Author Topic: Arcing coils / Running issue / no top end  (Read 3722 times)

Online 73 sport

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Re: Arcing Dyna Coils Added pics
« Reply #30 on: December 24, 2025, 08:33:59 PM »
   I've had Dyna coils and distributer plate on my '74 Sport since the mid '70s. never a moments problem. I have silicon rubber plug caps, the insides are lightly coated with silicon grease. The coil caps are also coated inside with silicon grease. Many of the gripes I've seen on this site looks like rain, humidity intrusion. Not all ignition wires and caps can handle higher voltages produced by performance components. The complainers seem to have similar problems, they don't want to spend the money for quality components.

Offline baloo

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Re: Arcing Dyna Coils Added pics
« Reply #31 on: January 11, 2026, 12:40:49 PM »
Yes, Any update?
I'm having the same problem of backfiring at higher rpm - I have the Dyna system, which ran great until parked about 1yr ago. 
Thinking it might just be the coils (Dyna 5ohm) which test out OK per static tests with multimeter.
I'm thinking the coils just might peter out at high rpm (when I get backfiring - around 6000rpm)

Carbs cleaned out

Online 73 sport

  • Gosling
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Re: Arcing Dyna Coils Added pics
« Reply #32 on: January 11, 2026, 01:43:03 PM »
    Go to Google. Type in "What causes backfire at high RPM".

Offline Turin

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Re: Arcing Dyna Coils Added pics
« Reply #33 on: January 11, 2026, 09:37:36 PM »
It's not the Dyna ignition or the coils. Both have been swapped. Not the carbs either, those were swapped.

IOt has to be the NGK (racing) plug wires
2007 Griso 1100
1998 Centauro GT
1997 Daytona RS
1991 Rennsport California III
1991 LeMans 1000
1987 LeMans SE Dave's Cycle Racer
1985 Sidlow Guzzi
1984 LeMans III
1974 850-T Sport
1969 A-series Ambassador
1982 Alfa Romeo GTV6 Balocco SE 3.0

Offline michaell32

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Re: Arcing Dyna Coils Added pics
« Reply #34 on: January 11, 2026, 11:37:41 PM »
Weak valve springs cause this issue. The valves could be floating it the high rpm.
Edit: Nevermind. You already answered the other comment.
« Last Edit: January 11, 2026, 11:55:41 PM by michaell32 »
2003 California EV
2018 Suzuki DR650
78 Honda GL1000

Offline Turin

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Re: Arcing Dyna Coils Added pics
« Reply #35 on: January 19, 2026, 08:02:35 PM »
Some of my issue is the F@$K A$$ 2-1 pipe. Hail Mary pass, swapped a Rennsport 2-1-2 system from my stash and Voila... The bike revs to 8K with no jetting changes. Got more tuning to do, but this is a step in the right direction.





« Last Edit: January 19, 2026, 08:09:40 PM by Turin »
2007 Griso 1100
1998 Centauro GT
1997 Daytona RS
1991 Rennsport California III
1991 LeMans 1000
1987 LeMans SE Dave's Cycle Racer
1985 Sidlow Guzzi
1984 LeMans III
1974 850-T Sport
1969 A-series Ambassador
1982 Alfa Romeo GTV6 Balocco SE 3.0

Offline turboguzzi

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Re: Arcing coils / Running issue / no top end
« Reply #36 on: January 21, 2026, 03:50:08 PM »
Glad to hear you seemingly found the culprit.

Not sure an "exahust system issue" would have been top of my list, but one of the reasons i asked you for pics of the whole bike is that sometimes the problems is there staring at you.... :)

Now that i see it fully, wow, nice tool! some good goodies on it too...

Online Tkelly

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Re: Arcing coils / Running issue / no top end
« Reply #37 on: January 21, 2026, 05:03:33 PM »
Nice collection!

Offline Turin

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Re: Arcing coils / Running issue / no top end
« Reply #38 on: January 21, 2026, 05:40:58 PM »
That's not my Garage !!! Mine is loaded with old guzzi's.
2007 Griso 1100
1998 Centauro GT
1997 Daytona RS
1991 Rennsport California III
1991 LeMans 1000
1987 LeMans SE Dave's Cycle Racer
1985 Sidlow Guzzi
1984 LeMans III
1974 850-T Sport
1969 A-series Ambassador
1982 Alfa Romeo GTV6 Balocco SE 3.0

Offline Offcamber1

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Re: Arcing coils / Running issue / no top end
« Reply #39 on: January 21, 2026, 09:43:09 PM »
Rodent nest in the 2 into 1 pipe???


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