CDI box swap from '81 yz465 to '81 yz250?

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Oct 19, 2006
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#2
The rpm ranges of the engines are way different which would probably mean the advance curves would be way wrong and the rev limiter also incorrect.
 
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#4
It will most likely work. Back in '81 I raced a YZ125H and we used a yz80 black box on that bike.
 
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#5
cp380sx, think about how a 125 and 80 make there power. It is fairly simaler but a 465 makes a ton of power everywhere. 80 and 125 are alot more alike then a 250 and 465.
 
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#6
I still think it will work fine. Displacement doesn't really change the ignition curve requirements that much at all. If anything, the 465 has a little less advance at lower rpm. That would be a good thing with modern unleaded pump gas. It's not like anyone is racing their '81 YZ250 for money so squeezing every single pony out of it isn't that big of a deal.
 

fatboy570

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#7
I found the 81 YZ 465 cdi will interchange with the 81-2 IT 465, 80-81 YZ 465,and 82 YZ 490. Hope this helps