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Discussion Starter #1
So I have a 1971 Triumph Bonneville running Boyer ignition. The right side isn't firing. I checked the coil it's in spec. I put in a sparkplug and crank over and there is spark. When the sparkplug is in its not firing. The pipe is cold. I pull the cap off. No difference. Any thoughts would be appreciated.
 

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When checking spark with a Boyer be sure the plugs are grounded. I think you can damage the unit if not.
 

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keeping in mind what nanonevol said above, when running on one pot if you pull the RHS cap say 1/8 - 1/16 of an inch from the top of the plug does it cut in?.
 

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The dreaded Boyer Branson ignition eh? Start by checking compression...if that's fine then move on. It might be as simple as a dead plug...have you tried simply swapping them around? Std plugs are too cool to run well with modern gasoline (I have had great luck running slightly hotter plugs). If that gives no results try switching the wires and plug boots. If that fails to indicate any issues it is probably the coil...try swapping them around. it that doesn't make any difference, then you have a fuel/ carb issue. If you've gone through everything and still got no life on one cylinder, it's the 'black box'...yes beleive it or not, I've had them fail exactly this way right out of the box...this is one of the reasons I am not a fan of electronic ignition sytems.
 

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I too struggled with a messed up Boyer black box on my Triumph. Made sparks fine but couldn't get the bike to start and run. Sent it out for diagnosis (John Healy) and found out it was lunched. Wasn't advancing properly or some such shit. Finally ditched it for points.
Indulge me, I like to show it off:
 

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Discussion Starter #7
Update. Checked Compression (Fine), valve lash (Fine) took of Amal carbs and cleaned (fine). Changed plugs (fine) Switched plug wires from the Gill micro coil, left side fires right side still doesn't. Check the pickups (fine) I'm thinking the coil. Any suggestions on a replacement for a micro dual coil. I believe 4.5 ohms? Thank you in advance.
 

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What version Boyer? MKIII, IV, Micro Digital, Micro Power?

How Can I Tell What Ignition System Is Fitted On My Bike?
Look for the colour of the ignition unit and what type of coils you are running:

MKIII and MKIV - ignition boxes are black and run with the original coils or similar replacements

Micro Digital - ignition boxes are red (old style Micro Power ignitions were also red) and run with the original coils or similar replacements

Micro Power - ignition boxes are blue (old style Micro Power ignitions were red) and run with miniature specialist coils

ID units - positive units are red, negative units are black (these systems both have LED's positioned at the top of the unit)
 

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isn't this a 'if you think it's electrical it's probably a fuelling problem'?.
the ignition runs on wasted spark, the left pot fires every which way coil is directed , the motor starts .all be it on LHS only, so timing is ok, plugs changed and there is a spark. Cpmpression ok.
The only things left particular to RHS is carb' (bpnneville twin carb'). Checked carb's are synced' and no manifold leak?.
 

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Why not consider a twin output coil? Brit Cycle Supply usually has them in stock and can give you the correct one for your ignition system.
 

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Discussion Starter #15
Update. Thank you everyone for your help on this. I solved the issue. I contacted Boyer Bransden and they sent me a check list. I checked the electrical system and it was all in spec. I pulled the carbs and checked. All clean and in spec. I then checked the compression. The right side that appeared to be not firing had half the compression of the left side. I pulled of the head to discover severe carboning on the right side. I believe the carbon was causing the valves not to completely close. I have dropped off the head at a local shop to go through. I'll update once I get it back together.
 

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From the look of the head, you should check the rings.
 

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Agreed...if you've gone this far, you might as well pull the clyinders too and check those rings.
 
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