1974 Z50 Hard Start

Discussion in 'Tech Area' started by Beretta, Nov 17, 2020.

  1. Beretta

    Beretta Member

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    So I have this 74 Z50 that's a PITA to start- Kicking it seems like the clutch is slipping. Pulled the Plug and performed a Compression Test--(125lbs)- I'd like to see that a little Higher.
    It's getting Gas--Spark is Good- Points are set--Plug is New and Adjusted the Clutch. When it finally does start it's the fastest Z I've ridden- after its warm it starts 1st kick all day,
    Q: Could the clutches be that worn ?
     
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  3. red69

    red69 Well-Known Member

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    If it were a clutch problem I would think it would be there all the time not just on the first start.
     
  4. hrc200x

    hrc200x Active Member

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    My experience with slipping clutches when trying to start is that it gets better when its warmed up. The easier or softer you can kick it when its doing its clutch slip thing the better the chances are of it turning the motor over and starting. As with everything 4 stroke, kick start or pull start, kick slowly till find the most compression, roll motor just past that then kick what's needed to start. Trying to pull start or kick start any 4 stroke through the compression stroke will be harder on starter parts than doing it the above mentioned way. Plates are probably wore or just old glazed cork and replacing would fix the issue, adjusting clutch might help but usually does not
     
  5. hrc200x

    hrc200x Active Member

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    Also wrong oil can cause plate slippage. Dont use automotive oil, needs to be motorcycle oil thats wet clutch compatible.
     
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  6. cjpayne

    cjpayne Well-Known Member

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    If it still has the original main clutch springs in it, they are probably weak too.
     
  7. Beretta

    Beretta Member

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    Thanks for the input- all of it helps. Not to debate Oil but I use Rotella T4-15/40- It has No Friction Modifiers which can cause Wet clutch issues.
    I'm going with a worn clutch and going to order parts today.
    I will measure the old plates and look for wear patterns as well
     
  8. kirrbby

    kirrbby Well-Known Member

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    This is a very very common problem with our bikes. Most often you just need to adjust the clutch preload, AND kick slower. New plates and springs can cure it completely...maybe. but you really just always need a slow kick.
    By the book clutch adjustment is NOT always the best adjustment. Your bike may need more preload, or less preload in order to kick AND shift properly.
     
  9. kirrbby

    kirrbby Well-Known Member

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    BTW...I have at least one bike that I can stand beside and start with my hand. The best engines will start on the first few sparks. If you're needing repeated kicks...maybe look into a fuel or ignition/timing problem.
     
  10. OLD CT

    OLD CT Well-Known Member

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    Rotella is fine Baretta, One thing Iwill mention is don't bother measuring the discs. They can look perfectly fine measure well within spec and still slip. Replace em and you will see the difference on the first kick.
     
  11. Beretta

    Beretta Member

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    Today I adjusted the Clutch again--3rd time- Still slow kicked like Mush- 4th Kick it Fired and Idled fine- Let it warm up and rode it for about a mile or so--Threw it up on the bench and I could Hand start it every time while it's warm-- Note My Shop is Heated @ 62 deg all winter- during the day it's 70 deg all day while I'm out there usually every day.
    Think I'm gonna replace the Disc and check things out- Problem is they aren't available from my 2 suppliers- DRATV nor CHP at the moment. IMG_4860.jpg
     
  12. CLEC66

    CLEC66 Member

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    Draft has them, just look in the ct70 engine category as their the same as z50 up to 1979 I believe.
     
  13. Beretta

    Beretta Member

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    Thanks ! Didn't know they were the same - I ordered them this am.
     

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