Help! pick up coils

Hi, I am a newbie to the site and just bought a non running 82 xj750j maxim. I am getting no spark at the plugs, coils ohm out ok but pick up coils I am not sure about. Or to red reads 2.8 ohms and blue to black read open. What should they read? Thanks

 

Welcome, don't forget to check your brakes/tires ar per the links in my signature Onto your issue, really you could do with the manual for the wiring diagrams etc, the colours you state don't tally with mine though. :?

My diagram for XJ750J has 3 wires for the pickups. Black which is common to both pickups & grey for one, orange for the other.

To measure the pickups you'd need to measure between black & grey and then between black & orange. Spec resistances are 650 Ohms

Not sure what you're measuring as there isn't a blue wire to the TCI nor a red to the pickups :?

 

There are a whole myriad of reasons you could be getting no spark, starting with a slightly weak battery. The electrical system is such that it is very possible (common, even) for a slightly weak battery to be able to spin the motor quite vigorously but then have nothing left to fire the ignition with.

Also, the stock fusebox is a known problem area. Plan on replacing or rebuilding it, the fuse clips crystallize and break all on their own. Start by checking the "IGN" fuse.

You're going to need a service manual; not just for this but for all of the other long list of things you'll be doing to the bike as well. And you do have a pile of work to do, whether you know it or not.

 

Just downloaded a Yamaha factory repair manual, xj650 with xj750rh addendum, should suffice for most issues. Bought a fuse box and assortment of type ATO fuses. Will replace it tomorrow, charge battery try again. Thanks for the advice.