Fused solenoid? - K-Bikes.com - Excellence in Motion
 
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post #1 of 7 (permalink) Old Mar 27th, 2020, 4:47 am Thread Starter
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Fused solenoid?

I have owned my 1997 'Taxi' K1200RS since December 2004 and have absolutely loved it. In 2011 I bought a K1200S which has now been replaced by a K1300S Motorsport - which was going to be part-exchanged for a Triumph Tiger 1200, all ready for my retirement next year.

One 'last' ride told me that I was not quite ready to lose the K13, so I kept it and retired (for now) the K1200RS. It has been garaged all winter so yesterday I fitted a fully charged battery (green light on Optimate) but it would barely turn over. So I carefully jump-started it from a running car engine battery, put the seat on, ran it around the block and kept it idling until the fans kicked in. Gearbox, clutch brakes tried. All perfect.

It nagged me that it wouldn't start on a seemingly fully charged battery, so this morning I tried again, having charged the battery to full. Again it tried to turn (very sluggishly) but did not fire. So I released the starter button and turned ignition off - but the starter continued to try to turn with no ignition and without the starter button touched. So I whipped out the battery as fast as I could, feeling dreadful that I'd damaged the old girl. . .

I seem to remember reading on the old i-BMW site about this - have I melted or welded something on the starter solenoid? I would be very grateful for advice on this, and how I set about fixing it.

My plan is to still sell the K1300S Motorsport (anyone interested? In East Yorkshire, 12,000 miles, showroom condition, clutch judder and hot start fully sorted under Bowker's warranty), and to run the RS alongside the Tiger.

Update - Having read other posts, I reckon I may have fused the starter relay. Can a battery still be 'weak' somehow, despite showing green light on the Optimate?

Last edited by mcchoc; Mar 27th, 2020 at 5:13 am.
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post #2 of 7 (permalink) Old Mar 27th, 2020, 12:23 pm
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Yes, even with a green light on a charger, your battery may be toast. It probably has sever sulfation limiting its actual capacity. The green light indicates the battery has reached fully charged internal resistance. You have indeed melted your starter relay.
If you had a volt meter on that battery while you were cranking you would have observed the voltage drop below 9.5 volts, indicating a bad battery. Leaving a battery over the winter is not good, especially if it is an older one. You can even be fooled while keeping a smart charger on the bike over the winter. You think all is good but the actual battery capacity is shot and you will drop from your surface charge of 13 or so volts to some lower voltage that will not spin your starter but certainly flow enough amps to cause trouble.

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post #3 of 7 (permalink) Old Mar 27th, 2020, 1:44 pm
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That relay isn't available from BMW.All they offer now is the updated smart relay kit that needs wiring in.Rather expensive and not immune to failures.OEM on the post-facelift bikes.Won't fuse as it won't engage below a certain voltage? 12.3 I think but at lower voltages starter will still drag and start attempts may just compromise the relay and shorten its life.So later down the road the expensive smart relay will fail.

Anyway if not available from BMW or resellers, that early relay is a dumb 4-pins.So with a little rewiring could be replaced with a rather cheap and reliable solenoid.Quote? $20.00 and 2 hrs?

Btw....my smart relay did fail.Close to end of season and right upon arriving home after a rather cold/wet 7500km crossing of our continent! Some electrical hacking and a boat battery isolation switch for a "Rider powerer solenoid" kept my bike running/starting til the freeze!Fixed later but for cheapness sake I bought a complete harness w/relays on fleabag.Been a while and never spun the starter or stressed the relay with a low(ish) battery ever since but if ever it fails again a solenoid or cheap 100A relay is going in!

Benelli 50cc at 14
Yamaha RD 200 at 16
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Honda CB 750 F at 18
Honda V45 Sabre at 24
BMW K100RS at 27
BMW R100GS at 34
BMW K1200RS at 53
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post #4 of 7 (permalink) Old Mar 27th, 2020, 5:09 pm
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On these older bikes with no low voltage protection you have to be alert and stop the start attempt right away. Find a new battery. Or get a jump. I carry a lithium battery small jump pack to share on long rides.

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post #5 of 7 (permalink) Old Mar 30th, 2020, 10:36 am Thread Starter
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Thanks

. . very much to Beech and Pierre for your replies. The battery is less than three years old, but I hear what you're saying about the green light not always telling the full story. I keep forgetting that my RS is now almost a quarter of a century old. Guess I will lay the old girl up for now and when I retire next year I will try to bring her back to life with a new battery and relay. I have a pal who knows a lot more about electrics than I do. Couldn't help noticing yet again the build quality on the old flying brick - even my new Tiger looks disposable next to her. Great shame that all things are now built down to a price rather than up to a certain standard. Thanks again guys, David Mc.
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post #6 of 7 (permalink) Old Mar 30th, 2020, 12:18 pm
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BMW has a retro fit starter module with wiring harness and a direction booklet for about $230 (US) This would be a good way to go. Keeping it "stock".
61 35 7 663 945 SET: RETROFIT KIT, STARTER MODULE.
I bet with the instructions you could tackle it.
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post #7 of 7 (permalink) Old Mar 30th, 2020, 12:49 pm
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There you go....OEM type 75A starter relay.

https://www.motorworks.co.uk/vlive/S...&Filter=submit

Or Google that relay number for best pricing? That's a pretty common relay!

Bosch 0332 002 168

Benelli 50cc at 14
Yamaha RD 200 at 16
Yamaha RD 350 at 17
Honda CB 750 F at 18
Honda V45 Sabre at 24
BMW K100RS at 27
BMW R100GS at 34
BMW K1200RS at 53
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