4 speed manual clutch motor z50

Discussion in 'Tech Area' started by Marcus, May 10, 2021.

  1. Marcus

    Marcus Member

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    What if any modifications need to be done?
     
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  3. lukelaw1

    lukelaw1 Active Member

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    need some more information. are you taking a stock 3 speed z50 motor and converting to a manual clutch 4 speed? or aftermarket 4 speed?
     
  4. Marcus

    Marcus Member

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    I was just thinking about putting a ct70 motor in it..aren't they 4 speeds with a hand clutch? I took the z50 for a long ride today and it got really hot and quit running..do you think I damaged anything? Or are they pretty durable. Also what is the correct needle position and fuel/air screw setting?
     
  5. OLD CT

    OLD CT Well-Known Member

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    It's not good to take a fresh rebuild for a long ''first'' ride. It should be taken out for 15 minute short rides and cooled off. Now you need to take it out for a 15 minute ride, come home and dump the oil and put fresh 4 stroke M/C oil in. Ride it easy don't run it full throttle just yet. Change the oil frequently! You are going to see a lot of fine metal in the oil, don't panic. You have to change it often in the beginning. 4 speed CT70 engines are not easy to find, and if you do they are going to run you some big bucks.. $1000.00+ easy, if it's rebuilt already.

    If you are buying a used core engine it will cost around 800 bucks in parts, plus whatever you pay for the piece of crap. Consider buying a ''basic'' 88cc kit, that's close to $150 and a $150 4 speed AHP transmission + a $165 trailbikes 4 speed manual conversion kit. That's $465.00 worth of shit right there to add on to all the money you already dumped in to it. Don't buy someone else's used headache. Build your engine up.
     
    #4 OLD CT, May 10, 2021
    Last edited: May 10, 2021
  6. Marcus

    Marcus Member

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    Damn ok..it wasn't the first ride. I rode it three times prior to tonight for about 10 minutes all three times..do I still have to do 15 minutes? Do you think the engine is ok since I overheated it?
     
  7. OLD CT

    OLD CT Well-Known Member

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    Yes! Short rides keep it cool till it breaks in, and frequent oil changes get the fine metal shavings out.
    No long rides yet. Is it ok? I hope so...:eek:
     
  8. Marcus

    Marcus Member

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    Ok cool thank god it's ok..ok I'll do the oil changes I'll change it before the next ride..what is the correct needle position and air fuel screw setting?
     
  9. OLD CT

    OLD CT Well-Known Member

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    Didn't you just put 2 brand new Honda 3 speed shift forks in that engine? I wouldn't want to take them out and have 100 bucks + shipping, laying on the shelf... Enjoy it as is for a while.

    There is no exact setting, it depends on what the plug looks like and how it runs. I do however like to tune the carb with ''jetting'' to run good with the clip in the middle. The A/F setting in a book is just a starting point!
    You have to warm the engine with that book setting turn the idle down real good to ''hear the change'' then turn the A/F screw slowly in either direction till you achieve the highest smoothest idle, then turn it 1/4 clockwise. P.S. I don't own any Z50's but understand basic carb tuning. You may need to re jet a little, not sure yet. Try 1 1/2 turns out from ''lightly seated'' for a starting point only. If you ''crank'' the A/F screw 'in'' too tight you could damage it internally.
     
    #8 OLD CT, May 10, 2021
    Last edited: May 10, 2021
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  10. Marcus

    Marcus Member

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    Ok I will just enjoy it like u said..I wasn't gunna do the 4 speed deal just yet anyway...
     
  11. Marcus

    Marcus Member

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    I didnt see the second part of that last post..my bad
     
  12. cjpayne

    cjpayne Well-Known Member

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    Manual says to set the valves at .002in and .002ex. Set the exhaust at .003. It will run a little cooler. On a K1 engine I had, it made all the difference in the world on the temps.
     
  13. Gary

    Gary Well-Known Member

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    The problem with a 4 speed clutch on a 69 is what to do with the rear brake after you lose the rear brake lever when it becomes the clutch. A k2 with a brake pedal makes it so much easier.
     
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  14. Marcus

    Marcus Member

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    Cool sounds good I'll set the valves to those specs..that's what I was just thinking gary.
     

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