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  1. #31
    Join Date
    Nov 2011
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    tennessee
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    Default Re: Cylinder bore question

    All the parts look normal for wear/tear/discoloration. Pistons being scuffed at 6 and 12 is from heat...
    Pappys Sales and Service
    Owner and Factory Certified Technician
    Former racer KDBA (Kentucky Drag Boat Association)

  2. #32

    Default Re: Cylinder bore question

    Quote Originally Posted by racerone View Post
    ????------" weak spark washing away the oil "------Where did that wild idea come from ?-------Just more proof that oil / lubrication inside a 2 stroke is not well understood !!
    I read that on a boat repair forum. I had never heard of that before and thought it did not make a lot of sense but the poster seemed knowledgeable. I figured it was just one of those "you learn something new everyday" deals...

  3. #33
    Join Date
    Sep 2010
    Posts
    19,074

    Default Re: Cylinder bore question

    Well statement like " weak spark washing away the oil " just make me chuckle a wee bit.-----Many folks just do not know how oil works in a 2 stroke or what happens when mixed fuel goes through a carburetor.

  4. #34

    Default Re: Cylinder bore question

    I don't see any thing that would make .022 gouge. The torque specs in your 120/140 service manual are not the same as 110.

  5. #35

    Default Re: Cylinder bore question

    Quote Originally Posted by racerone View Post
    Well statement like " weak spark washing away the oil " just make me chuckle a wee bit.-----Many folks just do not know how oil works in a 2 stroke or what happens when mixed fuel goes through a carburetor.
    What are you talking about? Oil mixes with fuel and provides lubrication to moving parts. Are you privy to some special knowledge of how oil lubricates at the moleculer level that others don't know about? If so maybe you could share your secret knowledge
    I'm still looking for a clue as to why the damage occurred.

  6. #36
    Join Date
    Sep 2010
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    19,074

    Default Re: Cylinder bore question

    Sharp eye to spot the 120 / 140 pages on the work bench.----Any more pictures of those 2 pistons and the other 2 pistons.------The color marking on rod was not due to anything inside the running motor.----More piston pictures needed.

  7. #37

    Default Re: Cylinder bore question

    Quote Originally Posted by baddog1016 View Post
    Is it possible an overheat led to the piston scuffing and then then water pump impeller was replaced prior to unloading the boat?
    That's a good thought but the seller bought a brand new impeller kit but did not install it, it's new in box sitting in the boat.

  8. #38
    Join Date
    Sep 2010
    Posts
    19,074

    Default Re: Cylinder bore question

    Post more pictures of the pistons.------Something tells me there might not be many hrs on the pistons shown so far.

  9. #39

    Default Re: Cylinder bore question

    Will do. I'm trying to arrange a phone call with the seller that might provide ml some clues. He just texted he found the ground wire on the VRO was loose but did not elaborate. When he bought the boat a few years ago he was told the motor was rebuilt. It has standard 3.5" bore.

  10. #40
    Join Date
    Nov 2011
    Location
    tennessee
    Posts
    4,177

    Default Re: Cylinder bore question

    Well statement like " weak spark washing away the oil " just make me chuckle a wee bit.-----Many folks just do not know how oil works in a 2 stroke or what happens when mixed fuel goes through a carburetor.
    That is funny...Sort of like the poster that stated Merc Inlines run lean on oil on top cylinder due to gravity. Engines will not run on liquid fuel ..it has to be atomized in a gaseous state.
    Pappys Sales and Service
    Owner and Factory Certified Technician
    Former racer KDBA (Kentucky Drag Boat Association)

  11. #41
    Join Date
    Sep 2010
    Posts
    19,074

    Default Re: Cylinder bore question

    Wires on a VRO are for warning of a " No oil condition "-----I thought those pistons had low hours on them.-----Fact ----Most folks are unaware of how to test a warning horn or do a VRO consumption / output test.-----If a motor start and roars everything must be OK.

  12. #42
    Join Date
    Nov 2011
    Location
    tennessee
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    4,177

    Default Re: Cylinder bore question

    When he bought the boat a few years ago he was told the motor was rebuilt. It has standard 3.5" bore.
    Heres the red flags popping up..
    1) Was told it was rebuilt
    2) Bore is STD
    3) pistons look new
    I will say that that the cylinder that's damaged , rolled a ring and scored cylinder. Then someone did a backyard refresh(not rebuild) by honing and installing new pistons. Now its had a overheat occurrence and your stuck with it..
    Pappys Sales and Service
    Owner and Factory Certified Technician
    Former racer KDBA (Kentucky Drag Boat Association)

  13. #43
    Join Date
    Jun 2013
    Location
    Duluth Mn
    Posts
    2,643

    Default Re: Cylinder bore question

    I agree with Pappy. Perhaps you can find a nice block at Tim's Outboard in Hackensack MN. Typically outboards here in Northern MN are clean and lower hours. Great outlet for used parts. Talk with Mike or Dan 218 682 2331. If your committed to your bore or sleeve job, you will likely spend more money and time.

