Author Topic: 1980/1981 Yamaha YZ250G/H New Build CDI. Expressions of Interest.  (Read 3197 times)

0 Members and 1 Guest are viewing this topic.

Offline Devondan

  • Yama-God
  • ******
  • Posts: 2342
Re: 1980/1981 Yamaha YZ250G/H New Build CDI. Expressions of Interest.
« Reply #50 on: January 25, 2019, 04:27:12 AM »
Thanks Bill and Cookie!
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 DynoTronix

  • Yama-Legend
  • ***
  • Posts: 235
    • DynoTronix
Re: 1980/1981 Yamaha YZ250G/H New Build CDI. Expressions of Interest.
« Reply #51 on: February 10, 2019, 12:31:32 PM »
Update:

The second OEM CDI has been rebuilt, below are two photos.





I still haven't resolved the timing discrepancy between the two units.  One is about 5 degrees more advanced than the other.  Cooky sent me another OEM unit, but it appears to be lost in the shipping matrix somewhere.  I have been watching ebay for another viable candidate, but nothing so far.  I have to lock the timing down before I can build a prototype.  For now I am proceeding with the board layout.

I will not be able to fit all of the components into the same box size I use for most of the other CDIs, like the 23X.  The timing retard circuit requires 18 additional components, so the circuit board has to be bigger to accommodate.  I ordered some sample boxes, which should work well.  They are bigger than the 23X size, but still smaller than the 3R4 OEM unit.

Best regards,

Bill 

Offline DynoTronix

  • Yama-Legend
  • ***
  • Posts: 235
    • DynoTronix
Re: 1980/1981 Yamaha YZ250G/H New Build CDI. Expressions of Interest.
« Reply #52 on: February 12, 2019, 01:07:59 PM »
Update:

I received the CDI from Matt today and I wasted no time testing it.  I now have one CDI from Dan, and one from Matt, that seem very close in timing to each other.  Over the RPM range they are within 1 degree of each other, so that's good news.  I'm going to retest in another day or so, after Matt's CDI has completely warmed to room temperature.  The CDI was cold when I removed it from the packaging, so that could effect the timing.  Yes, temperature does make a difference, so I need to consider that in my analysis. 

Please ignore the timing specs I posted earlier in this thread.  I was using a 2X6 instead of a 3R4 rotor.  My thinking was that since the 3R4 stator uses the same coils as the 2X6, I should be able to use the same rotor too.  However, that was a bad assumption.   I bought a 3R4 rotor and discovered that the magnets are in a slightly different position from the 2X6, relative to the zero degree mark, so that difference produced incorrect numbers. 

So now the test engine is configured properly, even if the engineer is out to lunch.

Regards,

Bill


Offline Cooky375

  • Yama-Hero
  • ****
  • Posts: 310
Re: 1980/1981 Yamaha YZ250G/H New Build CDI. Expressions of Interest.
« Reply #53 on: February 12, 2019, 05:38:19 PM »
Good stuff Bill, good news that both are running the same giving you a confirmed place to start.

Cheers

Cooky

Offline Devondan

  • Yama-God
  • ******
  • Posts: 2342
Re: 1980/1981 Yamaha YZ250G/H New Build CDI. Expressions of Interest.
« Reply #54 on: February 16, 2019, 08:23:43 AM »
Great stuff Bill I?m looking forward to testing the final result! 😉😄
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)