70hp compression

[Dennischaves]

ive been having some issues with my 1984 70hp
bogging out when I apply throttle
I just bought a new compression gauge to
I'm getting readings of 93 92 90
its a harbor freight compression gauge but those numbers just seem way to low?

 

[flyingscott]

Get a different gauge and retest. Yes those numbers are very low, on an original never rebuilt motor I would hope to see above 110. Anything under 100 is not going to run right.

 

[racerone]

I would want to see 140 PSI on my tester.----Take the head off.-----Head gasket is cheap.

 

[Dennischaves]

what should I be looking for when I pull the head off?

 

[flyingscott]

A brand new or rebuilt motor will have 140 psi compression. A used one that has some hrs on it will NOT get a discount different tester. Then if the #s are the same pull the head.

 

[racerone]

Just pull the head off.----Post some pictures of cylinder walls.----Head gasket is cheap.-----Just 18 bolts and you may have an answer !!

 

[tbfosback]

i just picked an outboard myself. the seller tested the compression on a Harbor Freight gauge as well. He got 70lbs in each cylinder. i brought it home and got 115lbs even on my old Mac tools gauge.
point is that every gauge is different. the harbor freight ones.. you get what you pay for..
But everyone is correct.. head gaskets are cheap if you don't have a borescope.

 

[racerone]

I can't believe folks will rush out and buy $300 stators / coils / powerpacks like a blind squirrel.-----A $30 head gasket is cheap.

 

[Dennischaves]

im not going to jump to anything until I pull the heads and I think im going to by a better compression tester too

 

[ct1762@gmail.com]

I'm sure most of us that work on these for a living have gone through atleast a dozen gauges. i've had great luck with the $20 Lisle ones. Seem to be the most accurate. FYI careful with those head bolts! Just got done taking the head off an 85' 70 and 3 bolts snapped, 2 were so frozen in the block 1,000ft lbs impact gun wouldn't budge them until I used a bolt extractor in salt water though.