"Slow" starting issue

[bosnjo]

This issue has been largely discussed on this and on US forum.
It's all about the battery problems from the factory or the replacements that are not strong enough.
The problem occurs when cams stop on the highest compression position when you turn the engine off. In that case, the starting procedure needs a lot of CCA power from the battery. That is the reason it sometimes happens, sometimes it doesn't. It all depends on the cams position.

So, after a lot of posts, the conclusion is, the best battery cost wise:
Yuasa YTX14H-BS - 240 CCA
Dimensions: 150mm x 87mm x 145mm
1.2A, CCA 240A, 12Ah

 

[TheStammeringBiker]

Thanks all, I am aware of the "bad batch" issue which my 2019 suffered from but I'd been assured this wasn't present on the latest bikes. It defo feels like the battery isn't strong enough, but it pains me to replace it myself especially when BMW won't acknowledge there is an issue.

 

[siddo]

Anyone tried upgrading their power cables?

Starting upgrade kit

Starting upgrade kit available from Motorworks, the UKs number 1 for BMW motorcycle parts

www.motorworks.co.uk

 

[Bigcats]

Oddly this has just happened on mine for the second time in a year.

2019 still on original battery....regularly put it on a CTEK maintainer (not always though). Went for a run Sunday and zero issues.
Went to work on it this morning and it did that funny slow start and popped up a warning message (should have known then) but started.

14 miles motorway blast to work....

Started fine when I left work....13 miles home, stopped at Tesco and wouldn't start, threw up loads of errors. Left it for 30 mins and started.
Now ordered a Yuasa YTX-14H-BS 240cc but not getting here till Tuesday.
Very annoying.

 

[Engineer]

Mine started to do this about 6 months after buying the bike - if the battery is slightly low it is almost guaranteed to do it - my tracker tends to deplete the battery enough after 3 days without use and then it is pot luck as to whether or not it will start. My dealer says the battery is OK. I now keep the bike on the BMW charger when not in use, although sometimes I cannot avoid leaving it for a few days.

When I first turn on the bike, I monitor the battery voltage on the display and wait for it to climb as far as it is going to before starting the bike - if I try to start the bike when it is around 11.6 volts the problem happens - if the voltage is too low the engine will hesitate 'kick back' with a splutter and an engine fault will be reported. BMW know what the issue is but have yet failed to acknowledge it.

P.S. my bike is a 2021 R1250 GS

 

[RS-eyJohn]

This problem clearly is widespread but remains unacknowledged by the majority of BMW dealers - so I did lots of reading here and eg ABR to be sure I wasn't imagining it.

My 2019 1250RS came to me with 21,000 miles on and in 8,000 more milers since I have used the booster pack at least a dozen times...in that time I have also:
- changed battery for a Motobatt (yellow has 4 posts to make accessory connections easier) sold by Motorworks - but that has lasted only 3,300 miles and is now weakened to 12.4 V. I have been reluctant to spend mega-conga on a really big Lithium replacement battery, as I suspect heavy current drain is what's been killing the statring;
- checked all main leads for damage and breaks, cleaned and lubed terminations (battery grease) seeking an extra volt or two;
- although the starter relay has never chattered or failed, swapped it with a lower mileage s/h one from Motorworks;
- pulled the starter motor to check and clean the brushes/commutator. NB it was here that I did find a fault, that had been mentioned just once in the 40+ pages on ABR forum, of shorting between the starter +ve connection as it passes through the outer alloy case. Poor insulation provided by just an o-ring -which I suspect squashes and allows shorting when the motor kicks into life, so I added a short piece of heat-shrink tubing;
- now fitting a Yuasa YTX14H-BS - https://www.tayna.co.uk/motorcycle-batteries/yuasa/ytx14h-bs/ and getting on with closing up the patient.

Now I may be suffering from Premature Congratulation but I will be monitoring things like a hawk, and report back.
Onwards and Upwards?

 

[Mr Bean]

I've just added a Motobatt hybrid to mine, after the 4 yr old 16ah super duper Yuasa started to crank slowly.

Here's the resting voltage after being parked up for an hour - after a 15 minute journey. After a week it still shows 13.4v, never did the Yuasa one show the same level of residual voltage.



Time will tell if it continues to perform at the same level.

 

[MotoRevive]

I'm more interested in why you had three engines in one bike ???

 

[RS-eyJohn]

Have ridden another 940 miles since cleaning, checking etc work on starting, and being careful not to leave the ignition on without a running engine, delighted to report no issues, zilch, nada, no problemo.
Whilst the Yuasa 'H' series battery is rated at 14Ah capacity (2 less than oem) it clearly does provide greater instant current to get the engine turning, and that has been satisfying.

I assume (yeah, I know...) that the internal short in the starter motor was the largest problem, and is now prevented from reoccurring...
The problem I found is entirely hidden under nut '2' in this diagram:

-and only revealed when the starter motor is disassembled...no scorch marks found, perhaps because the bike's brain was quickly killing power to the starter once it saw excessive current.
Now I'm pretty pissed off that a Japanese manufacturer [Denso] would rely on an o-ring, when proper sleeving would have 100% prevented this mode of failure.

As a 'just in case' mod to make jump connection to -ve better I added a heavy brass tag to the starter Earth connection - and officially I'm still carrying the lithium booster pack around purely to help other riders...

 

[Bigcats]

I've just added a Motobatt hybrid to mine, after the 4 yr old 16ah super duper Yuasa started to crank slowly.

Here's the resting voltage after being parked up for an hour - after a 15 minute journey. After a week it still shows 13.4v, never did the Yuasa one show the same level of residual voltage.

View attachment 399765

Time will tell if it continues to perform at the same level.

Mine is still like this nearly 2 years later..... I can now use the GS-911 without it whinging at me the voltage is to low.

Just remember you should NOT leave it on charge for long periods (as directed by the manufacturer)