1993 K75S Sulfur smoke from battery weirdness (!)

[zagando]

Lots to digest, guys and now I wish I had waited a bit to order the new battery (it has been shipped already and scheduled to arrive next Monday).

I have other LiFePo4 batteries and 2amp / 6amp LiFePo4-specific chargers here for my amateur radio use (as well as power outage backup with a 2000-watt inverter and two 100ah jobs). I will look into replacing the regulator as suggested, too.

Cold weather not a problem here on the South Texas coast; we have about 9 months of summer in between a month or two of usually mild winters and windy spring.

While that's great that I don't necessarily have to remove the tank, I've been thinking that if I do remove it I could strip the paint and polish It out to bare aluminum while it is off as I did years ago with my dear departed Berlina:


Since I have other bikes to ride in the meantime it's not a big deal for the extra downtime, especially if I'm going to need to install a new regulator, check the radiator and so on. I am also planning to remove the lower fairing and cut it down like I did with Berlina (or leave it off completely since it's usually hot here most of the year).

Tomorrow I'll contact Euromotoelectrics about an upgraded MOSFET type regulator; even though the Bosch battery I bought already has an internal BMS

(This is the battery coming; I ordered the last one in stock)

I just checked the coolant level and it is up beyond the MAX level mark close to the very top.

Thanks everyone for the suggestions and criticisms; all are appreciated. Getting old sucks!

--Z

 

[98lee]

I just checked the coolant level and it is up beyond the MAX level mark close to the very top.



--Z

The only place that has a MAX level mark is the overflow bottle. Congratulations, you have a full overflow bottle. You need to confirm that you have a full radiator! The only way you can do that is to move the fuel tank back and check the radiator cap under the right front of the fuel tank. Do you have proof positive that it is correct? You need to confirm this AT THE RADIATOR CAP before every long trip and AT LEAST a couple times a year!

The overflow bottle can be full and the radiator could be EMPTY!!!

 

[zagando]

The only place that has a MAX level mark is the overflow bottle. Congratulations, you have a full overflow bottle. You need to confirm that you have a full radiator! The only way you can do that is to move the fuel tank back and check the radiator cap under the right front of the fuel tank. Do you have proof positive that it is correct? You need to confirm this AT THE RADIATOR CAP before every long trip and AT LEAST a couple times a year!

The overflow bottle can be full and the radiator could be EMPTY!!!

 

[zagando]

Oops! OK; will do once I get the tank off---thanks! (Clymer said to top up at the overflow resevoir)

 

[51797]

Topping off the reservoir tank is relevant only if the radiator cap is working properly and flowing both directions as the coolant heating and cooling cycles happen. I've had several caps that would flow out but not back in. There is a BMW tool that can check this operation.

Frank

 

[98lee]

Topping off the reservoir tank is relevant only if the radiator cap is working properly and flowing both directions as the coolant heating and cooling cycles happen. I've had several caps that would flow out but not back in. There is a BMW tool that can check this operation.

Frank

Also, carefully check hose from radiator to overflow bottle for ANY cracks. With a cracked hose, coolant will go out the crack when hot and it will suck air into the radiator when it cools.

 

[zagando]

I'm waiting to hear back from EME on an aftermarket regulator; they sell one for airheads but the guy I spoke with wasn't sure for K-bikes so the tech guy will get back to me on that.

In the meantime, searching the MAX BMW fiche only shows this 14V regulator for K-bikes to 7/1993:



Now checking Kpartsholland:
for the 32-amp alternator
For the 50-amp alternator (I think this is what mine has but am only 50% sure):



I suppose either amperage model is a moot point since they're likely also 14 volt systems and I am wondering if the built-in Battery Management System should prevent overcharging in the first place?

 

[zagando]

This is what I received after my email query to the tech guy at Euromotoelectrics about the possibility of overcharging with the LiFePo4 Bosch battery and stock regulator:

 

[zagando]

Now what do I do?

The Niche brand 12V 75A starter relay arrived in today's mail so I was inspired to start working on getting the bike ready for its installation along with the new battery which should arrive early next week.

I've been wanting to remove the bottom spoiler so I removed that first. Then I removed the Corbin saddle for easier access to everything. Once that was done I checked my Clymer again for fuel tank removal instructions and did the depressurization routine #1 with the vacuum hose off the #3 cylinder and my Mity Vac.

When I got out my needle nose pliers and set about pulling the little clips on both rear sides of the tank I was horrified to see no litle tabs to enable pulling them out and off... I tried pulling and poking around with a hook shaped pointed tool, flat thin screwdriver and a few other tools to no avail.

I'm not even sure if there are those clips installed and I was tempted to consider a pry bar but I knew that would likely end in some sort of disaster so I dispensed with the thought right away.

I am stuck in the mud now wondering how will I remove the tank when I can't even lift up the rear more than an eighth of an inch?

Here are some pix I took of both sides of the rear tank mounts:




If there are clips on those posts maybe I should try to destroy them (I could replace them with new ones later)---but I'm uncertain as to whether or not they're even there in the first place. The tank is a tiny bit loose but something is keeping it from being raised so they probably are...

I'm all ears in case anyone has an idea as to how to remedy my situation.

---Z

P.S. Even my cat Rascal offered to help:

 

[PGlaves]

It appears that there are no clips. So just firmly pull up on the rear of the tank. This is not unusual for many K75s serviced over the years.

 

[zagando]

Thanks, Paul; I'll give it a try tomorrow!