  14. #44

    Default Re: Cylinder bore question

    Timguy... thanks for that contact. There are no marine salvage outfits in Sacramento anymore. There is one about an hour south but they don't have a block. I don't want to get one from the Bay Area as most of those are used in saltwater. If my machinist says the block will need a sleeve then I will begin a search nationwide starting with Tim's Outboard.

  15. #45
    Join Date
    Jun 2013
    Location
    Duluth Mn
    Posts
    2,643

    Default Re: Cylinder bore question

    Okay, good. This is a friendly and expertly operated family business for going on 60 years. Those who have shared business with Tim's most often give extremely high praise. I would never steer you wrong. Twin Cities Outboard in Minneapolis/St. Paul is a bigger operation, but not my first choice. Minnesota is the "Land of 10,000 Lakes", our boating season lasts barely 6 months, so we are abundant with quality outboard parts.
    Last edited by timguy; 03-31-2020 at 01:47 PM.

  16. #46

    Default Re: Cylinder bore question

    Here is piston #1, the only piston with no damage. At 1/4" from bottom of skirt it measures 3.495 parallel to the wrist pin and 3.491 perpendicular to WP.
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  17. #47

    Default Re: Cylinder bore question

    Piston 2....
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  18. #48

    Default Re: Cylinder bore question

    Piston 3...
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  19. #49

    Default Re: Cylinder bore question

    So far, #2 and 3 look like hammered dog ****.

  20. #50
    Join Date
    Nov 2011
    Location
    tennessee
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    4,177

    Default Re: Cylinder bore question

    Rings rolled due to carbon build up...chitty oil or to cold..Does piston#2 have a number etched on crown ???
    Pappys Sales and Service
    Owner and Factory Certified Technician
    Former racer KDBA (Kentucky Drag Boat Association)

  21. #51

    Default Re: Cylinder bore question

    Quote Originally Posted by faztbullet View Post
    Rings rolled due to carbon build up...chitty oil or to cold..Does piston#2 have a number etched on crown ???
    What do you think about the possibility that the end gaps weren't checked?

    This would go in line with a crappy rebuild.

  22. #52
    Join Date
    Jun 2013
    Location
    Duluth Mn
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    Default Re: Cylinder bore question

    No way. That wasn't the cause. She got hot and lack of lubrication. Perhaps the same problem surfaced after the backyard overhaul.

  23. #53

    Default Re: Cylinder bore question

    Quote Originally Posted by faztbullet View Post
    Rings rolled due to carbon build up...chitty oil or to cold..Does piston#2 have a number etched on crown ???
    I can not find any numbers etched on any of the piston crowns. The only numbers evident are cast underneath...328 355 and 43003A

  24. #54

    Default Re: Cylinder bore question

    The #1 cylinder has no damage while 2 and 3 suffered badly.

    Do the OMC V4's have uneven manifold distribution or get less coolant where cylinders 2 and 3 run hotter? Interesting that the three pistons got that hot while #1 was pretty much unscathed.

    All four spark plugs are dark chocolate brown with no aluminum deposits evident on the electrodes.

  25. #55
    Join Date
    Sep 2010
    Posts
    19,074

    Default Re: Cylinder bore question

    The #2 is top on port and #3 is bottom on [email protected] different thermostat / poppit valves in the picture.-----Were the head gaskets on correctly , yes , no , not sure ?

  26. #56

    Default Re: Cylinder bore question

    Quote Originally Posted by racerone View Post
    The #2 is top on port and #3 is bottom on s[email protected] different thermostat / poppit valves in the picture.-----Were the head gaskets on correctly , yes , no , not sure ?
    The gasket is still stuck to the port side cylinder head, picture attached. Keep in mind that will I have built and rebuilt many types of engines, both 2 and 4 stroke with good results but I have no previous experience with outboards.

    The factory manual says "install head gasket per instructions on gasket" but does not offer any pictures. In the attached picture you will see the port head gasket says "Cover" with a directional arrow. If the arrow should be pointing towards the engine cover then the gasket is mounted incorrectly and I can see how coolant flow would be affected. The gasket on the starboard side is off and I did not notice how it was installed but if the port side gasket is wrong there is a pretty good chance the starboard side is wrong too.

    What's the verdict...is the gasket on the wrong way and if so would it have likely caused the problem?
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

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  27. #57
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    Sep 2010
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    Default Re: Cylinder bore question

    The one on the left was installed correctly.

  28. #58

    Default Re: Cylinder bore question

    Quote Originally Posted by racerone View Post
    The one on the left was installed correctly.

    Thanks racerone. So if the arrow supposed be pointing to the center of the motor when the gasket is on the block what is the word Cover referring to?

  29. #59
    Join Date
    Sep 2010
    Posts
    19,074

    Default Re: Cylinder bore question

    A new gasket would have all the words for you to read and heed.

  30. #60

    Default Re: Cylinder bore question

    Quote Originally Posted by racerone View Post
    A new gasket would have all the words for you to read and heed.
    Cook, thanks

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