pression values Yamaha 70TLRU

[correzio]

I did recently repaired my engine YAMAHA 70 of the year 1996. The model is 70TLRU. I would measure the pressure, but I do not know the optimal or at least acceptable values . I would like some indication.

P.S.: Also what is the value of the compression ratio of my 70TLRU?

Thanks

[rodbolt17]

typically you will see a 10 PSI difference from #1 to #3 when testing.
no specific data is published.

[correzio]

I understand that there are no official data by YAMAHA. I therefore turn to the experience of someone or to an expert.
Again, thank you.

[rodbolt17]

and if Yamaha doesnt publish it,most other manufacturers do the same, why would I?

however on the inline 3 cyl yamaha its not uncommon to see a 15 psi difference from top to bottom.
its the way the combustion chambers are machined.
I actually cc'd one once and sure enough,they were all different.

2 strokes dont wear and lose a bit of compression, EVER.
they work great all the way to the point they blow up.

its not like a car engine,trust me on that.

[correzio]

I measured the values of cold pressure. I found from top to bottom 83, 87, 85 psi. Do you think that is acceptable?
Many thanks

[rodbolt17]

beats me.
I would go with it.
not knowing if your gauge is calibrated correctly no the altitude that you tested nor the ambient air temp of the test.
all will affect the reading.
its why most makers dont have a specification printed.

the first time I ran a compression test on a 225 looper evinrude I got 80 PSI on all 6, borrowed a tester from a friend and got 80 psi again.
called another friend at Ron's marine and was told, yep that is about perfect.

[correzio]

You're right. I have not provided the data: temperature about 20°C (68°F) and air pressure 1015hPa (14.72 psi). My boat is at sea, so the altitude can be considered 0 meters.
Many thanks