WTB Fuel Tank K75S

[kiefer]

Hello,

I'm looking for fuel tank for 1992 K75S in good functional condition, the two that I have leak and cannot find anyone to repair.  Not sure if repairs are possible, anyone know if they can be?  I'm in Birmingham, AL 35223. Thanks

Keith

[sooprvylyn]

idk if you are open to it, but k100 tanks will also fit.  They are a little taller.

[sooprvylyn]

Might also be worth posting in one of the facebook K bike groups.  There are several there. I often see tanks posted in them.  I screen-shotted some that I keep my eye on here

[frankenduck]

idk if you are open to it, but k100 tanks will also fit.  They are a little taller.

A K100 tank will not fit in a K75S fairing.

[kiefer]

I appreciate the replies. I know there are some differences between the K100 and K75 tank, but I'm sure a K75 tank is out there.  I will check out some of the others sites you listed.  Thanks

[Martin]

A good specialist aluminium welder should be able to weld up the leak, however the tank needs to be thoroughly purged of any fuel residue. Failure to do so may have you going interstate to recover your tank. There are also  fuel tank sealants that could also fix the leak your local motorcycle shop may also help with a sealant or a capable welder.
Regards Martin.

[sooprvylyn]

A K100 tank will not fit in a K75S fairing.

Does the k75s fairing touch the tank or use those forward tank mounts? The fairing doesn't look like it would be an issue. I had a k100 tank on my k75c, and there was an issue with THAT fairing which I had to remold to fit properly(see red circle for the very small area that needed to be adjusted), but the S fairing doesn't look like it touches the tank at all.  Maybe it's the inside plastics that are the issue?

[frankenduck]

The K75S faring wraps around both sides of the tank.

Typical paint wear from the S faring on a K75S tank:

[frankenduck]

[frankenduck]

Aside from being sized/shaped differently, the K75 Std/C/S tank also has two prongs at the bottom front that a K100 tank doesn't have. On the standard and C those are used to mount the radiator grille. I can't remember if the S makes use of them or not.

[sooprvylyn]

Yes, I had to add those pins to my k100 tank to hold my radiator shroud on the C.  Wasn't aware the S used those mounting points too.  I figured it used a bracket mounted to the tripple.

If it doesnt use those pins, I suspect a k100  tank may actually fit the S...tho might require very minor cut away mod to the fairing in question.

[kiefer]

I'll have to check my bike. I initially bought  this bike as a parts bike for my K75C but decided it was too nice to be a parts bike. The previous owner got the bike after someone had put an aftermarket RT fairing on it. It did not come with the "S" fairing, so I started sourcing parts for the "s" fairing wanting to bring it back to an "S." I had replaced the tank on my "C" with a good tank prior to selling it. Now I have two leaky tanks. The "C" tank definitely has the tangs, I'll have to check the "S" tank but I think it does also.  I've reached out to several shops about repair but the response has been the aluminum is too thin....I don't know; thought I had read that folks that used the K75 and K100's for Ironbutt  competitions had these tanks modified to hold more petrol.

[Martin]

Heaps of K owners have had their tanks repaired it just requires a good experienced specialist welder who knows what their doing. MIG or TIG wouldn't be my choice too much heat, less heat would be required with aluminium solder/ brazing . They normally corrode on the lower edge, post a picture of the leak point.  If you can't get it welded try a tank sealant there are a few brands around.
Regards Martin.

[sooprvylyn]

A lot of people also swear by JB weld for tank repair on other bikes.  Might be a last ditch option here.

[Martin]

I had a scrounge in my welding gear and found a couple of sticks of aluminium solder I had inherited but never tried.  I have oxy welded/brazed many many moons ago but I've never tried aluminium and I handed in my bottles years ago. So I cut off a piece of .5mm aluminium and drilled a couple of holes in it and put a slit in it with a chisel. I wired brushed the aluminium and solder then cleaned it with a scotch pad and then a final clean with white vinegar. I used chefs torch to heat up the metal and the solder and proceeded to fill in the holes and the slit which went surprisingly easy. I'm pretty sure that with practice I could have done a neater job. I'm also sure that the BMW tank is thicker than .5 mm. So an experienced gas welder may be your solution.

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[kiefer]

I appreciate all the responses, thank you for going to the trouble to illustrate the repair…..I’ll keep looking. Thanks to everyone, much appreciated.

[frankenduck]

A lot of people also swear by JB weld for tank repair on other bikes.  Might be a last ditch option here.

I tried JB on a K75 tank once. Worked for about a year then started leaking again.

[Martin]

POR-15 Fuel Tank Sealer has good reviews but there are others just search fuel tank sealants/sealers. Could you post a picture of the tank where it's leaking.
Regards Martin.

[sooprvylyn]

I tried JB on a K75 tank once. Worked for about a year then started leaking again.

Yeah, probably not something I'd do on my own bike unless I was stuck somewhere and needed a quick temp solution...but I know it's an oft suggested solution in some circles.

[daveson]

If you want to use expoxy to fix a fuel tank, you want to use one that states that it's compatible with fuel.

[Martin]

Also be aware some sealants are not ethanol compatible. Does anybody know the wall thickness of a K fuel tank?
Regards Martin.

[frankenduck]

If you want to use expoxy to fix a fuel tank, you want to use one that states that it's compatible with fuel.

Good point. I made sure that I used a gas friendly version of JB Weld.

[The Mighty Gryphon]

JB Weld has a formula specific to fuel tank repair.  I believe it's called Tank Weld.  It's also used on oil pans. 

[kiefer]

I appreciate all the suggestions. If I can’t get a proper fix then I’m just gonna find another tank. That’s good. Currently I can’t post a pic as I am out of town and my bike is in storage so it could be a couple of weeks before I could actually post a pic. Thank you for all your help to everyone.