My paso is a 1990 model 906 and when I bought it there was an interesting fault with the electrix , whilst riding , any increase in load on the electrical system ( turning on the lights , blinkers , brake lights or even the horn sometimes ) would result in a momentary loss of power accompanied by a back fire from each pipe ( large stainless drop a golf ball right thru ones ) and , especially at night , a 3 foot jet of brilliant blue flame ( they lit up building as I rode past). This phenomena occasionally manifested itself while starting . While this eventually became a pain in the arse I did have a lot of fun , jets of flame and LOUD bangs in time with the blinkers whilst riding round a roundabout or passing a cage and then flicking to hi beam saw them dissapear in the mirrors ( lift elbows ) to say nothing of starting the beast out side the bank. Any how I eventually traced the problem to a substancial voltage drop between the + battery terminal and the power feed to the magic box ( webber marelli ) under the seat. I replaced the multi pin plug assy's that connect the ignition switch and the right handle bar switch block to the wiring harness . These plugs are crap ( we call them molux plugs here in NZ ) and have had no problems since . I have also fitted relays to the headlights and ditched the air box in favour of a K&N filter assy. At 60,000ks paranoya (and a little curiosity ) saw me strip the donk in search of the rumbly berring I was sure lurking in there somewhere (turned out to be road noise comming up thru the fairing ) but the only thing I could find to "fix " where the oil seals in the clutch and cylinder head /camshaft YAHOO !
HOT TIP when "doing " the valves, plug the oil return holes under the rockers with grease as there is something bemuda triangle ish , black holey about these that will cause any dropped / fumbled valve collets to go straight down these holes.......after reassembling and refitting the motor.....this didn't happen to me .....no way.......shit !

Hi there Mc Tool
you are experiencing what i call the "keybanger phenomenon". you can induce this while riding at speed, keep the throttle open, flick off the kill switch (or the key) for about a second, then switch it back on. it works great in tunnels, and is funny as hell if you do it in a hi-rise parking lot while riding down the out ramps between floors as it sets off car alarms all over the place. all that it is doing is momentarily stopping the spark and pumping raw fuel through the system, then re-igniting it, resulting in external combustion (hence the noise and flame). on one occasion i have actually blown the end cap off my exhaust doing this, but thats another story.
getting back to your problem, it seems you have an electrical leak, which grounds your coils (effectivly killing the engine) when said switches are engaged. My knowledge of the elctrical system is very basic, so while i am able to (try to) diagnose the problem, unfortunately i am unable to suggest a cure, except take it to an auto electrician.
duckboy

When I had the 906, mine also used to make those big bangs.
People used to be terrified, and in my garage some rubbies used to drop from the ceiling .
No matter, those "big bangs" used to happen only at the start or when I was killing engine by the switch.
I never troubled about it.
I always thought about an eccentricity of the bike.
Ciao

Start with the easy things, Unbolt and clean every GROUND (earth) connection that you can find. Clean, Clean , Clean. Use scotch brite or sand paper to make them sparkle. After this test ride the bike to see if your problems go away.

This sounds like the Ducati wiring loom syndrome. Because the ignition is the last appliance on the loom the voltage to it drops if eg. the headlights are used, cutting the spark. Use a relay from the starter solenoid + connection to the ignition to give it a higher voltage. Goes away totally.

Does the 906 suffer from the same problems as the 750?

viewtopic.php?f=1&t=173

...quite same! All 906 have that Marelli digiplex and SOME 750 modells also. most of 750 Pasos have Kokusan system, what is very good..... That is biggest diffrence between 906 and 750 electrics..... Remembering, that 906 have bigger generator....

I had the problem when my battery terminal worked loose. It took out my clock at the same time.