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So, a bigger wire. Why not just put one in next time you take your whole bloody bike apart! Preventive maintenance.
 

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Yes, I supposed one could that, but why not let BMW do it when it is free and then it is their parts and labor. I do oil changes and farkles just don't strip it down for fun. Rather ride.
 

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pmorritt said:
Yes, I supposed one could that, but why not let BMW do it when it is free and then it is their parts and labor. I do oil changes and farkles just don't strip it down for fun. Rather ride.
Yes. I forgot to turn on my sarcasm indicator on that one.
 

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I resurrected this thread for 2 reasons...

1) A couple of people have recently mentioned it, the symptoms at least..
2) I just did it myself.

On the way back from the dealer (yea yea I know) :( , I turned it off outside the garage and went to restart it and two slow turns died off to nothing.. At gas stations it would be slow but would eventually fire up. Since I'm heading to Newfoundland and Labrador in a week I figured it might be the smart thing to do ;)

It's pretty easy, get a 8 or 10 gauge wire and connect it from the positive battery terminal down to the relay (red wire). YES there's a physical relay. It's located under the air box on the left side. Then, run the same gauge wire from the relay (black wire) to the terminal on the side of the starter. You do not remove any stock wiring. Just run them parallel allowing more current to travel. Yes I already have an odyssey battery that stays on a tender. Ran the bike around a while in 90 degree temps and now she refires just as quick and strong as when cool :clap:
 
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^. This is essentially what a dealer will do. The HOT START harness is run in parallel to oem wires. Method according to BMW to dealer is to measure the drop in volts from top to bottom. As the oem wire and surround get hot the volts drop to starter mimicking a low battery which is not the case. If orig wires were of a thicker gauge this wouldn't have been an issue. Typical corporate save a few pennies here n tHere and pay for it down the road. :dunno:
 

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More like: Typical corporate, save a few pennies here 'n there and have your customers pay for it down the road . . . :cool:
 

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I resurrected this thread for 2 reasons...

1) A couple of people have recently mentioned it, the symptoms at least..
2) I just did it myself.

On the way back from the dealer (yea yea I know) :( , I turned it off outside the garage and went to restart it and two slow turns died off to nothing.. At gas stations it would be slow but would eventually fire up. Since I'm heading to Newfoundland and Labrador in a week I figured it might be the smart thing to do ;)

It's pretty easy, get a 8 or 10 gauge wire and connect it from the positive battery terminal down to the relay (red wire). YES there's a physical relay. It's located under the air box on the left side. Then, run the same gauge wire from the relay (black wire) to the terminal on the side of the starter. You do not remove any stock wiring. Just run them parallel allowing more current to travel. Yes I already have an odyssey battery that stays on a tender. Ran the bike around a while in 90 degree temps and now she refires just as quick and strong as when cool :clap:
Wow...this exactly what my 2015 K1300S is doing.
My mechanic couldn’t replicate it in the work shop.
Will go back and get this fix done!
Thanks so much
 

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My mechanic read this, and looked at these wires.
He said they looked quite big and adequate when they entered the insulation, but when he followed it to the end it was a narrower gauge on exiting the insulation!
He replaced it with thicker wire and its been perfect since then.
He was amazed that BMW would have such a ridiculous wire!
 

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I resurrected this thread for 2 reasons...

1) A couple of people have recently mentioned it, the symptoms at least..
2) I just did it myself.

On the way back from the dealer (yea yea I know) :( , I turned it off outside the garage and went to restart it and two slow turns died off to nothing.. At gas stations it would be slow but would eventually fire up. Since I'm heading to Newfoundland and Labrador in a week I figured it might be the smart thing to do ;)

