ignition switch problem, I think

Hi all, how are you? I have a problem I think it's to do with the ignition switch, but seeing if anyone has any other ideas before I buy one.
Putting my 1973 750 Commando Roadster, with Boyer ignition, back on the road after 10 years, bit of problem with the ignition. When I switch it on, all good and sparks, good. But when I put the switch onto the lights on position, I get a burst of sparks on the spark plugs. I have removed and sprayed the ignition switch, opened both the handlebar switches and wd40 them and cleaned them, but still the same. With the plugs out and connected, switch on normal start kick over beautiful sparks. Put onto lights and sometimes gets a burst of sparks for a second or so, then it stops. Same if I move any of the light switch positions, eg Hi to Lo, indicators etc, I get a burst of sparks on the plugs, for a second or two.

Now the obvious thing I am thinking of is the ignition switch. Followed all wires and check connections are clean. But anything to do with the lighting I get a burst of good strong sparks on the plugs. I haven't actually started the bike up yet, just checking I have sparks and a carb that works.

What do you guys think? Is it the ignition switch or elsewhere you can think of please?

Cheers

Ed

Welcome to the forum Ed.

A Boyer producing multiple sparks can be a symptom of an intermittent or high resistance electrical connection, so it most likely it is the ignition switch if it only occurs when it is set to the ignition and lights position, but I suggest you also double check there is a good earth return from the Boyer box and coils back to the battery. You could try connecting an additional temporary jumper wire between terminals 1 and 2 of the ignition switch and then see if the problem goes away? If it does, then the switch is likely to be the cause of the problem.

http://www.boyerbransden.com/faultfinding.html

I Have Continuous Sparking Without Cranking The Engine
A poor battery with a battery charger connected or one or more bad cells. A high resistance in the wiring circuit or earth return. Check that the engine is earthed back to the frame and battery circuit. Plastic coated frames must have a good earth return to the engine case. A wrong type of ignition coil with a very low primary resistance, this will draw a very high current and produce a large volt drop across the wiring. The unit will keep turning on and off generating a chain of sparks.

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Cheers L.A.B., I'll try tomorrow and over the weekend and post the results. If not as simple as earthing, which it coudl be having being laid up for over 10 years in my garage, I'll try take the ignition switch apart and see if the contacts are shorting sopmewhere.
Thanks again
Cheers
Ed

OzT said:

I'll try take the ignition switch apart and see if the contacts are shorting sopmewhere.

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Probably an intermittent contact as sometimes they get a bit mucky inside. ignition-switch-fix-t14445.html#p173613

Oh and I like the idea of the jumper between 1 & 2, cause I have tried removing number 2 but then get no sparks at all then, so I guess all 4 terminals needs to be connected.

OzT said:

Oh and I like the idea of the jumper between 1 & 2, cause I have tried removing number 2 but then get no sparks at all then, so I guess all 4 terminals needs to be connected.

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A 1 - 2 (brown/blue to white) jumper bypasses the internal switch connections for 'ignition on'.

To bypass the switch for "Ignition and lights" connect all four switch wires together.

Well I think I have removed the ignition switch from this problem. Have joined 2 3 and 4 into a common block, away from the ignition switch, as soon as I bring 1, the brown/blue live to the connection block all lights comes on as expected, but unfortunately I also get a burst of spark on the plugs.
I've removed and cleaned the earth connections onto the frame, removed and cleaned the handlebar switches: where I discovered I need 4 new screws to hold the brake lever on as they were corroded with circles where the slots should've been, required chiselling off.
So I guess it must be wiring or something else, more ideas please? The bike was put in the garage running 11 years or so ago, so I think I can rule out the wrong coil.
Or can a coil fail in 11 years just sitting there?
Thinking it must be to do with the lighting circuit though, as when l turn the ignition switch on position 3, normal ignition, I get sparks only when kicking it over. When on position 4 I get bursts of sparks.
Will work thru this page http://www.boyerbransden.com/faultfinding.html you gave me to see if I can find more clues.
Cheers
Ed

Try running an earth/return wire from the Boyer box (red) directly to the battery(+)?

If that doesn't cure the sparking, try connecting the Boyer box white wire directly to the battery(-).

OzT said:

Thinking it must be to do with the lighting circuit though, as when l turn the ignition switch on position 3, normal ignition, I get sparks only when kicking it over. When on position 4 I get bursts of sparks.

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Is that with the headlamp switched ON or OFF (at the toggle switch), or doesn't it make any difference?


