CT70K1 Rotor and Stator

Discussion in 'Tech Area' started by Dennis McDonaugh, Apr 12, 2020.

  1. Dennis McDonaugh

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    After kicking the bike over a few times, I started hearing snapping sounds from the rotor/stator area. The kind which is usually accompanied by a spark. I didn't have the correct flywheel puller so I had to wait a few days to investigate. The puller came in yesterday so I was able to look at it this morning.

    IMG_3129-L.jpg

    IMG_3130-L.jpg

    There's a lot of rust in there and there were several small pieces of rusty metal in the bottom of the rotor.I think they must have hit the coil on the right.

    I found the guts for the stator from CHP Motorsports for $35, but they won't have more for a couple weeks.

    I looked at a parts breakdown and it doesn't look like there is a gasket for the side cover to keep out moisture. Is that correct?

    Can I clean the inside of the rotor to remove those rust stains without damaging those embedded magnets?
     
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  3. racerx

    racerx Administrator
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    The primary coil looks a fright but photos don't always tell the whole story. I kinda doubt that you'd get arcing from a damaged primary coil, not enough voltage. Best educated guess, it takes ~10,000v to jump a plug gap. There's less than 100v coming from an intact primary coil. Can't say I blame you for throwing a stator rebuild kit at this. In your situation, I'd do the same thing; $35 is really cheap insurance + peace-of-mind.

    More likely that you were hearing the rust making contact. That flywheel, overall, looks pretty good. The point cam appears clean & shiny. If you have a die grinder & wire wheel, that'll make quick work of the rust. Bead blasting does a good job, too...just keep it away from the flywheel bore & point cam.

    Do replace the points & condenser. Those are the parts that have a finite service life and they'd have to be removed anyway to replace the coil.

    As for a flywheel cover gasket...at one time it was a common part, included with most gasket kits. Those went extinct around 2000. You could paint-on a thin coat of silcone RTV...oil pan gasket flavor...to the flywheel cover and points inspection cover. I would advise against that. The gasket was meant to keep water out of the stator, while riding through standing water, more so than keeping humidity & condensation at bay. If you seal the flywheel cover to the engine, you may get more water exposure from condensation. Plus, it's a friggen mess to deal with.
     
  4. hrc200x

    hrc200x Active Member

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    That rust looks better than some I've seen. I lightly sand the face of the coils and the magnets, but I'm not really sure you'd have to unless the rust feels rough. Thats correct, no gasket on the flywheel cover. on the motor side of the flywheel the center hub thing is like a cam, its what opens the points. This needs to free of rust and needs to be smooth, if its rough it will wear down the rub block on the points in no time. I'd try to run all the stock parts behind the flywheel except maybe the points, you can file, clean, and reset the gap on your points to maybe get you up and running. Can you put flywheel back on and tell where snap was coming from? The flywheel covers do have a drain to let water out, I've never understood why no gasket there but there is one on the points cover and atc70's do have a gasket in that place.
     
  5. racerx

    racerx Administrator
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    The answer is...drum roll please...product planning. The erstwhile gasket was an SL70 part, as I recall, that was a serious offroad specialist machine. The CT70 is a generalist, more Swiss Army knife than machete, excuse the horrible metaphor. What I'm saying is that water depth that might challenge an SL70, could drown a CT70 gasketed or not.
     
  6. Dennis McDonaugh

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    Why are the two coils different sizes?
     
  7. racerx

    racerx Administrator
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    Different functions
     
  8. hrc200x

    hrc200x Active Member

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    Did the sl70 for sure have a gasket there? Not showing on partzilla.
     
  9. Dennis McDonaugh

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    So the big one runs the ignition and the small one is for the lights and horn?
     
  10. racerx

    racerx Administrator
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    The lighting coil is physically larger and can be identified by the two leads + ground. The ignition coil has only a single lead + ground.
     
  11. Dennis McDonaugh

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    Thanks, I haven't taken it apart to see were the leads go.
     
  12. racerx

    racerx Administrator
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    This explains it better than I can...and with less verbal tonnage;)

    Screenshot_2020-04-13 dratv_2270_47130449 (JPEG Image, 1163 × 763 pixels) - Scaled (96%)(1).png
     
    Dennis McDonaugh likes this.
  13. Dennis McDonaugh

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    That's the one I'm looking to buy. They are currently out, but said they expect a new shipment within two weeks.
     
  14. Dennis McDonaugh

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    Can you remove the stator plate without draining the oil from the bike?
     
  15. racerx

    racerx Administrator
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    Lean it over on the clutch side, way over.
     
  16. Dennis McDonaugh

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    That's what I'll do when I get the parts!

    One more questions, I saw a you tube video of someone removing the and replacing the stator and there were two o-rings behind those two screws. I don't see them on the Honda parts breakdown nor does it look like the rebuild kit comes with them. Is there a source for them?
     
  17. racerx

    racerx Administrator
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    Oh yeah, you need those. Without them, you'll get a lot of leakage.

    Replace all 3 O-rings and do remember to lightly oil the large one, prior to installing the stator plate.
     
  18. dirtbkr188

    dirtbkr188 Active Member

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    Click HERE and look to the right side, part #15
     
  19. allenp42

    allenp42 Well-Known Member

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    If you're in a hurry, I have one used set of OEM parts that work fine. The points and condenser are OEM Honda and don't look that old or used either. I know everything works because I have tested it. Not as good a deal as brand spanking new kit from TBParts but will get you on the road a little faster.

    You have a couple of options:

    You can send me your stator and I'll fix or replace what is needed and return it to you. Shipping each way is about $8.

    Or I can send you what I have, already soldered up, and you just bolt it in place. $30 delivered.

    Again, the kit is a good deal so don't feel obligated. Just PM me if interested. Will gladly share pics beforehand.
     
  20. Dennis McDonaugh

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    Thanks, I just looked past them!
     
  21. Dennis McDonaugh

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    Thanks for the offer, but I think I'm going to wait for the kit. I may take you up on it later if they don't get the kits in when they said.
     

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