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Posted

Finally found a 2009 boat and motor I want BUT....it has a used 2009 Yamaha 90 4 stroke that came with the boat new.. It has 500 hours but compression readings are ALL  150.. I read that 4 stroke compression should be 180-210.  What do you make of this compression ? The boat is 4 hours away, with all the cylinders reading the same @ 150, should I believe this is ok & test drive the boat ? Or should I just run.

I had alot of questions so the dealer asked the owner call me & naturally the owner said it ran great and never had a problem. Trading it in on a new boat. (lets say I am not very trusting when it comes to lots of money) darn It I wish I could just afford new !

Posted

A lot of it depends on the way they took compression test, was it cold, or was it warmed up. Also gauges will read different. On my last boat i tested my compression and only about 95 on each hole with my gauge, then i rented one from Orielly and they were all up around 120.  Petty sure when i had my 60 fourstroke i did the test and it was around 160

Posted
  On 6/15/2020 at 9:20 PM, aarchdale@coresleep.com said:

A lot of it depends on the way they took compression test, was it cold, or was it warmed up. Also gauges will read different. On my last boat i tested my compression and only about 95 on each hole with my gauge, then i rented one from Orielly and they were all up around 120.  Petty sure when i had my 60 fourstroke i did the test and it was around 160

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That is encouraging.Thanks for your reply.  Not actually being there (4 hr drive) I can only research so much from here. I am planning on driving the 4 hrs & test driving tomorrow morning.

I JUST read this "

"""Four-Stroke results should be somewhere in the 180-210 PSI range. These are good readings. Now it is important to note here that you might see 150 or 160 PSI on certain engines when doing this test.

This will allow more air into the system, and you should see the readings come up to that 180 or so range.""""

Posted

Thanks.. by the way, I also read that 4 strokes dont smoke ? Is THAT true ?

Posted

Makes sense since oil is not suppose to be in the gas..(like a 2 stroke).. ;)

Posted

I have never had a smaller motor like this 90 4 stroke. Looking forward to putting it thru MY erratic driving !
I will report back tomorrow night. Hope I get the answers I NEED, not necessarily what I want to hear... I have no problem driving back empty handed. At least I take my camera gear with me so it wont be a wasted trip.. One cool pic makes it worth it. Bringing back a boat even better !!!

Posted
  On 6/15/2020 at 9:38 PM, aarchdale@coresleep.com said:

Im sure Fishinwrench will chime in shortly and give you better advice than me

 

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Anyone here that is even considering purchasing an 11 year old 4-stroke outboard..... kinda proves that nobody is listening to ME. 

So nope, I have nothing useful to add. 😎 

When I said that I have yet to see a 4-stroke powerhead last longer than its very first set of spark plugs.....I was being serious.

Posted
  On 6/16/2020 at 2:04 AM, fishinwrench said:

Anyone here that is even considering purchasing an 11 year old 4-stroke outboard..... kinda proves that nobody is listening to ME. 

So nope, I have nothing useful to add. 😎 

When I said that I have yet to see a 4-stroke powerhead last longer than its very first set of spark plugs.....I was being serious.

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Ok, Ill put you down in the "JUST RUN" column !

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