Compression Testing
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  1. #1
    PWCToday Newbie
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    Compression Testing

    So before anything, I will say I have checked to make sure I am doing this the right way. I believe I am.

    I am trying to check the compression on my 2 stroke but something is odd....

    I took out cylinder ones spark plug and screwed in the gauge adapter. I had the other spark plug caps on the ground terminals. Cranked her over, gauge stopped reading at an even 100psi.

    Checked cylinder 2 was exactly the same.
    Cylinder 3 is where it gets odd. The needle on the gauge didn’t move at all for a good 5 seconds. Than it did and only read 30 psi.

    i thought maybe I was doing it wrong so I rechecked cylinder 2. This time cylinder 2 only read 35 psi. I checked to make sure the gauge was tight in the cylinder head, which it was.

    WTH is going on? Lol.

    All 3 cylinders fire and run on their own. I disconnected and left one spark plug cap on each plug to test if any of them were dead.

    Am am I doing something wrong or is this $20 gauge I got just a POS?

    Also, is there a minimum amount of cylinder pressure in order for a cylinder to fire? The fact that each cylinder runs on its own, and runs good and strong makes me think either my gauge is messed up or I’m messing this up. The only reason why I wanted to check the compression was for my own curiosity. Supposedly the motor was rebuilt 3 years ago, which I have paper work. They wrote on the cylinder head the pressures of each cylinder too. (Which I guess could all be a lie if someone had there buddy write up a fake receipt)

    Notes: Only smokes at startup, typical 2 stroke. Spark plugs are always clean and never cooked. Sounds strong, fires right up cold or hot. No issues as far as the motor.
    Last edited by Pj96; 07-02-2019 at 03:33 PM.

  2. #2
    PWCToday Newbie
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    Re: Compression Testing

    DEBUNKED


    Don’t buy cheap compression testers

  3. #3
    Attention ***** PWCToday.com Is My Home Away From Home JonnyX2's Avatar
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    Re: Compression Testing

    That is great advice
    Quote Originally Posted by Firebird A/C&Heating View Post
    OMG.....Rules for 550 vintage ski class...550 ski riders do not conform to any kind of rules. That is why you are riding a 550 ski in the first place. Rules suck....
    PS...the rule book will be in my 550 pump
    Quote Originally Posted by WB1994
    Listen , stop your cryin' , its only an X2.

  4. #4
    I dream skis needforspeed's Avatar
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    Re: Compression Testing

    I have a compression tester and had a similar experience ...I rebuilt my wave raider 1100 top end. after I wanted a baseline so I tested all three holes and got 90 psi..I thought it was low for a fresh rebuild and waited to get some hours on it and after everything was seated correctly took it again..90 psi...I said to myself "self, that is low" but the thing ran like a raped ape so I didn't worry about it. Then I was working on my Yamaha 650 engine and I got 90 psi both holes..Didn't really think much about it..again it ran perfectly.. a couple seasons later (this spring) I got a free 89 Kawasaki 650 sx..I wanted to know the condition of the top end so I do a compression test...low and behold 90 psi both holes.... something aint right here...So I look closer at my tester..The "glass" covering the gauge is really a plastic lens. I keep the tester in my trailer toolbox. It must have gotten too hot in there because the lens for the gauge melted inward and the needle would always get stuck at 90psi. I took the plastic lense off and she is much closer now and I get more believable so my 89 sx that was getting 90 psi in each hole now gets 185 in each hole....I'm thinking it is an aftermarket head because of the higher compression and it doesn't say Kawasaki anywhere on it but it has no other marking on it either....anyway a good tester is the way to go. I bought mine at sears years ago it is not a craftsman...I am due for a new one...
    Last edited by needforspeed; 07-11-2019 at 08:47 AM.
    If it aint broke...don't fix it!!!!

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