Ducati m750 doesnt start. backfires. (video)

[zatonic]

I have an 01 m750 that I just replaces the pickup coils on. Well at first I had the pick up coils wires backwards so It wouldn't run properly. It would just stall. and run on only one cylinder. Well After a while I figured that part out and got it running just right. I jumped on it and went to the gas station to get some gas. On my way there i get some misfires and backfires. Starts to run on one cylinder then cut back to two. Didn't get in, Barely make it home. Next day I try to start it, and nothing. Except these sputters and flaming backfires from the exhaust.

Both plugs get spark, both cdi's, coil's and pickup's seem to read fine on the ohmmeter. Not seeing any pinched lines.
I did put 2 fresh gallons of gas in the tank that had about half a gallon left. Could the old gas cause this? It did sit for a couple months. Clogged fuel filter?

I tried putting a little gas straight down the carb hoping for a jump but nothing.

Battery gets 12.5 volts

This all started right when I got an aftermarket tail light off ebay with intergrated led blinkers. i had it plugged in wrong at first and blew a fuse, but replaced fuse. But that day I tried to run it is when it just stalled and wouldn't start back up, ended up being a bad pickup coil.

Any imput will be appreaceated, I'm almost ready to give up and take it to a shop


Ducati m750 not starting

[needtorque]

So to clarify it was running perfectly before you messed with the wiring?  Then you put on an aftermarket tail and since then it has been running poorly? Have you tried putting the stock tail assembly back on?

Backfiring through the carbs like that sounds like a timing issue to me but if it was running fine until you put on an aftermarket electrical item I would start with going back to stock and double checking your wiring.  

To be perfectly honest it almost sounds like it 180 degrees out of time.  At any point in your repair process did you mess with the timing belts?

[Howie]

Did you check ignition timing and gap when you replaced the coils?
With the horizontal cylinder at TDC the reference marks on the pick ups should match thr reference marks on the flywheel.  The gap should be .7+.1 mm.  You need a non magnetic feeler gauge for this.  If you did not remove the bracket timing did not change.  You might want to recheck the connections to the module.  White(1) and red(2) for horizontal,  black(3) and red(4) for the vertical.

[2 Wheel Wanderer]

I'm no mechanic but could it be possible that when you had the wires backwards that your plugs got soaked in gas and aren't dry enough spark correctly?

Just throwing it out there...

[Howie]

I'm no mechanic but could it be possible that when you had the wires backwards that your plugs got soaked in gas and aren't dry enough spark correctly?

Just throwing it out there...

Good throw!  Check that too.

[zatonic]

So I had my mechanic neighbor determain that it has a very weak spark. The bottom cylinder  plug only gets about half inch spark when you plug a Phillis head into the boot and come close to the frame. The spark has some orange in it which e said means it's weak. And the top cylinder is even weaker with a spark only about quorter inch from the metal frame and it us also orangeish and blue. We tried spraying brake cleaner down the carb to see if the spark would atleast clear that out since it's
More comustable than gas   Not even that would fire. So I think that tells me it's not the carb? Possibly bad coils? Or cdi's? Sorry if the format is funny I'm on my phone typing

[Howie]

run a resistance check on the ignition wires.   Connected to the coils going from the ignition wire to ground you are looking at 19.5 K ohms + 20%.  While you are at it you should check primary resistance, small terminal to small terminal.  Look for 4.5 ohms + 15%.  The terminal caps that attach to the plugs should read 5K ohms +10%  These numbers assume stock parts.

[koko64]

If your coils do turn out to be buggered, you will not regret buying Dyna coils. I could hear the stronger combustion with them at idle. My stock coils were servicable but not sharp. A good upgrade to old, stock parts.