 

[pauls1150]

The clips are easy to lose, and the tank usually stays in place anyway once the seat is on. Maybe there's something else "locally recalcitrant"? Once the tank's rear posts clear the holes, pull it slightly to the rear to disengage it from the forward mounting posts & bumpers. Have a look at the MAX parts fiche, pic 16_0808, to see this.
https://shop.maxbmw.com/fiche/DiagramsMain.aspx?vid=51745&rnd=10232024
And remember that Rascal doesn't have opposable thumbs, so he's about as useful as the big lump sleeping on the floor next to me...

 

[zagando]

The clips are easy to lose, and the tank usually stays in place anyway once the seat is on. Maybe there's something else "locally recalcitrant"? Once the tank's rear posts clear the holes, pull it slightly to the rear to disengage it from the forward mounting posts & bumpers. Have a look at the MAX parts fiche, pic 16_0808, to see this.
https://shop.maxbmw.com/fiche/DiagramsMain.aspx?vid=51745&rnd=10232024
And remember that Rascal doesn't have opposable thumbs, so he's about as useful as the big lump sleeping on the floor next to me...

Before I left for Harbor Freight this afternoon I went out to the garage and confirmed Paul's suspicion that the clips were indeed missing. Gave it a good tug and up it came!

At HF I got a load tester for future use as well as one of those D cell-powered pumps to transfer the ethanol-free gas from my K to my Slash 6 next to it while I work on the K.

Thanks for the reminder about pulling the tank back before removal, too. Will post a report once I've made further progress...

P.S. The Bosch battery arrived today, too.

 

[pauls1150]

Just another reminder - one of my dogs was so helpful that he'd sometimes grab a tool and walk out of the garage with it ("oh boy, a new chewie!") ... so keep an eye on Rascal!

 

[zagando]

Got the tank off as well as the old starter relay (everything looked OK inside the electrical box but I went ahead and replaced that relay anyway).

I also checked the radiator fluid and it appeared OK, too---right up to the hose neck beneath the big cap. The fluid was near the top of the big hose below the cap (about 1/3rd the way up the popsicle stick as shown). Here's some pix:



Tomorrow I'll finish installing the new battery but hold off on the rest as I plan to get some paint stripper before I polish the tank and then reassemble everything.

 

[GTRider]

Your radiator is low and should be topped up, with either distilled water or a 50/50 mix of BMW coolant and water.

As coolant warms and expands some is pushed into the “overflow” tank; when the bike is shutdown and cools, coolant is pulled from the tank back into the radiator and cooling system. If you have air in the radiator it is compressible, unlike water, and that coolant movement won’t happen. Likewise, a cracked hose between coolant tank and radiator will allow air entry and thus defeat the normal working of the cooling system. That hose being connected at the very neck of the radiator cap tells you where your coolant level should be—full up.

On that vintage bike, I’d get a new length of hose and clamps to run between radiator and coolant tank. Pretty easy to connect to the old hose and use it to pull the new hose into place.

Best,
DeVern

 

[omega man]

Your radiator is low and should be topped up, with either distilled water or a 50/50 mix of BMW coolant and water.

As coolant warms and expands some is pushed into the “overflow” tank; when the bike is shutdown and cools, coolant is pulled from the tank back into the radiator and cooling system. If you have air in the radiator it is compressible, unlike water, and that coolant movement won’t happen. Likewise, a cracked hose between coolant tank and radiator will allow air entry and thus defeat the normal working of the cooling system. That hose being connected at the very neck of the radiator cap tells you where your coolant level should be—full up.

On that vintage bike, I’d get a new length of hose and clamps to run between radiator and coolant tank. Pretty easy to connect to the old hose and use it to pull the new hose into place.

Best,
DeVern

Along with the above, a proper radiator cap with a good, intact gasket is what I have found fairly critical in this system.
OM

 

[98lee]

Your radiator is low and should be topped up, with either distilled water or a 50/50 mix of BMW coolant and water.

As coolant warms and expands some is pushed into the “overflow” tank; when the bike is shutdown and cools, coolant is pulled from the tank back into the radiator and cooling system. If you have air in the radiator it is compressible, unlike water, and that coolant movement won’t happen. Likewise, a cracked hose between coolant tank and radiator will allow air entry and thus defeat the normal working of the cooling system. That hose being connected at the very neck of the radiator cap tells you where your coolant level should be—full up.

On that vintage bike, I’d get a new length of hose and clamps to run between radiator and coolant tank. Pretty easy to connect to the old hose and use it to pull the new hose into place.

Best,
DeVern

 

[98lee]

Along with the above, a proper radiator cap with a good, intact gasket is what I have found fairly critical in this system.
OM

 

[zagando]

All the above is noted and gives me further reason to delay reassembly until I have a new hose, caps and clamp in hand. We have summer about 9 months of the year down here so it behooves me to be geared up well for our climate, too.

I've been perusing the Kpartsholland, Euromotoelectrics, and MAX BMW websites for bits and bobs like valve cover stainless steel bolts (that polish well), rubber nipples and gaskets, copper crush washers for the exhaust which I plan to have ceramic coated, OEM oil filters, motor oil, gear oil, tranny oil, tires, etc---and I'll add the radiator stuff to that list so I can make one or two large orders instead of a bunch of stuff piecemeal.

I'm looking into polishing the aluminum tank but will check with the seller I bought it from last year first as he mentioned he had done a bit of work on the tank (hence his red/ black paint job).

Btw, my Mystic Red bike was born 8/1992---ironically, the same time I was in Morocco---so I think it should have been painted Marrakech Red, eh?

The tank looks new inside and it doesn't have any leaks or corrosion like my '94 did but want to make sure I'll have the "good bones" to polish out beforehand.

Thanks again for all the great advice here, too!