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Project FZR fix up

Discussion in 'Your 250cc Projects' started by Yetiburger, Oct 7, 2017.

  1. Andych

    Andych Senior Member Premium Member

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    As above... but if they were with a cold engine it isnt too bad... hard to diagnose much just on a compression test.. You are better off trying a leak down test and that will tell you if it is rings, head gasket or valves / valve seals.
     
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  2. Yetiburger

    Yetiburger Well-Known Member Premium Member

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    Yes the carbs were removed. how does one perform a leak down test?
     
  3. my67xr

    my67xr Bike Enthusiast Staff Member Premium Member Contributing Member

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  4. Yetiburger

    Yetiburger Well-Known Member Premium Member

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    ok so I performed a leak down test (maybe).
    I had a lot of trouble using the leak down tester and I really don't trust the results as I couldn't seem to set the tester consistently.

    It did show that cylinder #2 has a leak around the exhaust valve and slight Crank Case (CC) blow by.

    The results from the leak down test were weird and contradictory to the compression test.

    #1 23% in the green on the tester, no obvious leaks
    #2 50% leaks out of the exhaust pipe and CC
    #3 45% only a very slight CC leak detectable
    #4 25% maybe a very slight CC leak

    Do these results make sense given the compression test?

    Does anyone have any tips on using a leak down tester?
     
  5. Andych

    Andych Senior Member Premium Member

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  6. Yetiburger

    Yetiburger Well-Known Member Premium Member

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    ok guys can anyone confirm valve clearance?
    EX = 0.21 - 0.30 mm
    In = 0.11 - 0.20 mm

    And from the compression test and leak down test results is this motor stuffed?
    leak down test would zero but would not return to zero after the cylinder test.
     
  7. my67xr

    my67xr Bike Enthusiast Staff Member Premium Member Contributing Member

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    Clearance's are correct
     
  8. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    Stuffed? Having to fit new rings to a 30 year old motorcycle does not really qualify as stuffed. I would call that a service. :)
     
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  9. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

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    Those tests conflict, the best performance on the leakdown was the worst on compression

    You could try some threebond engine conditioner down the plug holes and past the valves to remove carbon, you would obviously need to drain the oil afterwards.

    Watched the video you posted of it running way back near the beginning of the thread, it was doing superbly given that it was running without the airbox.

    I think it may need a good run more than anything, you've been through the carbs, coil replaced, plugs were a problem for you at one stage - if you have one cylinder not firing consistently, the carb to cylinder head boots could be loose and leaking air, if you've removed them at any stage, another forum user was spinning in circles with a lot of what you've been through, turned out to be that, or they could be cracked

    I say get on it and ride it, get the idle circuit tuning done with the engine up to temp
     

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