Commander breakdown.

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mfremlin
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Commander breakdown.

Post by mfremlin » Sun Jun 03, 2018 7:29 pm

Hi guys.

I wonder if anyone can help with a breakdown I experienced today. Running along on a motorway at a good pace when the engine suddenly cuts out. Stop on the hard shoulder and have ignition, fuel and the temperature is good. Try a re-start and nothing. After three or four minutes try again and starts. Lovely tick over and off I go again. 10 minutes later (at a much reduced speed) same thing happens again. Three or four minutes later and re-starts no problem. Manage to get home ok and a quick look at connections etc reveals nothing obvious. The only thing I have noticed is one coil seems a lot hotter than the other. Would one coil failing cause both cylinders to stop working? Any suggestions would be very welcome as I hope to take this bike to Austria.

Thanks, Mark.

Anthony Duffield
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Re: Commander breakdown.

Post by Anthony Duffield » Sun Jun 03, 2018 7:58 pm

Mark,

In Italy at the NOC rally one of the other Commanders had a similar problem when the trigger was overheating, if the trigger is OK I would suspect the electronic ignition.

How long have you owned your bike, what make of electronic ignition do you have?

Tony

mfremlin
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Re: Commander breakdown.

Post by mfremlin » Mon Jun 04, 2018 4:35 pm

Hi Tony

Thanks for the prompt reply. Have had the Commander a few years now and never had a moment of trouble since the engine re-build which included a 5000 mile trip around Europe. It has the Norton digital system ignition with a 'half effect trigger' (whatever that it) fitted. My bike is a naked Commander so has plenty of airflow around the electrical components. Although the way the engine suddenly cut out and the re-started after three or four minutes does seem to point towards something over heating.

Cheers, Mark.
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Joe
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Re: Commander breakdown.

Post by Joe » Mon Jun 04, 2018 9:12 pm

Hello Mark,
This is almost definitely the ballast resistor breaking down probably through old age, heat or a combination of the two. The ballast resistor is installed on the coil mounting plate and it directly feeds both coil + terminals from the ignition 10amp fuse.
As a quick fix you can remove both brown and white wire Lucar connections from the ballast resistor and connect them together, this will give a full 12volts to the coils rather than the 6 volts they are supposed to have but it has never bothered my well used bike before I replaced both coils for 12volt type. I ran it for years with 6 volt coils.
Good luck.
Joe

johnbirchjar
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Re: Commander breakdown.

Post by johnbirchjar » Mon Jun 04, 2018 11:27 pm

Hi Joe,So let me see if I have this right.Replace the two 6v coils with two 12v,join the wires that are pluged into the Ballast Resister and "hey presto" no need for a ballast resistor Very Happy,so if it's that simple, why did Nortons fit 6v coils in the first place?J.B.

Joe
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Re: Commander breakdown.

Post by Joe » Thu Jun 07, 2018 2:28 pm

Hello Mark / JB,

I’ve cut and pasted Richard Negus’s excellent explanation of how it all works from his posting of July 10th 2013, I hope you don’t mind, Richard.
Does explain all.

In the original Boyer, the orange wire starts from the starter motor terminal of the solenoid and is only live when the solenoid is energised.
That orange wire goes to the Boyer box and comes out as the brown/white feed to the coils; it isn't connected to any of the gubbins inside the box.
The brown/white goes to coils +ve, bypassing the ballast resistor and giving the coils full battery voltage so long as the starter button is pressed. Of course, the starter motor is taking around 100 amps from the battery so its voltage is reduced below the normal 12.7 volts. As the coils are 6 volt type, there's still a good spark.
When the button is released, and we assume the engine is running, that bypass is ended and the ballast resistor drops battery voltage to the coils to around 9 volts which again produces a very good spark.
When the ballast resistor corrodes and goes open-circuit, that explains why the engine starts and runs only when the button is pressed.
As the Startright digital box was designed to be a direct replacement for the Boyer, it has the same wire connections.

Many thanks, Joe

johnbirchjar
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Re: Commander breakdown.

Post by johnbirchjar » Sat Jun 09, 2018 12:02 am

Hi Joe,would the Startright Box be the "MINIMAG" one (that I have on my bike)and I can bypass the Ballast Resister just by connecting the two wires?
I very nearly set fire to the old girl when one of the wires came off the Ballast Resister(dislodged it removing the battery) and it was "shorting out" on the frame, fortunately I noticed the volt meter showing a massive discharge,(it smoked a bit as well wink)and,(also fortunately) I was tinkering with the bike in workshop and not out riding,things could have turned out very nasty evil,J.B.

Joe
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Re: Commander breakdown.

Post by Joe » Sun Jun 24, 2018 9:00 pm

Hello JB,
Apologies for not replying earlier. Yes, the startright box was made by Julian Kemp at Minimag.
Regards, Joe.

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