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Hi, I'm in SW Ohio and I'm here for help fixing my girlfriend's 1978 CB400T II HaWk.

The problem is that it only seems to spark when it wants to. It'll start up sometimes, and who knows how long it'll keep running. Lately, it's been about 3 seconds to not at all. Carbs are freshly rebuilt, balanced, and adjusted. I've used a spark plug checker to confirm it's not firing. Plugs are new (and gapped), and the coil and CDI seem to be ok per the resistances listed in the factory service manual. What doesn't seem to be ok is the resistance between the white and green wires on the generator harness (Infinite ohms per this link: https://www.rexs-speedshop.com/wp-c...250400N-CB250400T-generator-testing-guide.pdf all other resistances are within spec). I've removed the rotor and the epoxy potting on the pickup inside the stator is cracked, leading me to believe that's what needs replacement. I can't seem to find one for sale.

She's on my case almost constantly about getting this thing up and running so she can ride, in the meantime she keeps stealing my airhead BMW so I can't ride. Help!
 

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It uses a double ended ignition coil, if it's running the stator is ok. Is the spark plug on the dead side wet or dry?
 

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The CDI can cause this as its going bad and can only be tested by a special tool and you cant use an OHM meter to do it. You can get a stator rewound at Custom Rewind about $250.00 plus your core and shipping. 205-796-7282 Test your coil and if its ok then have the stator rewound . If still a problem you will have to replace the CDI.
Just my thoughts.

Bill H
 

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Ohm reading G-W should be 400 - 500.OHMs The white wire is part of the trigger that tells the CDI when to fire the plugs. Might be your problem. Just for info this is a 360 degree motor. Both pistons go up and down at the same time. It has a wasted spark system. Both plugs fire at the same time. When number one cyl fires on a compression stroke number two fires on an open exhaust valve. Then number two fires on an compression stroke and number one fires on an open exhaust valve. Sorry if you all ready knew this.

Bill H
 
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