The extra electrical load from the headlamp could perhaps be causing the problem if the battery is not in good condition.

According to the Boyer fault finding sheet:

I Have Continuous Sparking Without Cranking The Engine
A poor battery with a battery charger connected or one or more bad cells.

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Hopefully we are not talking about an 11 year old battery. Remove and clean up the positive ground contact areas at battery and especially at the frame . A poor earth can eventually kill the trigger diode in the Boyer's black box which is encapsulated ,not repairable.

Hi
check the battery under load, switch the lights on and check the voltage at the battery, a fully charged battery should show over 12.5v if not the battery is definitely suspect. Take it to a store and have them load test it.
Check the obvious things first as they say!
JohnT

Thanks for all the hints guys! No not an 11 year old battery, taken off my K75 that I have just sold. Not able to do anything this weekend due to a platinum double D blonde, but Monday back on the case! Well ok, maybe dreaming of the double D platinum blonde....
Cheers guys, I will get to the bottom of this!!!

Hi guys, how are you, hope you had a good weekend?

Thanks for all the advice and tips, have cracked it, and it was the back to basics, finally pinned it down to the fuse holder. Well I think so anyway, think the small spring has given up after 11 years in there. Need to purchase a 12v 10 AmpH battery and a good fuse holder. seems the battery I kept was the old K75 battery, not the new one I brought. Drat!!!!

So here's my plan to get the bike on the road, any comments or tips welcome.

1: Get new fuse holder and battery
2: Have a Mikuni carb. The chrome slide has a bit of rust. Intend to polish it off and reuse.
3: Any suggestions the best way to clean the carb body and jet from possible petrol deposits? I think there may be deposits in there as I didn't drain it before storage and all petrol has evaporated, so I am suspecting that may have left some deposits.
4: Fill tank with oil, 20/50 or would 10/40 do? whilst kicking it over now I can hear air suction so I reasoned the oil pump's working.
5: Bike had belt primary drive, which I renewed 11 years ago and about 5 thousand miles. I also have a spare new unused one. But the old one should still be good you think?
6: Drain, refill and bleed front disc.
7: Work out TDC using welding rod to put the timing degree plate in the primary chain case, old was was broken and mostly missing.


Well I think once I have done that, put some new petrol in it should start. Never moved the trigger rotor so timing should be as it was.

Think I have missed anything out?

cheers

Ed

Chrome slides rusting? Where did the chrome go?

Dave
69S

Yeah the chrome on the slide has worn at places and there's now rust in its place, I don't know how as it was alloy underneath! But intend to just polish it off and then clean rest of carb and jets of any residue petrol deposits.

Question about the battery, should be 12v 10ah, if I get a 12v 11ah, because it's cheaper, that wouldn't be a problem would it? Doesn't it means that it''ll just never get fully charged, only up to 10ah, which I think is what the initial specification is?

What I'm saying is, if chrome is missing from the slide, it must have gone into the combustion chamber. I remember someone made chromed slides for the Amal, and they stopped because of that issue. Personally, I wouldn't use chromed slides.

As far as your battery, a 2AH will work to start the bike, it just may not hold the lights too good while idling. I'd get the largest AH you feel comfortable with. I think mine is only 8, but I don't drive it at night.

Dave
69S

Cheers for that DogT, no I think I am ok with the missing chrome, that happened when the bike was off the road from standing there so I think it's ok.

As to the battery, I'll get the best price branded battery then and not over worry about the amps, rather a good steady battery than a high spec low quality one I reckon.

Well I'm excited. no haven't got the bike going yet but put the new battery in today and bypassed the fuse holder and no more of that unwanted sparking problem. Thanks all for all your help and advices.
Even better fiddled a bit with the wiring and switches and all electrics works, lights, indicators, horn and stop light. Put most things back together, cleaned the carb best as I can with white spirits and put it back on (tight fit those Mikunis with air filter), 20/50 in the tank and kicked bike over with plugs out and can hear gurgling, hope that's the engined getting primed and oil returning, not just an air lock. I think all's ready now, just need to get some fuel, put the fuel tank back on, hopefully get it done this weekend but as a ban holiday weekend may not get time to go in the garage, and be ready to see if she fires up! If so then just a few more bits like new brake fluid, clean rust off disk and seat on etc and she'll be ready for hwer test, and hopefully on the road in the next couple of weeks!

