Honda Mini HK1 4-Speed

Discussion in 'Some Assembly Required' started by Fast Idle, Nov 11, 2017.

  1. GR0NK

    GR0NK Got some screws loose!

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    Slow down, it's almost done!
    I was going to suggest running a Chinese motor crank (1P39FMB code) so that you could run CDI and not worry about points but I see you got a new crank. Well there are slip-on adapters to fit A CDI flywheel to a points crank... I get the impression you wasnt it as original as possible though. :wink:

    Those split rims are killer but I have found that a zip-gun usually makes quick work of moving the tire bead.

    20171028_173805.jpg

    I just finished Frankensteining a CT70 together using a pitbike front end (for the brakes) and a Chinese 4 speed semi-auto 90cc motor. I also jacked the rear end up with 400mm XL185 shocks.
    It's just a beater though.

    20171105_162851.jpg

    Looking forward to see a "proper" build.



    Sean :D
    #21
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  2. r60man

    r60man Long timer

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    I have zero experience with the split rims on these, and I am confused by what I am seeing. Do the two rings bolt together with the bead sandwiched inside?
    #22
  3. kevlar930

    kevlar930 Been here awhile

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    Fast Idle, I really enjoy following your build reports. One of my dreams is to find one of these and fix it up, so I will be taking extra notes on this one!
    #23
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  4. GR0NK

    GR0NK Got some screws loose!

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    Yes that's exactly it.
    Most of these bikes have never been used enough to warrant new tires. The result is a very old tire that is very attached to the rim halves and won't let go. If you don't have a tire machine it can be a very frustrating experience. :dirtdog



    Sean :brow
    #24
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  5. Fast Idle

    Fast Idle Since the Sixties

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    I know, it's moving along fast but I can't help myself.:evil
    Thanks for the heads up on the CDI adaptor. That might be an option down the road. It's been like 35 years since I worked on one of these little bikes. Still had my flywheel puller and clutch nut socket in the tool box from back in the day! I would like to keep it mostly Honda but it will definitely be getting some Chinese parts. Staying all Honda can get spendy. It also seems the HK1 model has some parts that are harder to find either as a good used part or in a re-pop. I know they are out there if I just keep looking.
    :beer
    #25
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  6. Fast Idle

    Fast Idle Since the Sixties

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    The rest of the engine parts made it along with a new chain and sprockets. The original Honda top end was in pretty tough shape so I went with the all new and affordable clone kit.
    DSC00070.JPG
    #26
  7. GR0NK

    GR0NK Got some screws loose!

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    Is that a new oil pump in the zip-lock bag next to the timing set? :thumb

    Always a good idea to replace it when you're rebuilding a motor that has been run low on oil. :deal





    Sean :D
    #27
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  8. ArdenLoneWolf

    ArdenLoneWolf Adventurer

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    Thanks for posting the build, I also picked up a CT70H that will be my winter project and I'm really interested in the engine rebuild process and parts list.

    Attached Files:

    #28
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  9. Fast Idle

    Fast Idle Since the Sixties

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    Yes, new pump, new top end, and new cam chain kit including the oil pump drive gear. Also new clutch plates and of course the oil screen and the correct drain plug!
    The case was molested by the 1/2" home made plug.
    p2 (9).JPG
    So I plumbed it up with some blocks and clamps to get it drilled for a heli-coil.
    p2 (7).JPG
    And then used the drill press to insure the tap started straight by hand turning the chuck with the key and some down force on the press.
    p2 (2).JPG
    Just need to do the final cleaning on the cases now that the heli-coil is done and it can start going back together. Everything else checks out good.
    p2 (1).JPG
    #29
  10. Fast Idle

    Fast Idle Since the Sixties

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    Cool, they are fun bikes! The only special tools you'll need to rebuild your engine other than a hand held impact screw driver are these and they aren't expensive.
    A flywheel puller
    08-0026.jpg
    And a spanner socket for the clutch.
    MP080015.jpg
    #30
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  11. Dr Klaun

    Dr Klaun Been here awhile

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    I'll be following this too!

    I have a 1970 that I just picked up for the kids that needs the full meal deal as well. The engine on mine has been cobbed together from the original block then with a Chinese top end from a quad with the knock off engine... Are any of the repro engines worth it (Chinese or other) or should I hold out to find a rebuilt ($$$) Honda unit?
    #31
  12. GR0NK

    GR0NK Got some screws loose!

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    The Chonda motors are actually really good. In my experience they are more reliable (CDI vs points and 12v electrics) and often they are better built. The design has been taken to 20+ HP in some cases (Daytona Anima). You can get them with e-start or your choice of semi-auto or full manual transmissions.
    It's not something a collector or a purist wants to see but if you just want to get an old beater running...
    Also, it's hard to complain about a 16hp YX140 for $450 delivered. (usually cheaper actually)


    Sean :thumb
    #32
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  13. Nemosengineer

    Nemosengineer Hair Ball

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    Hi Fast Idle,
    What media are you using in your sandblaster? Your cases look great!!!

    : Mike
    #33
  14. Fast Idle

    Fast Idle Since the Sixties

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    Hey Mike, I've been using these @ 65PSI
    DSC00072.JPG
    The Triumph cases turn out really nice.
    motor (2).JPG
    #34
  15. villageidiot

    villageidiot Long timer

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    I run AC glass beads at work.

    My favorite finish is AC beads I think the regulator on the blast cab at the shop is 40psi, and then I take em to the tumbler at my buddies shop down the street.

    I have to do some this week, I'll post a photo.
    #35
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  16. Nemosengineer

    Nemosengineer Hair Ball

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    The Triumph cases turned out really really nice, it's a great finish and texture. Thanks for the photos and information, I have a compressor that is underutilized so I'm shopping around for the right blast cabinet, its nice to know the glass beeds work so well at that pressure as the compressor should be able to maintain it. Now I need to find a nice Triumph sticker for the compressor.

    [​IMG]

    : Mike
    #36
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  17. Fast Idle

    Fast Idle Since the Sixties

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    Cool, never tried AC so it would be nice to see some photos. What kind of tumbler, like to see a photo of that too!
    #37
  18. villageidiot

    villageidiot Long timer

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    AC Is a pretty fine bead, not much different than AD.

    As for the tumbler. It's an old, noisy piece of equipment. If I can get some time tomorrow to work on personal shit, I should be able to have some photos in a coupla days.
    #38
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  19. Fast Idle

    Fast Idle Since the Sixties

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    :thumb
    FYI, I use my blast cabinet a lot. Could not get by without one, worth the investment for sure. I've had various media in it but pretty much settled on the glass beads. I have access to cabinets with granite when I need to sand blast something and I do all my soda blasting outdoors with a simple hopper and gun. It's what works for me. I made my cabinet years ago and it works just fine but I need to retrofit it with a spring loaded dump on the bottom for quick changing the media. The media wears out and gets dirty so it's nice to put in fresh bead when doing cases and such. The cabinet doesn't need a lot of media in it, just enough to always have a supply at the suction. I use a shop vac with the yellow drywall bags.
    #39
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  20. sealsam

    sealsam Sam...I am.

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    I'd like to see that too.:lurk
    #40
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