Honda CT70H Stator Parts

Discussion in 'Tech Area' started by 42653steve, Oct 4, 2019.

  1. 42653steve

    42653steve Member

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    Thanks For the info. Hopefully I get a chance tomorrow to check everything out.
     
  2. kirrbby

    kirrbby Well-Known Member

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    I have thought about how to build a coil winding jig for our bikes before...6v type. I think I could build something that would work pretty well, and make that job easier, and neat. It would of course be pretty primitive, made of wood and steel...with a crank handle.

    It seems like I've seen one somewhere before...online. It was a powered setup that had a foot pedal, like moms sewing machine. The foot pedal was to spin the coil, slowly, so you had both hands free to guide the wire.
     
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  3. Gary

    Gary Well-Known Member

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    I did not pull anything apart but here are some observations- I have a Frankenmotor using a S65 internals with a CT 3 speed crank and cases,cylinder and head. It is also using a Hitachi flywheel and the S65 Denso stator. The S65 used an advance Denso flywheel so how does that work?? I'll take it apart in the future to check it out but I'm wondering- Denso was founded by Toyota and today owns 25% of it, you don't see many Denso products on Hondas was there a conflict/falling out when Honda started building cars?
     
  4. allenp42

    allenp42 Well-Known Member

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  5. allenp42

    allenp42 Well-Known Member

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    Would like to see your ideas. Sometimes, I'm lacking in creative skills or get stuck over complicating things.

    Of the few that I've wound, I put the spool of wire in a rod that that was sized to make the reel a little hard to spin. Turned the coil in my hands trying to maintain reasonably tight windings on the coil. Seems to work but a better mouse trap would make it easier.

    Never had a denso stator or flywheel or seen many pics of them either. Maybe I'll snag one this winter and take a peek. I think that some of the 80-82's CT70s are Denso but not sure.
     
  6. racerx

    racerx Administrator
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    You both have great ideas. There's a practical element here that makes creating a mechanical armature winding machine impractical...complexity and that translates in dollars, too many of them. Best method available, at present, is meticulous winding by hand. When the established shops out there are doing this, the logistical reality of the situation is clear.

    IMHO, investing an hour painstakingly rewinding a lighting coil isn't a big deal, as long as the results are there at the end. It only has to be done once. And, with lighting coils, as long as you have sourced the correct wire size (gauge) there's enough latitude for "close enough"...seriously. I think we're losing sight of the bigger priority...that there's a viable and inexpensive way to restore a rare coil.
     
  7. allenp42

    allenp42 Well-Known Member

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    Spot on as always. You can safely remove a few turns from the primary coil or lighting coils and never even notice it. Unless a coil is damaged through more than 1 layer, I would not hesitate to remove a few turns until I got beyond the break and solder it back into the circuit.
     
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  8. racerx

    racerx Administrator
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    Same here...I like clean solutions and the best ones tend to be so, uncomplicated too.
     
  9. kirrbby

    kirrbby Well-Known Member

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    I'm a pretty pathetic artist. 2 dimensions I'm ok, 3...not so much.
    I could probably just build it, easier than I could draw it...after I get back to my 2nd home.
    I'll build 2. One for you...one to keep. Then you could improve and modify it as needed.
    I was planning to have provisions for some friction resistance on the spool, and on the crank for the coil too. I expect it would all fit on a 8"x10" piece of plywood. But I'm not sure what kind of spool...sizes...coil winding wire comes spooled on. Might need some guidance there, or a recommendation of what to buy.
    Probably best for me to just buy a spool to use.
     
  10. allenp42

    allenp42 Well-Known Member

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  11. kirrbby

    kirrbby Well-Known Member

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    Oh ya, I don't miss much on lh.
    Don't be in any hurry. I'll build them at work, and it's looking like 3 weeks+ before we get back.
    Are the spool sizes standardized? Both spools you mentioned have the same ID OD?
    Would probably be reasonably easy to put a counter on them too...to count revolutions.
    Could maybe pick up a cheap Chinese counter for $1 ...shipped! :)
     
  12. racerx

    racerx Administrator
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    Counting the number of turns is one method but, the most accurate method for replicating any specific configuration is the measure wire length. That'll insure the exact coil impedance.

