Big pile of dogshit

[Pukmeister]

Here's my thought on it, entirely speculation:

With a low insulation value between +ve and ground at the starter casing, it could track across when the starter relay contacts close to power up the motor windings, thus dragging down the starter voltage? Its not a direct short to ground as you describe but a current leakage across a poor insulator ?

The symptoms I have are typical, with intermittent hot starting problems that cause slow cranking and starter motor stall when hot typical of a flat battery yet the battery checks out fine and starts the bike again once it has cooled down. If a booster back is used during difficult hot starting, the extra power delivery available starts the bike as if nothing is at fault. The fault is caused by the action of heat.

Such a simple circuit, its only a battery, cabling, a high-power starter relay contact and a motor bolted to ground yet something is amiss ?

 

[Bigcats]

Here's my thought on it, entirely speculation:

With a low insulation value between +ve and ground at the starter casing, it could track across when the starter relay contacts close and power up the motor windings, thus dragging down the starter voltage. Its not a direct short to ground as you describe but a current leakage across a poor insulator.

I've found an 01 starter on Ebay so will be awaiting your results with interest

 

[Victor c]

I’m puzzled by “slightly shorting”.

It either is or it isn’t making contact.

If it is, it can be making a bad (or high resistance) contact or a good (no or very low resistance) contact.

If it isn’t, then the resistance is very high (megohms for example) but this could be compromised by eg a drop of water causing a track to ground. This could discharge the battery, but slowly, I guess.

You only have to touch a battery to earth with a spanner to see what a starter battery can deliver if it is shorted. Wear safety glasses.

Even a not-very-high resistance contact in the connections between battery and starter motor will seriously deplete the starter power, but the battery voltage will not be abnormal.

This can be caused by carbon buildup from the brushes, metal swarf, moisture, wear or poor build quality. Depending on where the starter motor rests after cranking the engine, it may or may not present a short or current drain.

 

[Pukmeister]

This can be caused by carbon buildup from the brushes, metal swarf, moisture, wear or poor build quality. Depending on where the starter motor rests after cranking the engine, it may or may not present a short or current drain.

That would be true, but for the fact that the starter motor turns when hot into a different position, plus the failed start atempts would be unlikely to put the starter motor in the exact same position each time.

Another thread suggests starter gears inside the engine casing that bind when hot, but again this fault doesn't happen at every hot start attempt (although it does always crank more slowly when hot).

 

[Pukmeister]

Just had an unexpected message refunding me for the replacement battery I had on in order, so bit the bullet and ordered a very expensive Motobatt Hybrid battery from Motorworks, at least I can trust them to have stock and it should be more than capable of supplying enough amps to crank the bastard. Looks like I’m an early adopter of new technology with this battery, I hope it lives up to the hype.


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[TIJ650]

Just had an unexpected message refunding me for the replacement battery I had on in order, so bit the bullet and ordered a very expensive Motobatt Hybrid battery from Motorworks, at least I can trust them to have stock and it should be more than capable of supplying enough amps to crank the bastard. Looks like I’m an early adopter of new technology with this battery, I hope it lives up to the hype.


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Been curious about this little guy. I’m presently running a JMT lithium and heard horror stories about charging sub zero etc. Apparently can go on fire if you’re a nob and keep charging over winter - especially leaving plugged in. Not sure if true, but certainly don’t want to test theory

 

[Nin]

Yesterday’s job was replacing the battery/starter motor cable and solenoid in my K1300GT.

They suffer the same ‘hot start’ issue, and BMW produced an additional cable to solve it.

The OE cable looks like this


The new cable is much more substantial

 

[TIJ650]

Yesterday’s job was replacing the battery/starter motor cable and solenoid in my K1300GT.

They suffer the same ‘hot start’ issue, and BMW produced an additional cable to solve it.

The OE cable looks like this

View attachment 320582
The new cable is much more substantial

View attachment 320583
View attachment 320584

Forget the cable, I’m more interested in those dapper boots you’re wearing!!??

 

[SBD]

This can be caused by carbon buildup from the brushes, metal swarf, moisture, wear or poor build quality. Depending on where the starter motor rests after cranking the engine, it may or may not present a short or current drain.

I don’t think so.

