Vintage Dirt Bike Q & A

Does anybody know what the voltage from the mag from a 76 250MR should be? Also if i need to rebuild it does the MR take the same as 76 CR250. Im not getting a spark from the plug but don't really know what a good starting voltage is. Can anybody help?

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Ride it as if it were brand new

Robert- I had a similar problem with my MR however I knew it was my primary coil that was the cause. The primary coil is the one under the flywheel, the secondary coil is the one that has the sparkplug wire out of it. No other primary coil can be used as they are diffrent, Cr and MT etc. The official Honda shop manual says to check continuity between attaching stay (ground?) and the black & white wire on the plug out of the mag. Do you know for sure that it's the coil and not the points or secondary coil? Mine was damaged by someone using a screwdriver to hold the flywheel from turning while removing the nut. You might have to take the mag apart to test the coil, but see 1st if you have continuity. If the coil is in fact bad, I had mine rewound for $45.00 and back to me in 10 days, and I can get you the address if you need it. Gary

with all do respect, all i wanted to know is what should the voltage be from the magneto wire coming directly from the magneto. What is a good voltage reading from those wires, when cranked

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Ride it as if it were brand new

Faraday's priciple: It depends on how fast you spin it. Honda coils are typically 6VAC.

But you will never see that out of the coil with a VOM or DVM. They respond too slow and the other coils/magnets will affect the readings. You perhaps could check it with an oscilliscope or maybe a zener/led to check level.

IMO the way to do it is check coil resistance. Should be about 2 Ohms *with the points OPEN* if my DVM and MR coils are right.

Honda's own manual tells you to check for continuity, does not give voltage figures

Does this thing have a Kill button.
My CR shorted kill button and the flame died.
disconnecting wire to kill button got the fire lit again

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'84 Honda CR500
'84 CR125
'85 KX125
'83 IT490
'82 Maico 490
'80 YZ465
'75 Husky CR360 GP Mikkola
'75 CR250
'72 DT2MX
'91 XR200

Im just trying my best to get a while new electrical system piece by peice. The secondary transformer is in very poor shape. I want to replace this peice before it finaly breaks and im out of louck. Can i get this rebuilt or buy a new one with same ratio? Does anybody have any ideas?

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Ride it as if it were brand new