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Discussion Starter · #1 ·
Hi All

I recently worked on my 81 250 superdream to get it back up and running. The bike was running rich with the occasional pop and bang, but nothing a good solid ride and some carb fettling wouldn't have sorted.

I bought the bike to turn into a cafe racer, so when I knew the bike was running ok I started work on changing it. Somewhere along the line (very likely it was the new lithium small battery I fitted that blew the main ignition fuse) the electrics have had a paddy and caused issues.

I've got a spark on left cylinder, zero spark on the other one, and once running the bike won't rev at all and will only idle with a fistful of throttle keeping it ticking over. The only other thing that I've changed has been new indicators front and back, plus a new LED tail light.

I've replaced lots of the usual suspects. New reg rect. New fuses. Replacement CDI. Replacement coil set which also included spark plug leads and caps. New standard battery.

I really have no idea what else to look at besides pulling the entire wiring loom, does anyone have any suggestions or previous experience with an issue like this?

Thanks in advance !

Daniel


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OK, it's possible to have spark on one side only IF there's a broken plug wire, bad plug end cap, bad plug or it was tested with both plugs removed. The coil fires both plugs at the same time, wasted spark ignition. You can test for spark by leaving one plug installed and connected and the other removed but the plug threads grounded to the head. You can swap the wires back and forth, doesn't matter which is where.
How is the compression? What plugs are you using? Do you have the FSM, factory service manual?
 

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Discussion Starter · #3 ·
OK, it's possible to have spark on one side only IF there's a broken plug wire, bad plug end cap, bad plug or it was tested with both plugs removed. The coil fires both plugs at the same time, wasted spark ignition. You can test for spark by leaving one plug installed and connected and the other removed but the plug threads grounded to the head. You can swap the wires back and forth, doesn't matter which is where.
How is the compression? What plugs are you using? Do you have the FSM, factory service manual?
I tested it before with both plugs out I think. Spent an hour or so on it the other day and it sparked on both sides but now wouldn't even run. Airbox open with only a thin filter in, plenty of fuel, battery connected, just wouldn't start at all....


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Verify that you have spark. Test with one plug installed and connected, the other plug connected and threads grounded to the head. If you have spark then all that's needed is fuel assuming you do have compression.
What work/repairs have you done previously?
 
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