I wasn’t referring to the brushes, but to the “o ring insulator slightly shorting” in a post on the previous page. I think short circuits are digital, a bit like dead - it is or it isn’t. Though of course there could be a high resistance track, perhaps due to contamination, that could drain the battery - though this would be consistent - it would keep doing it, and it would get worse with longer time since a recharge, or there could be an unexpected resistance in the starter circuit, but again, this would be expected to be consistent, happen every time, and the issue we are all seeing is very definitely intermittent.

The current that the starter motor draws is huge. The 300A no load mentioned above does not surprise me. That suggests the motor resistance is of the order of 12/300 = 40milliohms. You’d be hard pressed to differentiate that from a short anyway. It is not a current drain unless the button is pressed.

Turning to your comment about brushgear, If there were carbon dust in the commutator segments, I suspect it would simply be blown / centrifuged / burned away, unless there were something sticky (eg, oil, grease) to retain it. DC motors are very common and well known, and generally last for ever, so I really doubt this is the issue. There certainly should not be metal swarf in a new bike’s starter motor. Moisture would evaporate, as they get pretty warm.

None of us can say one way or the other re build quality, let’s face it, if the bloody things started properly, we wouldn’t be discussing it!

 

[Nin]

Forget the cable, I’m more interested in those dapper boots you’re wearing!!??

30 yr old rigger boots.


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[Santa-2512]

Similar to what i did myself
on my 06 hexhead when it had hot starting issues.
I did both +Ve & -Ve though

It provided a short respite, ultimately the poor hot starting returned,

Root cause was the starter solenoid
And they are not a replacement item

Only fix was a recon starter, normal service resumed

 

[Santa-2512]

30 yr old rigger boots.


Sent from my iPad using Tapatalk Pro

They are no longer permitted in certain workplaces, not banned, but certainly out of favour

Use to be the boot of choice,

 

[TIJ650]

They are no longer permitted in certain workplaces, not banned, but certainly out of favour

Use to be the boot of choice,

They say that one in 7 guys have a foot fetish. I haven’t known any.
Anyway, as getting older - I have a boot and glove fetish. Probably cause hands and feet size are the one consistent. I like Red Wing and RM Williams in street boots and Daytona’s for the scooter!
Incase you care?! Lol

 

[Nin]

They are no longer permitted in certain workplaces, not banned, but certainly out of favour

Use to be the boot of choice,

Yep - that’s why I have them in my garage, they were verboten at work.

 

[Nin]

They say that one in 7 guys have a foot fetish. I haven’t known any.
Anyway, as getting older - I have a boot and glove fetish. Probably cause hands and feet size are the one consistent. I like Red Wing and RM Williams in street boots and Daytona’s for the scooter!
Incase you care?! Lol

That reminds me, I have a pair of Redwings I need to sell

 

[TIJ650]

Just had an unexpected message refunding me for the replacement battery I had on in order, so bit the bullet and ordered a very expensive Motobatt Hybrid battery from Motorworks, at least I can trust them to have stock and it should be more than capable of supplying enough amps to crank the bastard. Looks like I’m an early adopter of new technology with this battery, I hope it lives up to the hype.


Sent from my iPhone using Tapatalk

It’s been a lengthy thread and apologies for any duplication, but I’d take starter motor out. They are quite tight through frame, but do come out (watch attached - if not already seen). Clean and grease all terminals before your trip and probably you’ll be fine.

 

[Morety]

I had very similar symptoms on one of my Aprilias and it turned out to be the starter motor solenoid and under-gauge wiring (c/w corroded terminals). I replaced it for £27 with one capable of delivering much higher amperage and problems all went away. Was always fine cold starting but used to struggle once the engine was warm.

 

[Pukmeister]

I have a brand new starter relay and a good used 2021 starter motor to fit, along with the new hybrid battery when it arrives. Not much else to it so if that doesn’t resolve the starting situation it’s back to BMW for diagnosis.

 

[TIJ650]

I have a brand new starter relay and a good used 2021 starter motor to fit, along with the new hybrid battery when it arrives. Not much else to it so if that doesn’t resolve the starting situation it’s back to BMW for diagnosis.

Not your first rodeo - so sure you’ll know those things get better with miles when loosen up a bit. Another 10k and it’ll all make sense. Good luck with trip

 

[Victor c]

This guy has an interesting set of videos on the starting issue. Check out this and previous ones