Thanks again all for the clues about that sparking, thought I may have been in for some expenses!

will keep posted how goes after this.

Cheers

Ed

OzT said:

Well I'm excited. no haven't got the bike going yet but put the new battery in today and bypassed the fuse holder and no more of that unwanted sparking problem. Thanks all for all your help and advices.
Even better fiddled a bit with the wiring and switches and all electrics works, lights, indicators, horn and stop light. Put most things back together, cleaned the carb best as I can with white spirits and put it back on (tight fit those Mikunis with air filter), 20/50 in the tank and kicked bike over with plugs out and can hear gurgling, hope that's the engined getting primed and oil returning, not just an air lock. I think all's ready now, just need to get some fuel, put the fuel tank back on, hopefully get it done this weekend but as a ban holiday weekend may not get time to go in the garage, and be ready to see if she fires up! If so then just a few more bits like new brake fluid, clean rust off disk and seat on etc and she'll be ready for hwer test, and hopefully on the road in the next couple of weeks!

Thanks again all for the clues about that sparking, thought I may have been in for some expenses!

will keep posted how goes after this.

Cheers

Ed

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Hopefully not too remedial here; you mention pouring oil into the tank. Had you drained the eleven year old oil, or was the tank just dry? Make sure you drain the crank case, if you haven't already. That 3+ litres you poured into the oil tank will make quite a mess if the sump is also full oil oil, and it returns it to the tank!

After over 11 years laid up in various garages, lean to's or just plain outside, finally got the bike started!! YAY!!! Still got heapsa little things to do to it, but can see a summer of Easy Rider (Chessington branch) happening!! Like a bat out of hell ...ha ha ha!!!!

And thanks Nater but no, it's new 20/50 I stuck in cheers!

(a little later) Damn now can't get it started again, been running for about 25 minutes, but rest my legs and try again maybe tomorrow.

Ah the trials of an idiot... me!
Well I thought the bike had ran out of petrol when I got it started over the weekend and then it stopped. so today I put some more in, kicked about 4 or 5 times, dead. Takes the plus out to see if fuel's getting thru, which it was, but no sparks!!!! Off comes the tank again, check the loom and connections. I had trouble with the ignition switch as well as the handlebar switches before, so off them came, check. Still no power. Have power out the switch where it disappears into the loom at the connectors, but nothing coming out where it feeds into the ignition (running Boyer). All other electricals works but no power out the loom into the unit. now this will make you laugh, or hopefully at least chuckle. Noticed the wire out the loom that goes into the white of the Boyer unit is not white as I first thought, it's white and yellow. Vaguely remembered years ago that was the engine cutoff switch colour.... hmm, ignition on flick the cutoff switch a few times and gets a spark. Then painfully it dawned on me why the bike had stopped running, when I was working the throttle whilst crouching down by the carb, I had accidently nudge the switch to engine off!! So 3 hours today part stripping the wiring was due to my idiotic hands!! Put tank back on, connected all bits and pieces up, fuel on, bam off she starts! I bet you nobody else have ever been that stupid as I have been!!!!

Now a few questions I wonder if you guys can help with or some advice: bike's a 73 750 with Mikuni VM34 carb and Boyer ignition, and bear in mind I have a screw driver and hammer, with maybe a pair of pliers somewhere in my tool kit so no fancy electrical tools.

1) Looking in internet for tickover speeds I see people talking between 750-900 rpm. Mine ticks over about 1200-1300 according to the tacho, but any lower it splutters and stops. Is 1200 too high?

2) The air screw on the Mikinus's quite stiff, but I seem to be about 3/4 turn out from stop. Looking on web again see difference from 1/2 out to 1 1/2 turns out. Where do you think it's a good start point?
The bike ticks over lumpily and revs quite well in netural, not able to actually get the bike on the road yet. When held at 4,000 it does pop and bang a little bit. Does it sound like I'm maybe running a bit rich? The plugs, from 11 years a go when I used to run it regular, are a little black but the tips looks quite healthy brown'ish black. And if so I guess screwing the air screw out will make it weaker?

3) Don't think this is a problem, just curious. The ignition light doesn't come on in the 3rd position, just ignition on. But I do get a spark. However if I put the indicators on it flashes in time, or if I kick the bike over a few times then it comes on. If I switch to position 4 ignition and lights on, then the ignition warning light comes on. With engine running at tick over if glows a bit but goes out when revs rises. Do you think it's something I need to look furthur into?

Thanks for your patience and help

Cheers

Ed