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Jan 23rd, 2013
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Compression Report Thoughts #12544370
12/20/17 02:15 AM
12/20/17 02:15 AM
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Argyle, TX
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TexasTechsan Offline OP
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I'm looking at a boat that has a 2014 250 SHO on it. I had the seller take it in to get a compression test done.
Below are the readings. I always have used the rule of thumb where readings should be no more than 10% of each other.
This report shows a larger variance than id like but the mechanic stated its within spec and variance was caused by fogging oil present. Thoughts?





2014 Skeeter FX21 (Red & Black)
Re: Compression Report Thoughts [Re: TexasTechsan] #12544529
12/20/17 04:27 AM
12/20/17 04:27 AM
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Argyle, TX
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TexasTechsan Offline OP
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I'm having the seller get the test again after I test drive the boat. That should burn off the fogging oil and the test readings should be accurate. How worried would you all be after seeing the initial compression report? Is it truly within spec, like the tech noted, with readings of 160psi-180psi?


2014 Skeeter FX21 (Red & Black)
Re: Compression Report Thoughts [Re: TexasTechsan] #12544623
12/20/17 11:43 AM
12/20/17 11:43 AM
Joined: Apr 2017
Posts: 1,418
San Angelo
tmd11111 Online content
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To do a proper compression test the tech should have ran the motor up to operating temperature first. This would have burned off all fogging oil and gave a true reading.

Re: Compression Report Thoughts [Re: TexasTechsan] #12544628
12/20/17 11:57 AM
12/20/17 11:57 AM
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Dallas, Texas
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Cat finder Offline
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This^^^


If the fish don't bite your not baiting right...
Re: Compression Report Thoughts [Re: TexasTechsan] #12544675
12/20/17 01:24 PM
12/20/17 01:24 PM
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Posts: 11,510
Littlefield Tx & Lake A. H. US...
gary purdy Offline
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I am concerned about the motors abuse. 6984 rpm`s for 10.6 min. and over-rev-count for 51.6 min. Like already said the motor should have been run before the compression test. Any oil in a cylinder will normally make the cylinder show higher compression. This motor doesn`t have a lot of factory warranty left. I will add that Yamaha has been really good at taking care of these SHO motors even when problems occur just out of warranty.


The world will not be destroyed by those who do evil, but by those who watch them without doing anything. Remember what He has done and remember that He is not done yet!-- GOD IS GOOD
Re: Compression Report Thoughts [Re: tmd11111] #12544733
12/20/17 02:16 PM
12/20/17 02:16 PM
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Posts: 59
Argyle, TX
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TexasTechsan Offline OP
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Originally Posted By: tmd11111
To do a proper compression test the tech should have ran the motor up to operating temperature first. This would have burned off all fogging oil and gave a true reading.
I agree and that's why I'm having the seller take it back up to get it looked at again. Seems like poor workmanship not to 're run the test correctly before writing up the report. Thanks for the reply!


2014 Skeeter FX21 (Red & Black)
Re: Compression Report Thoughts [Re: gary purdy] #12544735
12/20/17 02:18 PM
12/20/17 02:18 PM
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Argyle, TX
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Originally Posted By: gary purdy
I am concerned about the motors abuse. 6984 rpm`s for 10.6 min. and over-rev-count for 51.6 min. Like already said the motor should have been run before the compression test. Any oil in a cylinder will normally make the cylinder show higher compression. This motor doesn`t have a lot of factory warranty left. I will add that Yamaha has been really good at taking care of these SHO motors even when problems occur just out of warranty.
I noticed that in the report but thought something wasn't right because in the RPM/Hour section of the report it says that the engine has nobhours between 6,000-7,000 toms. Something looked off about all of it.


2014 Skeeter FX21 (Red & Black)
Re: Compression Report Thoughts [Re: TexasTechsan] #12545022
12/20/17 05:25 PM
12/20/17 05:25 PM
Joined: Apr 2017
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San Angelo
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Originally Posted By: TexasTechsan
Originally Posted By: gary purdy
I am concerned about the motors abuse. 6984 rpm`s for 10.6 min. and over-rev-count for 51.6 min. Like already said the motor should have been run before the compression test. Any oil in a cylinder will normally make the cylinder show higher compression. This motor doesn`t have a lot of factory warranty left. I will add that Yamaha has been really good at taking care of these SHO motors even when problems occur just out of warranty.
I noticed that in the report but thought something wasn't right because in the RPM/Hour section of the report it says that the engine has nobhours between 6,000-7,000 toms. Something looked off about all of it.




According to the report i has 51 minutes over 6000 rpms. Report in rpm increments is by hours. 9 more minutes over 6k and it will show 1 hour. Gotta wonder as to why or how it was rev'd to almost 7k rpms though.

