Compression testing engine.



  • Could be a simple answer to this but ive never actually done this before!!.

    I want to do a compression test to guage the condition of my Ze.
    Q1, anyone know the readings that should be obtained?
    Q2. I assume its as simple as take out each spark at a time, plug in compression guage, unplug dizzy to stop spark, pull fuel pump fuse to stop fuel. This should stop engine from being flooded while testing ?

    Theres prob a youtube video on this or a link on mx3.com but thought id be lazy first !. Im sure other memebers may be interested in this also.



  • quick google looks like im right apart from have to remove all plugs not one by one ?, not sure what difference this would make, also i need to run engine and then let it cool.

    should be a consistant 200-225 psi. More so towards 225 for a ze and low 200 for a DE.

    will be doing it over the weekend so will post results :mrgreen:



  • Keep the TB butterfly open as well.
    Remove all the spark plugs

    Healthy ZE is 210-220
    DE 190-200

    Still oke engine; 160

    Crap 120-130 (like mine) won't run anymore.



  • Cheers mate, I forgot about the wot part too!.



  • Well results are in; bit 2 ways really, part of me is disspointed, but other part of me is happy because engine can be rebuilt so i know exactely whats going on inside. As the original engine came from japan, sat on a pallet for about 3 years and then got fitted, ive never really known the history or condition as ive not opened it up, only put on a cambelt and water pump and dropped it straight in.

    Anyhow, i tried it twice, 2nd time i really let engine get a good long run before testing but the readings remained the same.

    Top left bank 145
    Top middle bank 160
    Top right bank 145
    Bottom left bank 130
    Bottom middle bank 140
    Bottom right bank 135

    So next quest is what parts to fit now engine is coming out, I have KLDE valve springs and retainers, thinking about colt cams, cam belt, water pump, head gasket, a good port and polish.

    any more suggestions ??? or reasons why readings could be low?.


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