It's pretty easy, get a 8 or 10 gauge wire and connect it from the positive battery terminal down to the relay (red wire). YES there's a physical relay. It's located under the air box on the left side. Then, run the same gauge wire from the relay (black wire) to the terminal on the side of the starter. You do not remove any stock wiring. Just run them parallel allowing more current to travel. Yes I already have an odyssey battery that stays on a tender. Ran the bike around a while in 90 degree temps and now she refires just as quick and strong as when cool 👏
Thanks for the tip. On my 2005 K1200S (my seventh BMW with K1200 engine) I had first hot start issue this past weekend. I knew immediately what was wrong. Did not want to sit on the curb another 30 minutes for it to cool down, I walked across the street to a car mechanic shop to ask for help. I was lucky where I got stranded. They jump started my bike. I tipped them worth couple beers. They were happy. I rode back home and started opening it to add supplemental wiring harness. I've made my own complete supplemental wiring harness using 6 Gauge (4 feet) for main wire and 8 gauge (1.5 feet) for Starter relay connections and reused the starter relay connectors and the starter relay itself. Those square connectors were bitch to remove even using precision tool flat screwdrivers, but after an hour of struggle, managed to get them off. CAD$35 vs CAD $230 but I did not get new relay but used the original. I did the similar work using BMW supplied supplemental wiring harness kit 12 41 8 532 735 on one of my previous K1200GT and knew how easy is it to get to it. I again realized how small diameter wire they used to power the starter meant to crank 120cc engine and never realized it would get affected by heat. Just looking at where everything is located, no wonder the heat affecting the small poxy wiring they used in original application.....
 

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BTW: the BMW hot start kit installation campaign referenced above expired years ago, and my only local dealer refuses to work in bikes more than ten years old. F'em!

The other day I got briefly stopped by the hot start fail. Ever the engineer, I found an online wire size calculator for marine applications at: Circuit Wizard - Blue Sea Systems which allows input of voltage, load in amps, wire length, fixed or variable load, temperature rating, and allowable drop. It suggests that 8 gage wire is good for up to 80 amps for wires up to 30 feet long.

What, however, is the actual load? First, we see Euro Motoelectric sells remanufactured OE Denso starters with 1.0 Kw cranking torque at 270 amps. The calculator tells me 0 gage wire is good for up to 285 amps, constant load, six seconds, 5 feet, 105 degrees C. I doubt my K1300GT flows 270 amps, certainly not through the stock wiring. This suggests the rating quoted at EME is useless, as the wiring won't carry the current.

Next, Odyssey rates the PC680 red top battery at 520 amps in a 5 second Pulse Hot Cranking Amps (PHCA). Again, such a current may not be able to pass through the starter or ground wire back to the battery, and is out of range for the online calculator, which is limited to 445 amps through 4/0 wire. Nobody gonna install 4/0 from battery to starter.

So what are we left with? 6 gage is rated to carry 120 amps, 4 feet, 6 seconds, 120 degrees C, 10% drop. Installed in parallel it will augment the stock wire size which is, after all, enough until the bike is warmed up. I'll be getting some on that, plus connectors, heat shrink tubing and a big can of patience, mixed with elbow grease. Much as I'm fond of a fully faired bike, the plastic is a hassle to R&R.

One other thing is not addressed: current has to start and end at the battery, so verify the ground wire is close in size to the hot side wire. This is, somehow, not part of the BMW solution and I can only wonder why, unless the ground wire is big enough to begin with.

Comments invited.
 

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Well, I'll chip in with some experience. I have a 2015 K1300s MS, purchased new in October 2014. It had three issues with drive-ability that drove me nuts for a bit. Hot start was one of them. I live in Phoenix, AZ, and the ambient temp never seemed to have much to do with the issue. For me, the issue was generally that I'd hit the starter button and get a 'click-chug' and no start or turning the engine over. An immediate 2nd press would always work. Most of the time this wasn't an issue as I didn't often restart the bike when hot. But another issue caused me grief in combination.

As delivered, my K1300s was very tricky to drive at low speeds. Very easy to stall as well, and I got very paranoid to turn left in traffic from a stop. And sometimes I'd be coming to a stop, pull in the clutch and the engine would die. THAT's when the hot start issue was really annoying, especially if I stalled the bike turning left in traffic. That issue had two causes. First, there was too much play in the throttle cable. Second, I needed a booster switch to (mostly) fix the low speed drive-ability issue. After those things were addressed, no more stalling.

