The BSA A7-A10 Forum
Technical (Descriptive Topic Titles - Stay on Topic) => Lucas, Ignition, Charging, Electrical => Topic started by: Catz on 17.03. 2023 15:25
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As per instructions from Muskrat i've posted up over here,
i've put a 12v ignition by Boyer Bransden bought from SRM and just can't get the bike to fire up.
It nearly wants to, has a few backfires and that's it. New Yuasa 12 volt battery, getting a spark at the plugs, set it up as per SRM instructions. There's an on/off switch when at one stage today i turned it on and it backfired without kicking over. Everything is new apart from the dynamo, could it be that? No air filter, took it out as i thought it might be restricting air flow. Jets are standard for the 1960 A10 with Monobloc 389, also all clean. Petrol comes out when tickled.
I'm at my wits end with it though i know it can't be much needed to fire up. Any help is much appreciated.
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The obvious first question would be, did it run before you fitted the BB unit?
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Yes mate, ran good.
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I know nothing about electronic ignition but.... your symptoms sound like swapped HT/firing positions.
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I'll go and swap the leads round but it shouldn't make any difference if it's a wasted spark set up should it?
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I'll go and swap the leads round but it shouldn't make any difference if it's a wasted spark set up should it?
Well, that was why I prefaced my comment with "I know nothing about electronic ignition but."
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I tell you what mate, you're my hero, it's only gone and fired up. Glory be. Thanks a lot. *smile*
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You have no idea how pleased that makes me! 👍
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I tell you what mate, you're my hero, it's only gone and fired up. Glory be. Thanks a lot. *smile*
Sounds like one of the plug lead/caps wasn't making good contact then, as they both fire together on a wasted spark system as you said.
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Thanks for your reply, i'll check it out when i tidy it all up. Don't want to mess it up now.
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GB the resident sparky !!🤔😀
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G'day Catz.
Yes depending on where the "pick ups" are when you turn the unit on it will give a spark.
Do you have a coil with two leads coming out? It should. The Boyer sparks both plugs at the same time so one side is "wasted".
I'm going with Re on this one.
Now I've said it a dozen times. The only real way to time them is with a strobe and degree wheel. A bit of a job but once it's set you can forget it for 50,000 miles or until you rebuild the motor.
Cheers
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Now then Musky,
yes it has a coil with two leads coming from it.
I've left the degree wheel in place on the end of the crank and i've got an old strobe light in my cabinet and i'll give that a go ASAP.
I'll say it again, top forum with top people. *respect*
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Just a thought, I don't know anything about Boyer, but I fitted a Pazon to one of my bikes which I think could be similar, I removed the A/R unit and replaced it with a solid alloy gear as the electronic ignition takes care of the A/R bit itself
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Just a thought, I don't know anything about Boyer, but I fitted a Pazon to one of my bikes which I think could be similar, I removed the A/R unit and replaced it with a solid alloy gear as the electronic ignition takes care of the A/R bit itself
Yes, that's the same as the BB.
Now onto the use of the strobe which i think i know what i'm doing but just need a bit of clarification as the SRM instructions are not the best in my opinion.
Warm the engine up and set the tick over at 3000rpm, i've got no tacho so i'll just set it spinning fast, then point the strobe at the timing disc and pointer while adjusting the pick up plate until, according to SRM, the reading is at 33° BTDC for unleaded fuel.
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If "spinning fast" is much below the quoted 3K rpm, then the timing may end up being set a fraction advanced, as I'm assuming the programmed curve doesn't flatten out until that speed? Which is probably about 50mph in top gear equivalent.
(Have to say, I haven't enjoyed playing with these things much either!)
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G'day Catz.
I use a separate 12v battery so it doesn't take any power away from the ignition. Hook strobe up to that battery and the pick up lead (note the arrow) to the spark plug lead.
Just point the light at the disc and increase the revs till you see the flash stop moving, that is full advance (easy if you have a mate work the throttle). Them move the pick up plate till the flash is where you want it. As long as you've set the pointer at exactly TDC all is good.
Things with Boyer. If you start with a full 4Ah battery and your dynamo stops working you will get about 1 hours riding. When the battery drops to about 10v the ignition will revert to full advance so at low revs she will run like a pig. Just so you know.
Cheers
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I've set it the best as i could though can't see 33° BTDC more like 25°. I feel like i should have left it well alone and used it as it was set up when i got it from SRM.
At first i turned the pick up plate the wrong way and i could tell it was wrong, or so i think, and i've turned the pick up plate in the opposite direction and it's at the end of it's travel within the slot.
Must admit it seems to tick over better but i'm still not happy/convinced now that i've messed about with it. Next thing i suppose is to take it round the block a few times and take it from there though i've noticed a mysterious oil leak from one of the forks. Do i like fettling? No i don't. *problem*
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This is what BB have to say where you run out of adjustment before getting the figure you want -
Start engine and run for 4 to 5 minutes to warm up. Connect the strobe lamp and
time with the engine running up to 4000 R.P.M. This is done by moving the stator
plate on its slotted holes. If the timing is not obtainable before the end of the
adjustment, the magnetic rotor will need to be slackened off and moved a small
amount until the timing can be obtained
From (as an example): http://www.boyerbransden.com/pdf/KIT00052.pdf
If you aren't getting more than 25°BTDC at full advance, things probably won't turn out well. I know I had to fight with both of the BB Mk1V systems I have had - but thereafter they were good as long as the battery voltage was kept up.
They say their newer systems aren't so sensitive to battery voltage (so the gizmo doesn't stay at full advance if voltage isn't high enough) but I do have to admit to having retro-fitted a magneto on one of the two I had because the elderly 3-wire 90W alternator (doubled-up to 12v operation) wasn't really up for a decent halogen globe + BB sparks in low speed conditions. The other bike, I stuck with the BB set-up having fitted a newer 200W alternator.
It should be OK with a dynamo - I've seen it done successfully using DVR2s - but there won't be a lot of spare juice available. I'd think LEDs could be your friend if you're not there already?
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G'day Catz.
Groily hit the nail on the head. Pop the rotor of and move it back to give more adjustment.
Cheers
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Thank you both for your replies.
I'll have a look at it. I reckon it could be done by ear instead of that useless degree wheel from SRM.
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G'day Catz.
Don't give up mate. Once it's done right you won't need to touch it for years. Getting the TDC mark is important. One of those tools that screw into the plug hole isn't bad, I use a dial gauge. Your pointer looks a bit flimsy and will shake around with vibes. Turn the disc so it faces more to the pointer mounting and make a more solid pointer.
Both mine have the degree disc and pointer permanently fixed.
Cheers
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I appreciate what you're saying Muskie and i found TDC and used a piston stop and come to think of it now the pointer could have been bouncing around a bit/a lot.
Once i got the pick up plate adjusted it sounded like it was near the mark anyway and i'm not going to mess around with it again until i test ride the bike.
My other concern at the moment is to get this spare tank fitted and sort a dodgy left hand fork leg.