Author Topic: 1980/1981 Yamaha YZ250G/H New Build CDI. Expressions of Interest.  (Read 8497 times)

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Offline Devondan

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Re: 1980/1981 Yamaha YZ250G/H New Build CDI. Expressions of Interest.
« Reply #100 on: May 17, 2019, 05:24:43 PM »
Yes Bill I was suprised too, although I am using a 8.99 eBay multimeter! The coil was clearly NOS and looked like it was made yesterday, no external sign of corrosion.
IT  400D - Trail riding
74 Montesa Cappra - Racing
YZ250 H - Racing
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Norton 250 Jubilee - Road
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Offline DynoTronix

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Re: 1980/1981 Yamaha YZ250G/H New Build CDI. Expressions of Interest.
« Reply #101 on: May 17, 2019, 11:45:44 PM »
Yes Bill I was suprised too, although I am using a 8.99 eBay multimeter! The coil was clearly NOS and looked like it was made yesterday, no external sign of corrosion.

Dan,

If you have another low-speed coil that measures the proper 1437 ohms, using the same multimeter, then I don't suspect it's the meter. 

By all means, install the coils that measure the correct resistance and see if there is a difference.

I feel like we're missing something.  I just can believe it even started with such a low resistance reading.

Bill

Offline Devondan

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Re: 1980/1981 Yamaha YZ250G/H New Build CDI. Expressions of Interest.
« Reply #102 on: May 19, 2019, 05:38:25 PM »
Me too Bill, but it is what it is. Interestingly I hooked up the other coils and zilch, nada, nothing .....no spark. In a way that doesn?t surprise me as it was either those coils or the CDI failing that led me to HPI in the first place.

I refitted the NOS coils (the one with the low resistance) and spark is resumed!  So the mistery continues

Back to the original set and the multimeter, the coil reads 1500 when set at 20k but when switched to 2k it reads 1000. Which is odd, everything else I measure with the meter is the same at what ever scale I use. I might treat myself to another one and see what that shows.

Anyway, a bit more testing this morning and a leakdown test, and if I can I?ll rig up a timing disc and strobe,  then I?ll get it to Pete for him to do the same (test that is!)
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

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Re: 1980/1981 Yamaha YZ250G/H New Build CDI. Expressions of Interest.
« Reply #103 on: May 20, 2019, 04:01:11 AM »
Dan, since the measurements are vastly different on the two scales, it looks like the meter is defective. 

Offline fred99999au

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Re: 1980/1981 Yamaha YZ250G/H New Build CDI. Expressions of Interest.
« Reply #104 on: May 20, 2019, 09:35:46 PM »
Unless it is not a multimeter, but a megger and you're breaking down the insulation.

Offline DynoTronix

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Re: 1980/1981 Yamaha YZ250G/H New Build CDI. Expressions of Interest.
« Reply #105 on: May 20, 2019, 10:28:33 PM »
Unless it is not a multimeter, but a megger and you're breaking down the insulation.
That would do it.   



Offline fred99999au

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Re: 1980/1981 Yamaha YZ250G/H New Build CDI. Expressions of Interest.
« Reply #108 on: May 21, 2019, 07:59:27 AM »
Looks like a Fruke. :)

Offline T.RexRacing

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Re: 1980/1981 Yamaha YZ250G/H New Build CDI. Expressions of Interest.
« Reply #109 on: May 21, 2019, 09:52:08 AM »
:D :D :D
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