    When winding a radial array, each coil should be wound exactly the same way, i.e. how the turns of wire ate laid-down, sequentially. Think in terms of a helix, with each layer of windings resembling fine bolt threads...perfectly even spacing with each subsequent layer fitting like a thread guage. It's impossible to be that precise, without a CNC machine...but it's the ideal and a good goal.

    The only coils I've seen that were wound that uniformly are all single coils. The 5 & 6 coil radial array stator coils never appear this neatly wound.
     
  13. allenp42

    allenp42 Well-Known Member

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    Somewhere in my notes, I have the ft of wire for each layer for a given wire size (diameter). As you know, the ft of wire used increases on each successive layer. I even unwound one coil and measured it to make sure my calcs were close. When I get back into it sometime this fall/winter, I'll dig it out.

    But for sure, it gets more tedious to maintain a "cosmetically appealing" wrap after about layer 3.
     
  14. Gary

    Gary Well-Known Member

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    Check out the wrappings on here - http://www.genebitsystems.com/david/CustomRewind/index.htm and you will see they are not perfect either,interesting to see the gauge wire being used as well. After they are coated like in the first picture you don't notice the wrapping anyway and once mounted on their plate and under the flywheel no one will know.....
     
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  15. allenp42

    allenp42 Well-Known Member

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    Oh yeah. Multi coil and probably configured as 3 phase. I also noticed he powder coats the laminations vs. a using paper wrap. Just a guess, the wire is at least 18 ga. Can get some real juice out of that stator.

    In the case of a single coil as used on Z50s, CT70s, etc. It's a compromise. One coil and 2 sets of magnets and there is some "sharing" of the magnets with the Primary coil is what we have to work with unless one choses to go with a 12v crank, stator and flywheel.

    Smaller wire allows for more turns which provides more voltage but less available current at higher RPMS. Net net - limited power at higher RPMS. Larger wire = less turns but lower voltage and higher current. There is a sweet spot for sure, and I think my next attempt this winter will find it. I have several wire sizes in a box, some test data on various wire sizes and turns, but there is one more gauge I want to try.

    I read somewhere that most automotive alternators are designed to power all accessories and keep the battery charged when the engine is at idle. For sure, that is not an option here.
     
  16. racerx

    racerx Administrator
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    With an automotive application, a 140a alternator can put out ~1680w @12V that's just over 2hp. It's unnoticeable with hp & torque numbers in 3 digits. I doubt that any small displacement single cylinder bike engine could be started while spinning that much alternator.

    As for neat, uniform, precise windings, it's nothing to do with aesthetics and everything to do with getting every last watt squozed out of that tiny alternator...because there aren't many of them. In point of fact, even the OEM Honda radial array stator coils look pretty crudely wound...they're fugly. They also ate capable of producing 70w which is very useful.

    Anyone remember Markus? He adapted a 140w Ducati alternator for a tuned Nice engine. That's enough juice to power damn near anything you could carry on a bike this size. IMHO that was way over the top but an interesting example/concept of what is possible...at the extreme.

    Back here in the real world of highly skilled shadetree engineers, we're looking for at least 30w of DC power, from existing stator armatures and flywheels...pushing the design(s) close to their physical limitations. If a little extra painstaking attention to detail can make a measurable difference...it's a free upgrade, when they aren't many other possibilities.
     
  17. allenp42

    allenp42 Well-Known Member

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    30 watts is obtainable with the current stator design. RPM plays in the picture so I just need to do a power curve and let everyone take a look to make sure that it's practical. "Painstaking detail"...is where I left off last winter and want to go this winter on a 12v wound coil. I have seen enough that a little more is possible...and I want to determine the "little more".
     

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