Author Topic: Fitting a "trunk" to a 1992 K75RT  (Read 7654 times)

Offline jiggseob

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Fitting a "trunk" to a 1992 K75RT
« on: March 09, 2025, 11:36:54 PM »
I would like to fit a tail trunk to my 1992 K75 RT.  It already has the side bags which are in good shape, but I like to ride without them and a 25 litre back-case would be sufficient for my day to day errands.  The stock rear "rack" is installed over the rear fender nacelle, a picture of that is attached below.

How does a tail trunk attach to this rack, or does a tail-trunk replace this rack?
  • Round Hill, Alberta, Canada
  • 1992 K75RT with ABS

Offline The Mighty Gryphon

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Re: Fitting a "trunk" to a 1992 K75RT
« Reply #1 on: March 10, 2025, 02:31:24 AM »
What you are looking for is the Iconic 22 liter top case.  They seem to be getting rare despite the plethora of bricks that are being hacked into scramblers and cafe racers.

It has a key that locks into a plate that is put into the rack in your photo.  For some reason, there are more of the top cases than the plates.  If you find a top case, make sure it comes with the plate.
  • In my garage in Marilla, NY
  • '91K100RS White/Blue
Current:
'91 K100RS16V "Moby Brick Too"

Past:
'94 K75RT "Ilsa, She Wolf of the SS"
'92 K100RS16V "Moby Brick" (RIP, deceased in a vehicular assault)
'94 K75S Special Edition Dakar Yellow "Cheetos"
'89 K100RS Special Edition "Special Ed"

Offline frankenduck

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Re: Fitting a "trunk" to a 1992 K75RT
« Reply #2 on: March 10, 2025, 01:17:33 PM »
This bracket (Part 46542300449) attaches the BMW 22L top case to the tail rack that you have.

Once I had a Collie pup. Dug a hole and covered him up. Now I sit there by the hour. Waiting for a Collie-flower.
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Offline Laitch

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Re: Fitting a "trunk" to a 1992 K75RT
« Reply #3 on: March 10, 2025, 01:30:28 PM »
This case is hanging out in the FS-WTB-WTT section here and it comes with a mounting plate.
  • Along the Ridley in Vermont.
  • 1995 K75 89,000 miles

Offline jiggseob

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Re: Fitting a "trunk" to a 1992 K75RT
« Reply #4 on: March 10, 2025, 01:36:07 PM »
Thanks Frankenduck and Gryphon, yes, that is indeed what I'm after.  The names "BMW 22 Litre Top Case" and pn 46542300449 will be helpful in chasing it down.

Right now, flea-bay only comes up with some items in France and Italy, which affter converting Canadian pesos to Eur and shipping, might end up more than I want to pay.  But now that I know what I'm looking for, it makes it easier to find.

If I can't find the BMW 22 litre top case for a $$ that works for me, I am considering fabricating from aluminum some sort of flat plate bracket that clamps to that little rack over my tail section, then fitting a pelican type case to that.  In looking at how to do that, I was somewhat doubting whether the plastic tail nacelle is strong enough.  But now that I see that BMW does exactly that, it tells me that the tail section is strong enough to support a tail trunk of ~20 litres.  High and rearward, I would expect a BMW weight limitation for the top case of 10 kg or 22 lbs.

Thanks again.

...  And now thanks to Laitch I see Natalena's post on FS-WTB-WTS ....  indeed I will follow that up.    Thanks
  • Round Hill, Alberta, Canada
  • 1992 K75RT with ABS

Offline natalena

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Re: Fitting a "trunk" to a 1992 K75RT
« Reply #5 on: March 11, 2025, 01:28:01 AM »
Thanks for the shout-out fellow brickster's! We'll see if we can work out the shipping.
  • MST
  • 1987 K75s #0919, '05 Sportster 1200C, '21 ARGO 8x8, '24 KLR650
"Hard to beat a 10x beaver, 'specially if you're gonna work it."

Offline natalena

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Re: Fitting a "trunk" to a 1992 K75RT
« Reply #6 on: March 11, 2025, 01:28:11 AM »
Thanks for the shout-out fellow brickster's! We'll see if we can work out the shipping.
  • MST
  • 1987 K75s #0919, '05 Sportster 1200C, '21 ARGO 8x8, '24 KLR650
"Hard to beat a 10x beaver, 'specially if you're gonna work it."

Offline frankenduck

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Re: Fitting a "trunk" to a 1992 K75RT
« Reply #7 on: March 11, 2025, 01:57:43 AM »
To keep from losing the 22L top case make sure that it connects firmly to the base plate. Add washer(s) if necessary.

Instead of trying to take the mounting pin apart to add a washer you can just cut a slot in the side of the washer and slide it in.
Once I had a Collie pup. Dug a hole and covered him up. Now I sit there by the hour. Waiting for a Collie-flower.
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Offline natalena

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Re: Fitting a "trunk" to a 1992 K75RT
« Reply #8 on: March 11, 2025, 10:53:35 AM »
Nice shim idea Frankenduck. I used two wide straps of weatherstrip to snug the fit, and it eliminated any plastic rattle.
As far as load capacity, it'll carry ice and beverages for 3 riders just fine. A plastic liner bag, and Bob's you uncle.
  • MST
  • 1987 K75s #0919, '05 Sportster 1200C, '21 ARGO 8x8, '24 KLR650
"Hard to beat a 10x beaver, 'specially if you're gonna work it."

