Boyer black box problems.

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Nov 4, 2007
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Yesterday I had fit a boyer to my friend 's Commando, and no sparks ....
(all the wiring was newly redone with all grounds back to the battery , new coils it was at least the 20 th I had fitted without probs), so no hesitation, I go to the trouble shooting guide , follow the steps and found the black box with no sparks when touching the two wires comming from the stator (after unplugging them and touching the black box side ones ), so I jump to my shed , put a new one , OK it works , do the timing , synch the carbies and so and so , the day after same trouble, checking all the parts , no sparks , borrow the twin boyer coil on my Cdo , box out of service. Could it be two faulty box , or should I look for another track.........any help will be sincerly wellcome , that could be expensive at the end , though I will send them to Boyer for checking and may be warranty.
Was the battery fully charged, and giving a good voltage reading?

Did you check the voltage at the Boyer (White wire connection)?

Did you test it by connecting a wire from battery -ve (assuming it is standard Positive Earth/Ground?) directly to the Boyer box white wire?
Hi there, yes the battery showes 12,4 V, and the voltage between white and red at the black box was the same.In fact , I follow exactly the trouble shooting till the test of the trigger : touching both wire et the black box side from stator assuming to get any sparks, but no sparks and that was the second new boyer in two days , starnge , because i never had problem with the previous Boyer (at least twenty) I had installed .....
I just fitted a new boyer to a B44, it worked but because they have added a cutoff so it doesn't fire until it gets 200rpm the first touch of the wires produced no spark but the 2nd and subsequent touches did if done fast enough.
My Boyer was hopelessly dead. Pull your hair out dead.
I moved the ground wire coming out of the boyer box from the frame grounding and plugged it into a red wire in the generous wad of under-tank harness and instantly solved everything!
The original frame mount was checking out with a volt meter and had been used for years with no problem.

Best wishes.
Should we put a ground wire to the engine and thus consequently put the body of the coils at ground ???
The last coil in the wiring sequence (+) positive terminal should be grounded.

The engine should also be grounded at the head. Remember, the engine is not grounded through it's mountings, they are all isolated with rubber!
marinatlas said:
Should we put a ground wire to the engine and thus consequently put the body of the coils at ground?

If, by "body of the coils" you mean the coil cases? Then no, they do not need to be grounded, in fact if you can detect current between the coil cases and ground then the coils are faulty?
Hi , I have been , on the bike , the red wire go to the head, I had test with my own dual boyer plug ( to cancel any bad coils posibility),check the resistor plug cap (10 ohms ), NGK ones, they are OK too, new plugs, still no sparks!!!!!!!!
marinatlas said:
check the resistor plug cap (10 ohms ), NGK ones, they are OK too

NGK Resistor plug caps are normally 5,000 Ohms (5kOhms)?

Use x1k (x1000) Ohms scale if you have one, the reading should be: 5.0

Did you try wiring the red (+) and white (-) box wires directly to the battery?

There is one type of NGK resistor cap that is 10 kOhms which is the LB10EHF. All others seem to be 5kOhms: ... g_caps.htm

5kOhms caps are normally recommended by Boyer with copper spark leads/wires, but the MkIII analogue Boyer does not require RFI resistor caps or R plugs to be fitted. The Boyer Micro Digital and Micro Power ignitions must be used with 5 kOhm resistors.
Yes they are LB 10 (10 K.;Ohms), that's only what they had at my local japy dealer, plus I should admit cars plug wire (new but resistive at 2 K .Ohm), but when I test an hour ago it was with my own coil (boyer non resistive wire, fitted on their dual plug single coil). As soon as I can get spare black box , I will try with alternator unplugged and thus the podtronic , will have no influence too (all the charging system will be out).
But I had before to send the three black box to Boyer (one is one month old , two are a week old...)However thank you everybody for your collaboration , and patience .
Got Boyer on phone...the three boxees were shot; in order to find out the root causes they dismantled the boxes (or tested), and found that at least two were destroyed due to excessive HT current , this could be caused either by an erratic /bad ground of the engine (or return to the red wire), or excessive impedance/resistance of the HT leads/caps ( I run 10K ohms caps and 5 K ohms wires), so they will replace for free one box and the two other are for me (and I was fitting this Boyer to a friend's Cdo , for free/fun, so no more fun and for my pocket two boxes, cause I can't ask money to this guy , that won't be fair.......!).Hope it will work, after checking the return current from engine to battery with a bulb (it has been said it's better , cause it will put some load on it , and better than with a multimeter) , and then put copper wire with zero ohms resistance, as the plug's caps.
It's OK the Cdo runs , we have checked all the wiring (especially the return of ground from the engine, which was the suspect culprit) before to make sure , change the caps and wires .....but the engines stalled after few blips , check the new rubbish pet cock (half obstructed by the inside rubber) , change them , but one cylinder stay cool , should be the air jet obstructed more time today, have to come back home, but my friends feels better (two years and half since the first beginning of buying spares, and his first british bike).
I am jumping in to this because i see mtop have the ssame problem How do i know if the boyer module is good? the regulator? etc , If the Boyer is no good, should i replace itwith the same or is there something better. anks in advance
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