Welcome Guest - Sign Up today
Welcome Guest - Sign Up today

Announcement

Collapse
No announcement yet.

Rich oil mixture and poor compression ratios on 75hp 2-stroke Suzuki?

Collapse
X
  • Filter
  • Time
  • Show
Clear All
new posts

  • Rich oil mixture and poor compression ratios on 75hp 2-stroke Suzuki?

    Hi,

    I am considering buying a boat with an 80's era 2-stroke 75 hp Suzuki, but am concerned about low compression ratios on one cylinder: #1 = 128, #2 = 138 and #3 = 140.

    I spoke to a mechanic about this and he told me that a likely cause may be an overly rich oil mixture. As it turns out, the seller was running a double rich mixture because he was concerned about his oil pump giving out, so he pre-mixed his fuel as well.

    I'd like to know if anyone has any thoughts on this before committing to a purchase? Perhaps I should have a second test done while the engine is running on a leaner mixture?

    Thanks.

  • #2
    Re: Rich oil mixture and poor compression ratios on 75hp 2-stroke Suzuki?

    [QUOTE=SwillFish;4018286]Hi,

    I am considering buying a boat with an 80's era 2-stroke 75 hp Suzuki, but am concerned about low compression ratios on one cylinder: #1 = 128, #2 = 138 and #3 = 140.

    I spoke to a mechanic about this and he told me that a likely cause may be an overly rich oil mixture. As it turns out, the seller was running a double rich mixture because he was concerned about his oil pump giving out, so he pre-mixed his fuel as well.

    I'd like to know if anyone has any thoughts on this before committing to a purchase? Perhaps I should have a second test done while the engine is running on a leaner mixture?

    The compression numbers sound just fine to me...within about 10% of each other. But if that "seller" has been running the premix And the oil injection all these years(mid 80's), maybe carbon on piston crowns, combustion chambers, piston rings/grooves?....Maybe look in through each spark plug hole with a bore scope to see about heavy carbon?

    Comment


    • #3
      Re: Rich oil mixture and poor compression ratios on 75hp 2-stroke Suzuki?

      Thanks Robert. The seller just started doing this recently when he was worried that the pump was failing.

      My mechanic recommends a product called "Carb Clear" (I think?) to remove long term deposits. He says it works really well.

      Comment


      • #4
        Re: Rich oil mixture and poor compression ratios on 75hp 2-stroke Suzuki?

        Originally posted by SwillFish View Post
        Thanks Robert. The seller just started doing this recently when he was worried that the pump was failing.

        My mechanic recommends a product called "Carb Clear" (I think?) to remove long term deposits. He says it works really well.
        "Just started doing this recently" is O.K., but why is he "worried that oil pump was failing"? If you're not confident of oil pump system then maybe check it out and replace if required? Most outboard motor oiling systems are very reliable, given good maintenance. Lots of "carbon Removers" on the market, but the Yamaha Ringfree is a widely used product and respected....Made by Oronite Additives of Chevron, similar to automotive Techron.

        Comment


        • #5
          Re: Rich oil mixture and poor compression ratios on 75hp 2-stroke Suzuki?

          Thanks again Robert.

          He was worried about the pump failing because he saw a bubble in the oil line. Apparently it's working fine.

          I will use a card remover. Every mechanic I have spoken to has warned me about the damage the newer ethanol based gasoline can do to engines with it.

          Comment


          • #6
            Sign up today
            Re: Rich oil mixture and poor compression ratios on 75hp 2-stroke Suzuki?

            Maybe start using a Fuel Stabilizer like Stabil or Seafoam all the time, and install a Walmart/Attwood Fuel/Water Separator($27)...easy to install and can save you a lot of fuel-related problems. The Yamaha Ringfree is a seperate item primarily just for carbon control and can be used in addition to the Stabilizer....I use these at recommended dosages and never had any fuel/carb problems at all, since I purchased motor new in 1999...Not much doubt that preventive maintenance is much cheaper than repairs! Good Luck!

            Comment

            Working...
            X