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  1. #1

    Compression is at 115 115 90. Alright or bad

    Just checked it and this is what I'm getting 100 to 115 on front and Center and back is at 90 to 92. I'm I safe or have a problem


  2. #2
    I just put oil in the one that was at 90 and it went to 130 and hold perfect. Do you still think I have a problem

  3. #3
    Click avatar for tech links/info, donation request K447's Avatar
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    Low compression usually indicates something is not quite right with the piston and cylinder. Piston rings worn or damaged, piston itself damaged, piston rod bearings damaged, cylinder wall scored or damaged.

    Unless you remove the cylinder head and actually inspect, it is mostly guesswork as to why the compression is low.

    Adding oil simply masks the problem by reducing air leakage past the piston rings during compression testing. The oil does not of course improve actual compression when the engine is running as the excess oil burns off quickly.

  4. #4
    Cool. So are you saying go in or leave it to see if there any big change

  5. #5
    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by travis ingram View Post
    Cool. So are you saying go in or leave it to see if there any big change
    If you do not inspect then you are simply gambling that whatever the problem cause is will not get worse or cause further damage.

    For example if the problem is a broken piston then there is a possibility of pieces becoming jammed and bending the connecting rod when the engine seizes while running.

    From here I cannot tell you what is wrong with your engine. If it was my own engine I would be taking it apart enough to inspect and determine the cause(s).

    BTW, it is always helpful to mention which year and model you are asking about.

  6. #6
    Oh it's a 2002 genesis 1200 carb. And you are right taking a look is not hard. I've all ready rebuild one engine, with SBT pistons big mistake one of them, the ring melted in the piston so I bought this engine so I've have two. Now the weard thing about that was that piston compression was good. But the back was at 110 or 90 like this engine. And when I took apart the frist engine the back piston was great. When I get a changes I will put pictures on hear to show.

  7. #7
    john zigler's Avatar
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    This is the beginning of the end of your motor.

    Be sure to determine what is causing your failures BEFORE you replace / rebuild or you will continue having troubles.

  8. #8
    Went out today and the low rpm was low fuel. plus old fuel and spark plus. So don't let anyone tell you can make your frist run. With out putting fresh gas and spark plus in. I always did but I was so jumpy I said one hour of riding wont be bad. But there it is.

  9. #9
    Oh I have a question. If one cylinder is bad and the other are not can I fix the one or do I have to do all three. All the other time I did all three but soon this polairs is going to be worth more then my house. Lol

  10. #10
    BlueFishCrisis's Avatar
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    You can do just one, but try to stick without upsize/oversizing it to replace.

    Replace the jug and piston with the same size to match....

    As always, figure out the source of the problem before swapping out the cylinder or you'll be back soon......

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