"Jim and Becky" wrote in message
...
Anyone know what psi reading I should expect on these 1988 200's?
On a new engine?
An engine that I probably don't want?

You should not be concentrating on absolute compression reading, The
compression reading will depend on humidity, air pressure, cranking speed
(battery charge) and a host of other factors. You should be concentrating
on the difference between the cylinders, a range within 5 psi is what you
ared looking for.

OK I agree, but if all six cylinders have 70-80 psi isn't there a problem?
I'm thinking the 120-140 psi range is what I'm looking for based of
something I read long ago.
Hence my latest question.


"Mark" Boatbasin@optonline(remove this).net wrote in message
...

"Jim and Becky" wrote in message
...
Anyone know what psi reading I should expect on these 1988 200's?
On a new engine?
An engine that I probably don't want?

You should not be concentrating on absolute compression reading, The
compression reading will depend on humidity, air pressure, cranking speed
(battery charge) and a host of other factors. You should be concentrating
on the difference between the cylinders, a range within 5 psi is what you
ared looking for.

It depends on the engine and what the manufacture lays out to you. 5
PSI may be acceptable for some engines and not others. It will be in
the "book". Or at least it should be.

On Tue, 1 Feb 2005 21:32:14 -0500, "Jim and Becky"
wrote:

I'm pondering (always will be) a boat with a pair of 1988 Yamaha 200's.
The seller says they have 1025 hours on them.

I have four of these on my 26' ranger. darn good engines.

Assume they weren't used commercially and have been well taken care of.
What is the life expectancy (total hours) of these?

These will run for 102k hours beforte a top end rebuild is needed.
look at a bottom end rebuild after about 600k hours.

Lets say we call them obsolete when they drop more than 15% of their
original output. I'm in an area I know nothing about but some power loss
might be expected due to worn pistons, etc.

One of thae bad things about these engines, it that the cams wear
down. this is where the power loss comes from. Simply replace the
cams, and you will be back at full power.

All I can think of is one motor dying about the first of July and getting
the boat back in the water around mid September.
I remember reading 10,000 hours for an inboard gas, maybe twice that for an
inboard diesel?

More like four times more. At least, that has been my experience.