Back to hot start. Once I determined I likely had the issue, the bike was over a year old. I took it to my dealer (GoAZ) and they had to do an extensive (over an hour) test of the bike, taking impedance measurements I assume, in order to get me the hot fix kit under warranty or recall-related warranty. Once they confirmed it, they ordered parts and scheduled me in for a 2.5 hour service for installation. And I've not had the issue since.

It is rather unbelievable that BMW didn't incorporate a thicker wire during the production run of the K1300s.
 

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5 ft 6 gage @ $2.79 = $13.95
2 ft 8 gage @ $1.39 = $2.78
2 terminal lugs #8, 5/16 hole @ $4.29 = $4.29
2 terminal lugs#6, 5/16 hole @$5.79 = $5.79
Heat shrink tubing, 3/8 x 3" @$5.99 = $5.99
Heat shrink tubing, 3/8 x 3" @$5.99 =$5.99
Total with $1.83 tax = $40.62

I'll return one of the heat shrink bits, one pack will be enough. And I knew West Marine was going to be expensive... They didn't let (my wife, who gladly spent the dough) down. Will hope to do the job this weekend and report further. Do believe loose throttle cables will need attention as well.
 

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I resurrected this thread for 2 reasons...

1) A couple of people have recently mentioned it, the symptoms at least..
2) I just did it myself.

On the way back from the dealer (yea yea I know) :( , I turned it off outside the garage and went to restart it and two slow turns died off to nothing.. At gas stations it would be slow but would eventually fire up. Since I'm heading to Newfoundland and Labrador in a week I figured it might be the smart thing to do ;)

It's pretty easy, get a 8 or 10 gauge wire and connect it from the positive battery terminal down to the relay (red wire). YES there's a physical relay. It's located under the air box on the left side. Then, run the same gauge wire from the relay (black wire) to the terminal on the side of the starter. You do not remove any stock wiring. Just run them parallel allowing more current to travel. Yes I already have an odyssey battery that stays on a tender. Ran the bike around a while in 90 degree temps and now she refires just as quick and strong as when cool 👏

Hey, how did you connect to the cable into the relay?
 

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2012 BMW K1300S (also 1993 BMW R1100RS and 1974 BMW R60/6)
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Hey, how did you connect to the cable into the relay?
I have that question as well, as I've not yet obtained an official BMW supplementary harness ( @Meese ? ) but have looked at the relay connector without seeing an obvious or easy sanitary way to add another set of conductors alongside the OEM leads.

In fact I have this question in relation to the installation of the supplementary harness as well -- apparently that harness is intended to replace rather than augment the existing OEM harness?

Often relays have dual parallel contacts that would make this easy, but that is not the case here.
 

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I've looked through the garage and storage, and haven't yet found the supplementary battery harness. :(

Sorry for the hassle.
 

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I've looked through the garage and storage, and haven't yet found the supplementary battery harness. :(

Sorry for the hassle.
Thanks for looking!

If you think you'll come across it in the relatively near future I'll hold off on ordering one... and I'm still considering the possibility of the far cheaper approach of just adding my own few buck's worth of 8 AWG wire in parallel, which has reportedly worked for at least one other owner, if I can devise a clean connection method to the relay.
 

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The supplementary battery harness adds wires in parallel with the existing wires, which you can do yourself with a bit of work. I believe there's also an upgraded relay as well.

It does seem to work well for me, or at least it's not something I have to think about anymore.

Honestly, before I installed the harness, I had pretty good luck by switching to an Odyssey PC680 battery which cranked hard hot or cold. But the quality on those seems to have gone down, or at least they don't seem to last as long for me as they used to.

So I had the harness installed by my dealer before a big ride, then remembered that I'd already bought one and just hadn't installed it yet...

If it does turn up I'll post here, as I'm sure somebody can use it.
 

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My next door neighbour has the same hot start problem with his FJ1300. Looking at the clutch problems that Suzuki had and the various brand recalls, BMW isn’t on it’s own with these issues
 
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