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Honda CB250 RS stator coil help

Discussion in 'Honda 250cc Singles' started by siwilson, Nov 10, 2014.

  1. siwilson

    siwilson Active Member

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    Hi,

    Just joined this interesting looking forum and I'm hoping to get some help with a newly acquired Honda CB250RS (kickstart model). (https://www.flickr.com/photos/siwilson/15124995790/)

    I bought it as a non runner - it has no sparks. The previous owner said the stator had gone and had replaced it with a new electrex one (this one to be precise http://www.electrexworld.co.uk/acatalog/G47.html). Still no spark with this despite trying different CDIs and coils etc.

    I am fairly sure this stator is not right for the kickstart model, the voltage from the coil is very low when kicking, about 5v AC.

    I've managed to find another stator, but I seem to be missing something when I try to mount it.This is the back of the stator: https://www.flickr.com/photos/siwilson/15561641939/

    and this is the mounting "spider": https://www.flickr.com/photos/siwilson/15723861406/

    When I put them together, there's a gap, like this: https://www.flickr.com/photos/siwilson/15127585224/

    Can anyone help with which part is wrong? I'm beginning to think perhaps the replacement stator I've got is also from the later electric start model...

    TIA

    /Simon
     
  2. kiffsta

    kiffsta Senior Member

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  3. Murdo

    Murdo The Good Doctor Staff Member Contributing Member Ride and Events Crew

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  4. siwilson

    siwilson Active Member

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    Thanks :thumb_ups:
     
  5. TechHeadFred

    TechHeadFred Well-Known Member

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    Not taken mine out but it looks like this when attached to the cover:

    [​IMG]

    Honda original part number is 31120-471-701.
    Here's the part image from CMS:

    [​IMG]

    Think you might be right about the G47 stator being for the electric start model - it says so on the page you linked!

    After a bit of research it looks like there's a G201 that might be the model you're looking for, but it's out of stock at Electrex. http://www.electrexworld.co.uk/acatalog/G201.html


    Looks like you might also be missing the cable clamp?

    Cable Clamp.png
     
  6. RosscoM

    RosscoM Active Member Premium Member

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    is the pick up coil for the spark part of the stator... way to go honda... :(
    do you have all the original parts, if so, put it all back together with the original parts and DIAGNOSE where the fault is, you only need a multi-meter and the ability to follow the procedure in the workshop manual...
    don't forget the basic checks, the CDI unit powers up off the battery, make sure the battery is fully charged...
    the pickup coil is just a signal to the CDI unit, the coil will have a resistance... it will also generate a small voltage every time the magnet on the flywheel passes it,
    If there's a broken wire between the pick up and the CDI, no spark....
    make sure the coil/s has battery voltage on the + side, make sure the CDI unit is getting battery voltage, you have no idea how many times it's something simple like a blown fuse, and not a $300+ stator....
     
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  7. TechHeadFred

    TechHeadFred Well-Known Member

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    Ignition spark voltage coming through the stator coil seems to be a pretty common setup in Japanese motorcycles - I'm pretty sure my 2004 KLR650 has a similar arrangement, only with a starter motor.

    The other thing I'd suggest checking is the regulator/rectifier if your voltage is low. I'm trying to track down a cheap NOS or aftermarket one after buying one that didn't fit from a dodgy seller.
     
  8. RosscoM

    RosscoM Active Member Premium Member

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    Yamaha use a separate pick up... the stator output has nothing to do with spark production, only the pick up built into the stator in Honda's case, hence two connectors... one for charging, one for spark... the only way the voltage produced by the stator could affect spark, would be if the battery is run down and the stator isn't producing enough voltage to power up the CDI...
     
  9. TechHeadFred

    TechHeadFred Well-Known Member

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    Hmmm, I will have to check my other Honda and Kawasaki manuals and see how those ones are done.
     
  10. RosscoM

    RosscoM Active Member Premium Member

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    either way @TechHeadFred only one small part of that stator is critical to spark... the majority of it is generating voltage to charge the battery...
     
  11. RosscoM

    RosscoM Active Member Premium Member

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    @siwilson from your pictures, the spider has a groove on the inside, does that line up with a dowel or machined woodruff on the stator, the gap is confusing, sure you have the stator the right orientation, not in backwards... or out by 120 degrees... if it's all assembled correctly, the stator is wrong...
     
  12. siwilson

    siwilson Active Member

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    Unfortunately I don't have the original parts. The previous owner told me that the stator was physically broken and that he binned it. I have done quite a lot of diagnosis with a 'scope and multimeter and concluded that the output voltage from the pick up coil is insufficient to get the CDI to fire. (The CDI is an AC type and is not powered by the battery) Everything else (trigger pulse, coil, HT lead, plug etc. check out as far as I can tell). The trigger coil is separate.
     
  13. siwilson

    siwilson Active Member

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    Thanks. I am pretty sure that I now have two incorrect stators. Finding a replacement one is proving quite difficult, will keep looking.
     
  14. TechHeadFred

    TechHeadFred Well-Known Member

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    Let me know if you find anything. I might have a spare - will let you know once I rebuild the top end on one of mine.
     
  15. siwilson

    siwilson Active Member

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    No luck so far - definitely interested if you have a spare. Several places list the G201 one from Electrex but then don't have any stock. Electrex last made one in 2009 and are not going to make any more.
     
  16. siwilson

    siwilson Active Member

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    Just to close this thread out. I tried many places to get the Electrex coil - they all said they had it in stock but then turned out they didn't. I finally managed to source the right coil on ebay and now the bike's running. Sounds a bit rattly to me, but, all the videos of the bike I can find on Youtube sound the same, so maybe they all do that.

    /Simon
     
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  17. TechHeadFred

    TechHeadFred Well-Known Member

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    Might have to look for one of those myself, not sure any of mine work properly...
     
  18. siwilson

    siwilson Active Member

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    Th
    They're quite easy to check with a meter if you have one available.
     
  19. TechHeadFred

    TechHeadFred Well-Known Member

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    Oh I know. The problem is none of the multimeters I own have a low enough range to test the low resistance accurately.
     

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