Going Electronic MK ll

[morris]

Having a wasted spark means it fires the same cylinder from the same Boyer coil on the stator so having swapped the leads should have eliminated caps, leads and coils. (Same as turning the stator plate 180 degrees?)

Well, not exactly, because if there's a fault in one of the stator plate coils, by turning it 180° it should show up on the other cylinder.
Your Boyer's rotor is turning at 1/2 the crank speed, but triggering a spark every 180°, which corresponds with every 360° crank revolution. My theory is that you have a good spark on both cylinders when the right cylinder is on compression and fires, and 360° later when the left one should fire you have a bad spark

[chaterlea25]

Gerry
A duff valve spring will return the valve ok at cranking speed so compression will appear normal
At running speeds the valve will not return fast enough and so misfiring occurs

Some time ago there was an other posting on a similar vein, it turned out that the valve(s) were sticking when hot  due to tight fit in the guides
A dose of upper cylinder lubricant in the petrol solved the issue

HTH
John

[Triton Thrasher]

Having a wasted spark means it fires the same cylinder from the same Boyer coil on the stator so having swapped the leads should have eliminated caps, leads and coils. (Same as turning the stator plate 180 degrees?)

Well, not exactly, because if there's a fault in one of the stator plate coils, by turning it 180° it should show up on the other cylinder.
Your Boyer's rotor is turning at 1/2 the crank speed, but triggering a spark every 180°, which corresponds with every 360° crank revolution. My theory is that you have a good spark on both cylinders when the right cylinder is on compression and fires, and 360° later when the left one should fire you have a bad spark

Doesn't the Boyer get its signal from both stator coils, for every spark?

[Gerry]

OK fellas, The first thing I am going to do is check the printed circuit board or stator plate which might just be out of center due to my having machined the housing   too big allowing the board to maybe off center enough to allow one coil to be slightly retarded or too far away from the magnet on the rotor. I might have to machine the housing out a little more and shrink a sleeve into it. Been much too hot for this ol' fella to get out the shed these last couple of days. Cheers. Gerry

[bsa-bill]

allowing the board to maybe off center enough to allow one coil to be slightly retarded or too far away from the magnet on the rotor.

As I understand these units I don't think the first bit (one side retarded ) can happen, the magnet passing the coil induces a current that acts as a trigger it either does or does not allow current to the ignition coil, a yes or no situation no maybe in between.
Now the second bit makes sense (too far away) so no current generated or not enough to get a yes, however I'm thinking it would have to be quite a difference in distance for this to happen, any possibility you could measure the gap between both sides.
The wasted spark in this situation adds a degree of difficulty in diagnosis, I'd suggest both plugs out and clamped together and to engine, then turn the engine via the back wheel with the circuit board visible, watch for sparks on both plus simultaneously when the stator passes each of the coils if one is too far away you will get no spark when the magnet passes it.
Hope that makes sense the way it's written

[trevinoz]

Gerry,
                    To save me from reading through the whole saga, when you swapped leads, did the problem swap sides? I would think that if the problem is with one of the pick up coils in the unit, swapping leads would swap the problem.

Trev.

[Butch (cb)]

I do know that on the V50 II which had (somewhat derided) electronic ignition the gap between the trigger and sensor for each side had to be spot on to each other. Although regardless of this the static and advanced timing could be OK, the gap effected at what point the electronics went up the advance curve. So with different gaps whilst on that curve you would have the two cylinders at different stages of advance. This manifested itself as a big flat spot coming up to 3k rpm.

[bsa-bill]

So with different gaps whilst on that curve you would have the two cylinders at different stages of advance

interesting stuff, that would suggest the unit can indeed measure the flux generated.

[Gerry]

Hi Guys, OK so here's the latest......tapered off a carb' flange spacer.....no change.....machined up a spacer for the electronic mag' to remove the slop so the stator plate is a nice fit.....no change....removed the carb' and reset the float height....no change....removed the rocker inspection covers and checked the valve springs and the tappet clearances....no change!! So now its head off and check the valve seating...again and maybe reseat the valves on the left hand cylinder. I have had enough for today so am going to celebrate my failures with a cup of tea an get my feet up. Start again tomorrow. ITS GOT TO BE THE BLOODY COMPRESSION. Cheers all and many, many thanks for all the help. It really is appreciated. Gerry

[Gerry]

OK Guys, stripped off the head to check valves are seating properly and found I have wasted my time....again. Poured a drop of petrol into the inlet and no leakage after 5 minutes!! Same with the exhausts. Checked the springs and all good. Head gasket is good also. Shoved my hand over the cylinder bores and both sucked my hand hard (no comments!!) Tomorrow  a good friend is coming round with a recon' magneto and another carb off his rocket Gold Star which runs great. So here we go again, put it all back together and firstly try his carb'. If that doesn't improve things I will replace the Boyer with his mag and try that. Will keep the 12 volt system though as I get a bloody good charge with the headlight on. WATCH THIS SPACE......I'm going for a lie down now to recover my poor old aching body.

[muskrat]

Don't let it beat you.

[chaterlea25]

Hi Gerry,
I just had a thought, Does the bike have dual exhausts or siamise?
It might be worth trying the bike with the silencers removed in case theres a blockage in one ????

HTH
John

[Gerry]

Thanks Muskrat, I shall forge ahead. Funny you should suggest that Chaterlea, once the exhausts and mufflers were off I stuck a piece of 3/4" pipe up the left hand one and its perfectly clear up to the first slight bend in the exhaust. I've got a feeling in me water that its the bloody carb'. Don't ask me why its just that nothing else makes sense!. Today I shall do the re assembly thing after making up a new set of gaskets and hope my mate gets here in time to align the pushrods into the rockers. Last time he came round I had been dicking about for hours trying to get 'em all lined up, he came round and Bob's your uncle!!! done in 5 mins'. with a small thin screwdriver!!! Don't you just hate that? As for starting it without the mufflers, its loud enough on the right side with 'em on, my neighbors will kill me. Takes me back to my innocent youth when I used to ride my Manx up and down my street bringing the neighbors out in droves "cheering me on"  Cheers Gerry

[Gerry]

OK head back on, rocker box on with help from my mate fiddling with the bloody pushrods!! Primary cover off and made and fitted a timing disk to the crank behind the spring and a pointer attached to the two 5/16" bolts that secure the inner case to the crank case. Thanks for the pics' of your set up Muskrat. Got out my dusty strobe light, started it up and checked the timing....got no flashing light at all so transferred the strobe lead to the right hand or offside plug lead and lo and behold all working. Revved the engine and timing is spot on at 33 degrees!!! So swapped the strobe back to the left hand or near side lead and still no light even though I do have a spark on that plug. Maybe, just maybe, I am homing in on the problem as it is still not combusting well on the left side. I also realised that I should be using suppressed plug caps which I am not!! Apparently electrical interference from the spark being un suppressed can cause a disruption in the Boyer magic box and also can cause it to fail. So next step is new leads, suppressed caps and a Boyer twin lead 12 volt coil which will be easier to fit than two 6 volt coils.  I haven't given up yet. Oh yes, forgot, I ran it without the mufflers and the right side showed a few flames but not the left side. Watch this space. Gerry

[muskrat]

Nice work Gerry.
Check the charge in your battery. The only time I've had flames out the pipe was when the battery was getting low and the boyer wasn't retarding. Charged the battery and was good as gold.
Cheers

I forgot to mention, don't use the bike battery for the timing light. Use another battery eg car/other bike.