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I have just put my 2A Commando back together having replaced front and rear Isolastics amongst other things. On Friday I got it back together and it started first kick - but the AO red light didn't go out. This is supposed to go out at 12.4V so a quick check with the multimeter and sure enough, battery sits at 12.24. (It's been on an Optimate charger throughout the rebuild of the bike) I put a bulb across the two alternator wires and the bulb glowed bright in response to an increase in engine speed - so the alternator is charging. Reconnected everything and got the bike going again. Checked battery volts and discovered 11.94V on the multimeter despite engine revs. Worryingly through - the alternator wires are now quite warm to the touch!
Switched everything off again and rechecked the battery which appeared to have recovered to 12.2 V. Stumped as to what to do next I put the multimeter between battery positive (earth) and a good earth on the frame, set to 10A DC and on the 20ma scale, ignition off, and discovered a reading of 4ma. I may be wrong but I thought that this was indicative of a drain on the battery, that is to say something is taking current when it shouldn't be?
Having now reached the limit of my electrical know how, such that it is, I would really appreciate some words of wisdom as to what the cause of this problem might be. Given the recent reassembly I suspect that it will be something I have done (or not) in the rebuild?
Thankyou for your attention.
Dave
Possible duff battery
I suspected as much. The bike has been laid up longer than intended and hence battery on the Optimate longer than planned. It would not be the first time that I have had to replace a battery after extended Optimate support - never again!
Thank you for your response.
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Some anomalies here.
Yes the Optimate type of battery charger cannot be trusted, They say the voltage is HIGH and therefore fully charged when the voltage is high, but there is NO POWER in the battery. The first action when you are in this situation is to put the battery on a REAL charger where you can SEE 2A going in for 1/2 a day.
Attempting to measure current in these situations if you are NOT sure of how such current checking works it is best NOT TO.
Alternator hot wires? You do not say what your charge system is original rectifier/Zener or replacement reg/rect. The former should NOT have hot alternator wires unless the rectifier has part failed. The reg/rect system can have warm alternator wires BUT you haven't done the full alternator test as per A O Services.co.uk
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Still no success
I bought a new battery and the bike fired up first kick - and then cut out after a couple of seconds and has not started since. I have been over pretty much everything I can think of in both electrics and fuel and remain baffled. All I get is an occasional popping back when I kick it. Incidentally I also get the (AO) warning light on immediately after an attempted kick start, and then it goes off again.
I suspected the Boyer ignition unit but it appears to pass the test of creating a spark at the plugs when making and breaking a connection between the two stator leads with ignition on?
Only other relevant point I can think of is that my multimeter displays 0.3 - 0.4 ohms between battery (+ve) and every earth on the bike. It's not a lot but I would have expected this to be zero?
I would appreciate any suggestions toward solving this mystery.
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Digital multimeters....
... rarely zero properly. It's best to see what it reads when you connect the probes directly together.
Apart from that, I would jury-rig a system bypassing the main loom to feed the Boyer direct from the (fully charged) battery protected by a simple fuse. That would then tell you whether the Boyer was working. If so, start a process of elimination.
I would also consider whether your warning light is correctly wired.
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And so..
Today I ran a fused live direct from battery to the Boyer ignition box as suggested and the bike still refuses to start, although did produce quite a pop back at the end of one kick. Other than that the only sign of life was when making and breaking the contact with the battery which must have caused a spark which produced a small backfire through the carb. So at this point I am inclined to blame the Boyer box - which was on the bike when I bought it 30 years ago so has not done too badly.
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Have you got a spark??
It is of ltd usage trying to start the bike if you haven't got a spark just when you want it ie correctly timed. You do not need to keep kicking to find the spark, pass a magnet across the back of the two silver coils on the pickup plate. (This is the same function as the two magnets wizzing around inside) It must spark.
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Have I got a spark?
I can answer yes to that question. By moving a magnet across the stator coils as you suggest, with ignition on, we get a spark at the plugs.
Since my last post I became so convinced that it was the (35 year old) Boyer ignition unit at fault that I have invested in a new one, and have it fitted. But it makes very little difference. Now I get a "phut" noise at the end of each attempt to kick start, which may be down to the fact that I've had the new battery on charge since I ordered up the new Boyer box and it was fully charged this morning. It's as though the timing was a long way out? When fitting the new Boyer unit I have static timed the bike to 31 BTDC as per instruction.
Hopefully, at least the black box has now been eliminated, as has the stator coils, the rotor, the stator leads, ignition coils, plug leads and caps as all have been replaced with the ignition unit replacement.
I remain of the opinion that something I have done whilst separating the frame from the engine assembly by enough to fit the front and rear isolastics has caused the problem - but I cannot get to the bottom of what it might be?
Only other "symptom" is that I notice the I get a spark at the positive terminal when I connect the earth lead to the battery with the ignition off?
Any good suggestions gratefully received!
D
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If I understand you...
... the positive side of the battery is connected and you're getting a spark when you connect the earth lead. This obviously means that something is live even when switched off. I would connect a 10 amp ammeter between the earth lead and the battery terminal and see what it is reading - should be zero. If not, than I would start to trace through the loom, removing components till the reading falls to zero. One possible culprit might be the horn which (at least on earlier machines) is permanently live with the button earthing the other side.
One other thought: do you have an earth lead connecting the engine unit back to battery earth? Isolastics can be quite good insulators. I seem to remember a red lead attached to the top iso mounting (cylinder head) on my Commandos.
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hello, not commando. but i…
hello, not commando. but i had a battery terminal break away from inside the battery. the bike would run ok . the battery would show a good voltage. until things warmed up and vibrations kicked in and what with extra load on the battery. the bike just came to a stop. tap the terminals,off you went again.
barry
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The Monster - it lives!
Yes indeed the old Commando burst into life yesterday at the end of another long day. The problem at this eleventh hour was my own fault, Whilst setting the ignition timing (last done 28 years ago), I inadvertantly set it to the wrong mark! Once I had sussed that out she was away and sounding quite crisp. So it would seem that the new Boyer ignition box has cured the basic non starting problem and the thing would have started straight away had I got the timing somewhere in the parish, so thank you all for your patience in bearing with me throughout this epic battle. But before we go high fives all around - remember the hot alternator wires - well, they're back!
After only a few moments running with attenuator light flickering at me throughout, I noted the alternator wires were uncomfortably hot and shut it down. This morning I have removed the stator for examination - see pics (hopefully). The black bits look like something melted and the bubbling on the surface also appears heat related. Only thing I could think to test was the resistance between the two stator wires and that comes in at 0.5 Ohms. It may be nothing at all as 0.5 appears to be within the accuracy of my multimeter (see previous posts).
I also attach a photo of the rotor which looks OK to me but appears to have a piece of surface material missing? Do I need need a new rotor/stator?
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