder head instead of the bypass cover.------Motor has to come apart for repairs.
Click to expand...


What would have buggered up the piston head? It appears the rings are still intact?


I am assuming I'll need to replace piston and rings? I have another powerhead available, can I use a good piston from there?

Is it worth it? What is the likelihood I get done and the dang thing still doesn't work?
 
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