Re: Compression Report Thoughts [Re: TexasTechsan] #12545071
12/20/17 05:51 PM
12/20/17 05:51 PM
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Posts: 606
Wylie
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Have them do a leak down on motor on a 4stroke that tells you more than compression will those motor are made to run over 6000


Hughes Marine Service
Wylie ,Texas
Re: Compression Report Thoughts [Re: tmd11111] #12545098
12/20/17 06:18 PM
12/20/17 06:18 PM
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Argyle, TX
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TexasTechsan Offline OP
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Argyle, TX
Originally Posted By: tmd11111
Originally Posted By: TexasTechsan
Originally Posted By: gary purdy
I am concerned about the motors abuse. 6984 rpm`s for 10.6 min. and over-rev-count for 51.6 min. Like already said the motor should have been run before the compression test. Any oil in a cylinder will normally make the cylinder show higher compression. This motor doesn`t have a lot of factory warranty left. I will add that Yamaha has been really good at taking care of these SHO motors even when problems occur just out of warranty.
I noticed that in the report but thought something wasn't right because in the RPM/Hour section of the report it says that the engine has nobhours between 6,000-7,000 toms. Something looked off about all of it.




According to the report i has 51 minutes over 6000 rpms. Report in rpm increments is by hours. 9 more minutes over 6k and it will show 1 hour. Gotta wonder as to why or how it was rev'd to almost 7k rpms though.
That makes sense about it not reading 1 full hour yet at 6000+rpms. Wonder why the other rpm ranges have the decimal point but under 1000 and over 6000 do not? Im concerned about the high rpm as well. I'm working to get an answer.


2014 Skeeter FX21 (Red & Black)
Re: Compression Report Thoughts [Re: boatman025] #12545101
12/20/17 06:20 PM
12/20/17 06:20 PM
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Posts: 59
Argyle, TX
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TexasTechsan Offline OP
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Originally Posted By: boatman025
Have them do a leak down on motor on a 4stroke that tells you more than compression will those motor are made to run over 6000
I'll ask to get this leak down test done. I would have been as concerned had the boat been run at 6000-6200rpms but almost 7k makes me iffy on the deal. Thanks for the recommendation.


2014 Skeeter FX21 (Red & Black)
Re: Compression Report Thoughts [Re: TexasTechsan] #12546977
12/22/17 01:46 AM
12/22/17 01:46 AM
Joined: May 2003
Posts: 11,510
Littlefield Tx & Lake A. H. US...
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Limiter is 6250. Yamaha recommends you run the SHO at higher RPMs on top and be propped correctly. Ideally 5800-6000 at WOT. Bearing failures have occurred due to under propped rigs putting the motor in a strain. Found this out yesterday from Yamaha and my Yamaha Master Technician.


The world will not be destroyed by those who do evil, but by those who watch them without doing anything. Remember what He has done and remember that He is not done yet!-- GOD IS GOOD
Re: Compression Report Thoughts [Re: gary purdy] #12547345
12/22/17 12:21 PM
12/22/17 12:21 PM
Joined: Apr 2017
Posts: 1,418
San Angelo
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Originally Posted By: gary purdy
Limiter is 6250. Yamaha recommends you run the SHO at higher RPMs on top and be propped correctly. Ideally 5800-6000 at WOT. Bearing failures have occurred due to under propped rigs putting the motor in a strain. Found this out yesterday from Yamaha and my Yamaha Master Technician.


Got that backwards. Under propped will let the motor over rev with little strain. Over propping will put a strain on the motor due to not being able to reaching optimal rpm range.

Re: Compression Report Thoughts [Re: tmd11111] #12547532
12/22/17 02:44 PM
12/22/17 02:44 PM
Joined: May 2003
Posts: 11,510
Littlefield Tx & Lake A. H. US...
gary purdy Offline
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Littlefield Tx & Lake A. H. US...
Originally Posted By: tmd11111
Originally Posted By: gary purdy
Limiter is 6250. Yamaha recommends you run the SHO at higher RPMs on top and be propped correctly. Ideally 5800-6000 at WOT. Bearing failures have occurred due to under propped rigs putting the motor in a strain. Found this out yesterday from Yamaha and my Yamaha Master Technician.


Got that backwards. Under propped will let the motor over rev with little strain. Over propping will put a strain on the motor due to not being able to reach optimal rpm range.
This is relating to high RPM`s causing premature bearing failure. Straining caused from over propping causes piston failure.


The world will not be destroyed by those who do evil, but by those who watch them without doing anything. Remember what He has done and remember that He is not done yet!-- GOD IS GOOD
Re: Compression Report Thoughts [Re: TexasTechsan] #12547777
12/22/17 05:15 PM
12/22/17 05:15 PM
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Wylie
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bump Gary P


Hughes Marine Service
Wylie ,Texas
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