H74 PART 2 - tweaking & tuning the desktop vintage 4 cylinder model engine 4 stroke Chinese Holt

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  • Опубликовано: 20 окт 2024

Комментарии • 16

  • @simplefact4u
    @simplefact4u Год назад +3

    I have the same engine. The best way is to take the exhaust off and run all cylinders , because when you take a cylinder offline, you changing the fuel distribution . With exhaust off you can easily spot which one is running well or not. Touch wood mine works flawlessly. I changed the spark plugs to RCExl ones I got from aliexpress.
    I totally love this one. Sounds and revs epic. I can sit and watch the governor work for hours

    • @ThomasPCGuruENGINES
      @ThomasPCGuruENGINES  Год назад

      Yeah trying to avoid that but I think I just showed your option is the best! Thks Binnie

    • @simplefact4u
      @simplefact4u Год назад +1

      @Thomas PCGuru ENGINES yours running pretty good now though . It's a gas guzzler, but totally worth it

    • @charleslum2438
      @charleslum2438 Месяц назад

      I can't get enough of this while waiting for mine to arrive. It's somewhere on a boat headed this way. This is the video that made my mind up to get the H75. After seeing the governor at work I think it will serve the purpose I have in mind. I am not gonna sleep until it gets here.😂😂😂 At least I get to see and hear one run now,thanks.

  • @anythingoldmechanical
    @anythingoldmechanical Год назад +1

    Great job, Thomas.
    Well done!!

    • @ThomasPCGuruENGINES
      @ThomasPCGuruENGINES  Год назад +1

      Thank you Gary! Cheers!

    • @anythingoldmechanical
      @anythingoldmechanical Год назад

      @@ThomasPCGuruENGINES I'm praying that in the future you purchase an Eachine ET6, so we can all see how the flyball governor comes apart to shorten the spring, so it hit and misses correctly at a realistic speed! 🤞

    • @ThomasPCGuruENGINES
      @ThomasPCGuruENGINES  Год назад

      Noted Gary. Mission.

    • @ThomasPCGuruENGINES
      @ThomasPCGuruENGINES  Год назад

      ....and I can tell you now. Same governor as H73.
      disconnect the flyball base pins
      move those bases out so you can spin undo the top from the bottom! There's a spring in the top!
      You can see it disassembled! ruclips.net/video/EHKSrchDa5o/видео.html
      SHORTEN THAT SPRING SLIGHTLY
      watch my reassembly.
      as you'd suspect assembly is the reverse of disassembly...et vice versa ...et viola!

    • @anythingoldmechanical
      @anythingoldmechanical Год назад

      @@ThomasPCGuruENGINES I STILL cannot see how you lift it off to access the spring, so I'm still no wiser!

  • @Axeman428
    @Axeman428 Месяц назад +1

    I had weak compression on the first cylinder in my h75 that I just received a couple of days ago. I put the new rings in and washed the heads with solvent because I found a leaking valve. It must have had some trash or something between the valve and seat. It has good compression on all 4 and runs better now but still doesn’t run as it should. I think it’s an intake leak. Maybe the O rings between the intake and heads are not properly sealing, one of them anyway. I too noticed if you get a good tight valve lash it makes them come off the seat between cycles, camshaft base circle is not true like you say. It also has a bent crank. The flywheel/pulley has a little runout, not bad but I can see it. I will be taking it down again and try to straighten the crank. Have you had any experience with that. I don’t think it will be too hard but you never know till you try. A little insight would be appreciated. Senna like you got this one working pretty good. I had the same problem, #1 & #4 cylinders were dead. I got them up and going but it still idles a little rough and won’t run @ full throttle if tuned to idle and vise versa. I’m gonna check that intake next. I didn’t take it loose when I put the rings in it but I’m pretty sure it has an O ring out of place since I heard yours unless mine has a carb problem and there’s not much to go wrong with these little carbs. Good job on this one by the way.

    • @ThomasPCGuruENGINES
      @ThomasPCGuruENGINES  Месяц назад +1

      Mmmm I don't know where to start...they are tricky. Firstly the basics, you've covered them all...intake manifold casting isn't always ideal for the rings, remove and improve with a flat file if necessary. Oli valve stems. Check valve opening and closing timing. Usually valve timing and ignition timing make a huge difference in this engine so check. Tiny engines means set ignition closer or at TDC. Carb tuning is tricky but if you want to rev, it likes rich. Lastly, unless you like fiddling, check if you have got an issue beyond your inclination to fix. Crank is not necessarily bent, on an engine with a wobbly flywheel i bent it back in by hand. But once you get to engine tear-downs it might be worth asking for replacement or selling privately and replacing. Jus' sayin.

    • @Axeman428
      @Axeman428 Месяц назад +1

      @@ThomasPCGuruENGINES It was the front pulley that had a little runout. The crank is fine. The problem was the plug wires. I got those lined out and now I am disassembling it again to clean up the castings and seal all the oil leaks. It has many but it had no gaskets on the crankcase and they aren’t machined to fit perfectly as you know. It runs much better but the carb leaves much to be desired as you can’t tune it for low speed idle and high speed power simultaneously but it will idle smooth and slow now and as long as you don’t open the throttle up it does fine. Thanks for your time and videos.

    • @ThomasPCGuruENGINES
      @ThomasPCGuruENGINES  Месяц назад +1

      Thanks for your confirmation of the frustration I and others have with these carbs; succinctly, "can’t tune it for low speed idle and high speed power simultaneously but it will idle smooth and slow now and as long as you don’t open the throttle up it does fine" best at demo speed