Offline frankenduck

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Re: Fitting a "trunk" to a 1992 K75RT
« Reply #9 on: March 11, 2025, 12:25:40 PM »
The 22L top case is an ideal carrier for 4th of July fireworks.

Once I had a Collie pup. Dug a hole and covered him up. Now I sit there by the hour. Waiting for a Collie-flower.
New to K bikes? Click here.
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Offline jiggseob

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Re: Fitting a "trunk" to a 1992 K75RT
« Reply #10 on: March 15, 2025, 10:34:42 PM »
My Toyota had an unexpected need of more than $1100, pretty much draining what I had set aside for tires and improvements to motorcycles for this riding season.  $1100 might not break the budget for most people, but I recently got laid-off from work, and in my early 60's too far along to re-tool in a different career, so I converted my 401k to income and vested my pension and retired.  Not as comfortably as I would have liked, but it will work, just not as much fun money.
The K75 has been with me a year, and I paid $600 for it.  It came with side-bags that needed hinges and latches re-fastened, which I have done.  I find the top-case thng to be the most convenient for just running around and doing errands.  Thus my quest for a top case.
Found one near here, the wrecker has it listed on e-bay for $275usd or $400cad.  Plus the bracket.  Firm.  I've dealt with that wrecker before, buying a fuel tank that was "clean and like new" only to install it and its rusted through on the bottom corner by the fuel tap.  Tried to get a refund or other tank, nothing. Fool me once.
My last e-bay adventure was buying a sidecover for the K75, more than 100 euro with shipping, it never arrived, e-bay global shipping verified it shipped, can't track it through Canada Customs, never arrives, 100 euro down the toilet and no sidecover.
It seems that these top-case things still bring a pretty good dollar, $250 usd and up. Fellow motobricker has one in Montana reasonably priced.  Seeing what they look to be going for, its not fair for me to ask a fellow motobricker to take less.  Shipping and tax and such ends up being like 2/3 of what I paid for the bike.
Long story short, top case worth more than I'm able/willing to pay.
So off the the shop and fabricate...  Pelican case that carried my oscillioscope when I had a job becomes my top case.  A piece of 1/8" thick aluminum plate bent to shape to fit the rear rack gives the Pelican case a place to sit.  Bolt it on.  All with stuff I had laying around the shop, so zero dollars out of pocket.  The pelican case is a small one, some 13 litres capacity.
Nothing changed on the K75; no holes drilled, no cuts or hacks, so if this pelican case does not work out and my finances improve, I can unbolt this and get a real top case.
The back of the bracket is a vertical surface, 5" high and 10" wide.  The perfect place to do like most senior citizen motocyclists around here, and plaster that surface with blue and white reflective decals like a police bike.
 

  • Round Hill, Alberta, Canada
  • 1992 K75RT with ABS

Offline Past-my-Prime

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Re: Fitting a "trunk" to a 1992 K75RT
« Reply #11 on: March 17, 2025, 11:17:04 AM »
Sorry to hear of your troubles, mate. I also "retired" early (last year) which does impact my spendiness. (which is a word, by the way: I just made it  up).

Anyway, great job on your version of the "iconic" BMW 22 l top case. I found one for $100.00 on ebay and the bottom plate came with it.

For yours, all you need now is to put a little pad on the front of it as a back rest for your passenger. Those cases come in very handy, like fill with ice & beers for example.

Best Regards
  • North Shore of Lake Superior (in my garage)
  • BRICK: 1989 K75 RT - Rocinante; NON-BRICK: 2007 F650 GS Dakar - Betty Blue

Offline The Mighty Gryphon

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Re: Fitting a "trunk" to a 1992 K75RT
« Reply #12 on: March 17, 2025, 01:53:00 PM »
That's a very nice job you did on your top case.  That Pelican case is much hardier than the iconic BMW 22 liter unit.
  • In my garage in Marilla, NY
  • '91K100RS White/Blue
Current:
'91 K100RS16V "Moby Brick Too"

Past:
'94 K75RT "Ilsa, She Wolf of the SS"
'92 K100RS16V "Moby Brick" (RIP, deceased in a vehicular assault)
'94 K75S Special Edition Dakar Yellow "Cheetos"
'89 K100RS Special Edition "Special Ed"

Offline natalena

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Re: Fitting a "trunk" to a 1992 K75RT
« Reply #13 on: March 17, 2025, 02:34:21 PM »
I'll keep fingers crossed you'll tour down to Montana sometime.  We can wrench away in the garage! Retirement is really nice at filtering down what you really want/need. Hope all goes well for you. Cheers
*shipping is ridiculous to Canada, makes no sense.
  • MST
  • 1987 K75s #0919, '05 Sportster 1200C, '21 ARGO 8x8, '24 KLR650
"Hard to beat a 10x beaver, 'specially if you're gonna work it."

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