Author Topic: 1980/1981 Yamaha YZ250G/H New Build CDI. Expressions of Interest.  (Read 21171 times)

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Offline Devondan

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Re: 1980/1981 Yamaha YZ250G/H New Build CDI. Expressions of Interest.
« Reply #70 on: April 11, 2019, 05:30:15 PM »
Great news, thanks Bill, if it makes before the 21st it will get its first test then!
Dan
IT  400D - Trail riding
74 Montesa Cappra - Racing
YZ250 H - Racing
Norton ES2 500 trials
Norton 250 Jubilee - Road
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Re: 1980/1981 Yamaha YZ250G/H New Build CDI. Expressions of Interest.
« Reply #71 on: April 14, 2019, 09:39:58 AM »
While the prototype is in transit to Devondan, I thought I would post a timing graph of the NOS CDI.  The new CDI is calibrated to match this profile.

Regards,

Bill


Offline Devondan

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Re: 1980/1981 Yamaha YZ250G/H New Build CDI. Expressions of Interest.
« Reply #72 on: April 28, 2019, 03:59:39 AM »
Thats interesting Bill, very different from the HPI CDI. 

Your CDI arrived today, after being held hostage by customs 😡 for a couple of days,  still it?s here now and good timing as I?m just changing the crank seals so have taken the old ignition off. With a bit of luck I should get it running in the week to test it and have a race meeting on Sunday to really put it through it?s paces.

I?ll keep you all posted, and thanks again to Bill!

Dan
IT  400D - Trail riding
74 Montesa Cappra - Racing
YZ250 H - Racing
Norton ES2 500 trials
Norton 250 Jubilee - Road
Norton 350 Navigator (in boxes)
Norton 350 Single M50 (in boxes)

Offline Devondan

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Re: 1980/1981 Yamaha YZ250G/H New Build CDI. Expressions of Interest.
« Reply #73 on: April 30, 2019, 06:43:32 AM »
Ok I?m getting my bike ready to fit Bills prototype CDI, I was checking my coils and looked up the resistance in the Yamaha service manual, it says low speed coil 1,437 ohms and high speed coil 500 Ohms, It also says pulser coil 500ohms.

The spares book gives the same part number for both low speed and high speed coil, no pulser coil is listed. So how do they have a different impedance if they are the same part?! Or am I being thick?!
Dan
IT  400D - Trail riding
74 Montesa Cappra - Racing
YZ250 H - Racing
Norton ES2 500 trials
Norton 250 Jubilee - Road
Norton 350 Navigator (in boxes)
Norton 350 Single M50 (in boxes)

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Re: 1980/1981 Yamaha YZ250G/H New Build CDI. Expressions of Interest.
« Reply #74 on: April 30, 2019, 07:54:10 AM »
Dan,

The expected values you have are correct.  The way the charge coils are connected they share the red wire.

Brown to Red: 1,470 ohms
White/R to Red: 500 ohms

Because of some steering diodes in the CDI, these coils have a dual purpose.  For example, when the high-speed coil is charging the capacitor (Red wire), the White/Red wire is essentially connected to ground (earth).  I say essentially because it is really one diode drop away from ground, or about 0.7 volts. 

Hope that helps.

Bill

Offline Devondan

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Re: 1980/1981 Yamaha YZ250G/H New Build CDI. Expressions of Interest.
« Reply #75 on: April 30, 2019, 04:10:21 PM »
Thanks Bill I have 1500 on one which is fine and 1900 which isn?t, I?ll order a new coil from eBay, but I?m slightly worried that the 250g had two different coils and the 250 had 2 the same assuming the parts book is correct?
IT  400D - Trail riding
74 Montesa Cappra - Racing
YZ250 H - Racing
Norton ES2 500 trials
Norton 250 Jubilee - Road
Norton 350 Navigator (in boxes)
Norton 350 Single M50 (in boxes)

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Re: 1980/1981 Yamaha YZ250G/H New Build CDI. Expressions of Interest.
« Reply #76 on: April 30, 2019, 09:18:15 PM »
I think the parts book has a mistake.  The YZ250H should use the same coils as the YZ250G, which are 3R4-85520-11-00, and 2X6-85567-10-00.  To further prove this point, you'll notice that the parts book calls for the same stator assembly on both the G and H models, 3R4-85510-11-00.  Since the assembly includes the coils it seems unlikely that there would be two different coil arrangements under the same part number. 

Bill

Offline Devondan

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Re: 1980/1981 Yamaha YZ250G/H New Build CDI. Expressions of Interest.
« Reply #77 on: May 01, 2019, 02:53:36 AM »
I think you are right Bill, it?s a mistake. I?ve just checked my coils again, high speed is 495, which is good, low speed is 1052 which is out of spec, I?ll buy a new os rather than rewind it.

Ok update I?ve been looking on line for a replacement coil, but none look like mine, so after a bit more research I?m pretty sure that my coils are from an 82 yz, they were working well until the CDI and one coil failed. Anyway I?ll buy two NOS 2X6 coils ( the correct ones) to make sure everything works as it should, I doubt I?ll get them by the weekend Bill, but you never know!

Photos to follow.

My stator, metal bits are 3R4



250J stator ..... see the similarities!



250 coils:





I may need a pic to help me wire them up when they arrive!
Dan
IT  400D - Trail riding
74 Montesa Cappra - Racing
YZ250 H - Racing
Norton ES2 500 trials
Norton 250 Jubilee - Road
Norton 350 Navigator (in boxes)
Norton 350 Single M50 (in boxes)

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Re: 1980/1981 Yamaha YZ250G/H New Build CDI. Expressions of Interest.
« Reply #78 on: May 02, 2019, 11:35:49 AM »
Dan,

It think the rotor and stator in your photo are the wrong ones for a YZ250G/H.  I believe the rotor should be M100-27.  I have found that the rotor magnets can be indexed slightly different from one part number to the next, so please check this.  I ran into this issue early on in the project.  I was using a 2X6 rotor, and I was getting timing numbers that didn't make sense.  I finally got the correct rotor, M100-27, 3R4-85550-10-00, and then the timing made sense.

As you said, the stator looks to be from an 82 YZ. 

The 2X6-85566-10-00 will work for charge coil 1, it was later superseded by 3R4-85520-11-00. 
Charge coil 2 should be 2X6-85567-10-00.

Bill

Offline Cooky375

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Re: 1980/1981 Yamaha YZ250G/H New Build CDI. Expressions of Interest.
« Reply #79 on: May 02, 2019, 02:16:32 PM »
I'll check mine tomorrow and take a photo.