This YBR that went to Scotland and back

[WD Forte]

TLDR:
A tale of inconclusive results and intermittent faults

In fact it went from Severn Beach to Portvollo near Stornoway and most of the way back on A roads
(cos L plates.)
https://www.bikechatforums.com/viewtopic.php?t=335846
It pissed down a lot of the time but the bike kept going
until it didn't.

It broke down near Ludlow just north of Hereford where the rider intended to stop for the night at his folks.
It stopped with 33 flashing out on the eml
33 just says 'ignition coil' on the look up table

It restarted but broke down again after half a mile
with the same error code and as it was getting late and he'd been on it all day, he rang recovery and the bike was eventually dropped off to me a week or so later.

At first it didnt start when I tried a couple of times
so I went and fetched the meter and tools and it started!
After that it would start easily and I couldn't find any obvious faults.

Hmm.. so what to do?
Code 33 suggested the coil is breaking down or has bad contacts
I removed the coil and the connectors were sound enough and the coil tested out ok on the meter but were slightly high on the primary by half an ohm.
3 ohms against a spec of 2.2-2.6 ohms according to the Hyenas manual.
The system is simple
The ignition switch is main power and supplies every device
on Brown wires at turn on.
The coil has Brown supply in in and an Orange out to the ECU where it's switched on and off by the ECU to create the sparks.
Bike charges battery at 14V when running, battery connections sound, wiggling wires and connectors and shaking bike has no effect.
Power in good, ECU pins clean and bright

It just wouldn't go wrong for me.
But, code 33 right? so maybe the coil is breaking down under use/heat so a new one was ordered from Wemoto
as a precaution.
New coil arrives I fit it and it fires up.
I leave it running for 15-20 minutes more wiggling tapping shaking etc and no apparent problems
it just keeps going.

Until........
He turns up to take it away and gets half a mile down the road when it stop with code 33
WTF?
it restarts and he comes back when it cuts out as he comes to a stop when I first see the code 33 for myself
moar wtf?

I whip the coil off and test it out of curiosity
and find it has the electrical characteristics of the CDI
coils from earlier carbed bikes
The primary and secondary coils are much lower than spec
0.5/5k against 2.5/10K
I dont like that as the primary current will be far higher
than the stock coil and could damage the ecu switching circuit over time so tell him to send the bugger back
or shell out for a pukka Yamaha one from Fowlers.

I test the original coil again but this time use some brand new meter leads and it tests out perfick.
Oh FFS! Why cant the bastard just burst into flames
then we know what to fix.
These intermittent faults can be a real arse ache to solve

One thing that had been in the back of my mind was as he took it away I recalled thinking the headlight looked a bit 'flickery' and mused over checking it and maybe putting the scope on it.
When I refitted the original coil I opened and cleaned the regulator plug and there was small amount of oxidisation on a couple of pins so I sprayed some contact cleaner in there

When it started, the headlamp gave a steadier output and he took it away with both of us wondering how far he'd get
but it took him 8 miles back to Severn Beach no problem.
he also said the headlamp seemed a bit brighter.
Is that all it was? is it fixed? dunno, hope so.

At this point I can only theorise the iffy RR contact put spikes on the power line which caused the ECU to have some conniptions.
Time will tell I spose.
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bikers smell of wee

[A100man]

ECUs /EFI - pah!

not made for real-world situations or sympathetic to emergency workarounds (bodges) - I will continue to avoid.
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Now: A100, GT250A, XJ598, FZ750

Then: Fizz, RS200, KL250, XJ550, Laverda Alpina, XJ600, FZS600

[Hong Kong Phooey]

Weird. Dirty digital signals, or low analogue volt reading yer reckon?

High drain on a circuit causes weird errors on some cars I've had, cranking after it's been stood for a while can throw ABS errors, water in filter errors, but after starting the alternator pumps in the right amount of volts into them copper veins and it's all honky dory again.

It'll work until it doesn't anyway!
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'81 CG125, '97 FZS600 : '99 CBR600F4, '09 KTM RC8

[Robby]

The original coil tested out fine (eventually). You also had a replacement coil, which worked until the bike broke down with the same problem.

There is a tendency to think something is bad because it tests out a bit different to what was expected in the manual, but in reality a coil that is well out of spec will still work just fine for ages. So I don't think the coil is the problem.

I don't know how clever the ECU is with its error codes. On analogue circuits I assume it's just measuring voltage and seeing if the voltage is outside of its parameters.

I'm also going to assume it's a really dump circuit. Voltage to the coil is out of spec, throw an error. Ignore incoming voltage, or don't have an error code for that.

