Hi all 900ss with 750 paso ignition help

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startline
Posts: 6
Joined: Wed Jun 17, 2015 5:55 am
model: 900 SS
year: 1990
Location: UK

Hi all 900ss with 750 paso ignition help

Post by startline »

Right hoping for some confirmation on a digiplex 2 ignition fault, my 1990 bike has stopped sparking on the rear cylinder at 3700 rpm rev it up and rear cylinder cuts out, remove plug cap ground a new plug confirm s spark literally stops!, changed coils wiring from front to back and surprisingly it still stops sparking on the rear cylinder which indicates to me pickup or digiplex, pick up either works or not as far as I know and front is fineso assuming a new digitplex is required, front cylinder is fine on either coil and everything else passes as ok any thing I have missed? And I also assume a Paso 750 digiplex would work ok, air tube is also ok as is the digiplex earth HELP :-)
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Brutus
Posts: 257
Joined: Sun Jan 16, 2005 12:00 am
model: 750 Paso
year: 1989
Location: The Netherlands

Re: Hi all 900ss with 750 paso ignition help

Post by Brutus »

Hi, did you changed the coils also from vertical to horizontal..? Suppose you allready tried other spark plug cables etc to be sure..?
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higgy
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Re: Hi all 900ss with 750 paso ignition help

Post by higgy »

check the ignition switch
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Norman38
Posts: 5
Joined: Tue Jun 16, 2015 9:31 am
model: 750 Paso
year: 1988
Location: Germany

Re: Hi all 900ss with 750 paso ignition help

Post by Norman38 »

Has the pickup-line the greatest possible distance to the ignition cables?
startline
Posts: 6
Joined: Wed Jun 17, 2015 5:55 am
model: 900 SS
year: 1990
Location: UK

Re: Hi all 900ss with 750 paso ignition help

Post by startline »

Yes 're coils, rewired them both, same fault, the pickup is working fine to the horizontal cylinder and both cylinders are fine to3700 rpm when the rear stops sparking, ignition switch must be ok because it's starting fine
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Derek
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model: 907 I.E.
year: 1994
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Re: Hi all 900ss with 750 paso ignition help

Post by Derek »

But the ignition switch is well known weak point and can develop resistance across the contacts dropping the volts on load. If the volts are down that could be a reason for the sparks stopping on the rear cylinder. The rear may be more sensitive to a reduced voltage. The cure for the ignition switch is to fit a relay to do the switching, triggered by the ignition switch.
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higgy
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Re: Hi all 900ss with 750 paso ignition help

Post by higgy »

ignition switch must be ok because it's starting fine
maybe yes maybe no

The purpose of the relay mod is to eliminate the ignition switch as a well known trouble spot and to lower the electrical stress on the switch to prolong its life. Moving the headlight load away from the switch also helps with ignition issues as well as the life of the switch
Ducati,making mechanics out of riders since 1946
There's no problem so bad that a little fixing can't make it worse! : )
If it ain't broke keep fixin it till it is
88 750
90 906
92 907ie
startline
Posts: 6
Joined: Wed Jun 17, 2015 5:55 am
model: 900 SS
year: 1990
Location: UK

Re: Hi all 900ss with 750 paso ignition help

Post by startline »

Paso ecu fitted and now perfect :-)
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higgy
paso grand pooh-bah
Posts: 3327
Joined: Tue Jul 29, 2008 9:50 pm
model: 907 I.E.
year: 1992
Location: Hilltown,Pennsylvania
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Re: Hi all 900ss with 750 paso ignition help

Post by higgy »

just got lucky, was a wiring issue most likely
Ducati,making mechanics out of riders since 1946
There's no problem so bad that a little fixing can't make it worse! : )
If it ain't broke keep fixin it till it is
88 750
90 906
92 907ie
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