Pulling this together into by guess theory. Bike is moving down the road, revs around the middle of the counter. Maximum normal electrical draw - headlight on, tail light on. Charging system can't keep up - could be alternator, could be reg/rec*. Incoming voltage voltage drops too low for the coil to transform it into enough voltage to make a spark in a full cylinder (not the same as 5000rpm with no load). Bike stop.

* Shunt reg/recs have pairs of diodes called shunts. If one of these pairs has failed the reg/rec can still make enough electricity when incoming power is low (at idle) and power demand is low. They fail completely, or just make less electricity than is needed, at higher revs. This is easier to test, it's mostly revs dependent and not load dependent.

Check the charging system.

[WD Forte]

Dunno about using diodes.
Most 3 phase bike shunt regulators use 6 diodes to rectify the AC and scr's tapped into each phase ready to dump excess power to ground in pre determined conditions.
These are controlled by a sense/switch circuit using say a zener diode to to give a reference voltage at which the control circuit switches them on/off.
A diode would conduct all time the incoming voltage is over 0.5v ish while an SCR (basically a pair of transistors)
will only conduct/shunt when it's enabled by a signal voltage at its gate.

Although the Wemoto coil worked I didn't want to use it.
Its primary resistance of 0.5 ohms would pass about 5 times the current of the stock one and the associated heat could damage the ECU switching circuit in the long term.
If it only had a few percent difference I could have
lived with that, but 500% was too risky IMO.

As I said it's inconclusive but it appears to be working OK again at the moment, but if he rings me up to say it's shat the bed again. it's back to square one.
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bikers smell of wee

[jeffyjeff]

The reg/rec on my YBR bolts up on the backbone of the frame, under the fuel tank. Not much air circulation up there. Sometime around 2010, Yamaha attached a pair of air scoops to the front of the tank. Maybe it was a style statement, but I prefer to think they did that to facilitate airflow toward the reg/rec. Still, I imagine that more heat sinks into the frame than is actually pulled off by the cooling fins, due to constrained air flow. Might be that the original OE reg/rec overheated after several long days of near continuous operation under less-than-ideal cooling conditions. just a thought.
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History shows again and again how nature points out the folly of men - BOC

[stinkwheel]

Is it a normal full DC electrical system on that bike and not one of those odd split lighting/charging systems with positive and negative earth like they use on some small hondas?

One thing that occurrs is you've tested all the upstream parts of the circuit but what are the earths like? Bad earths can cause all manner of weirdness.

A little cheap LED voltmeter wired in might be handy so you/he can keep an eye on what it's doing dynamically? You can get a PCB backed LED voltmeter for well under a fiver. You could even wire it into different circuits, like the coil feed.
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“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[WD Forte]

All relevant points but its hard to check them all
as it doesn't live with me.
He also didn't want hours (money) put into it as he wants
to sell it now and get his license.

I too felt the sustained hours of riding way outside normal use must have had some effect as it had always ran just fine prior to that.
Perhaps the heat didn't damage the internals of the RR but
compromised an already oxidised terminal so it got a bit iffy?

It uses the conventional 3 phase alternator/stator/RR setup you'll find on many if not most bikes.

It's just theories and guesses right now
If it keeps running I'll assume an intermittent RR contact
put spikes on the power line because the headlamp flickering has now stopped.
If it doesn't, back to square one.
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bikers smell of wee

[BusterGonads]

Interesting tale. It makes me feel nostalgia towards my early bikes and cars which were not dependent on computers to switch the power to the ignition coil. It was so simple to check the points gap and slip a piece of thin cardboard between closed contact breakers, and slide it out again to clean them and get maximum flow. I actually hate all the fancy nonsense that has been put on bikes and cars now. You can just about guarantee that a few years from new, the thing will be constantly going wrong and costing a bloody fortune to keep running.
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2016 Triumph Street Twin; 2000 Honda CG125; 1997 Honda Nighthawk CB250

[WD Forte]

Update:
He's been clocking up miles and not reported any running problems since I cleaned up the RR connections.
The 'bad contacts on RR causing noise/ECU conniptions' theory seems to be holding up.

Incidentally it was here cos his usual 'mechanics' told him he needed a new speedo
"Really?" says I "you sure?"
so he drops it off and a few quicks tests show the drive on the axle had failed and wasn't driving the inner cable
how could they not have seen that?

New drive unit ordered and fitted and off he goes
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bikers smell of wee

[MCN]

[WD Forte]

monkeys and spanners

I recall him telling me they charged him £40 to read the fault codes
on his SH125 scoot and still couldnt fix it !
(I can do it on a Honda in minutes with a feckin paper clip if I have to)
I got the air inlet temp sensor fault code and found a broken wire which I repaired and off he went.

Honda PGM-FI is so simple to quiz
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bikers smell of wee