BMW K bikes (Bricks)

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151Back to top Go down   K75kforkurz - Page 4 Empty Re: K75kforkurz on Thu May 02, 2019 6:07 pm

chris846


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Here's the shock too. It's a WP unit from a KTM something-or-other. I've used them before on the Madass, and before that on my K100. Back then it was a 'needs must' choice because my Koni Dial-a-Ride (never any good for me) had died (actually, it was killed) and I needed a cheap replacement. These WP units seem to be very cheap on Ebay. The best thing about them is the outstanding quality, plus they're rebuildable and very versatile. They take a standard 2 1/4" coilover spring (I use rates around 250 lb/in) and have adjustable comp and rebound, plus about a mile of threaded adjustment for ride height on the cylinder body. You can vary the oil weight (standard is 2.5 wt) to get the shock exactly right for your own needs. Plus, if you replace the nitrogen filler plug with a Schrader valve you can fill it to the required 10 bar or so with a mountain bike shock pump, using good old air, drawn free from the atmosphere. They seem to come in all sorts of combinations of cylinder length and piston rod length, and you can fit gazillions of spacers under the piston to give any sort of overall length and stroke length you want. The 'special' tools that you need to strip them aren't that special and can easily be made. 

K75kforkurz - Page 4 01112
The only real hurdle is that you have to make up a rod end bottom mounting to replace the clevis that they usually always have (WP list a rod end alternative on their fiches, but it's probs v. expensive)
K75kforkurz - Page 4 01210



Last edited by chris846 on Thu May 02, 2019 6:17 pm; edited 2 times in total (Reason for editing : illiterate)

    

152Back to top Go down   K75kforkurz - Page 4 Empty Re: K75kforkurz on Mon May 13, 2019 5:11 pm

chris846

chris846
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Back brake all plumbed up. Nope, I didn't follow my own advice and use a swivel joint. Nope, the banjo fitting was nowhere near the right orientation when I tightened the nut and olive. Yep, I just carried on winding it round until it did line up, with no mechanical sympathy whatsoever.
K75kforkurz - Page 4 04013

Plenum finished. More or less the same as the Madass plenum, 'cept I've used a lot more rivets. This was because the Madass plenum underwent a major backfire and didn't look at all well afterwards.
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The plenum installed, with the coils too. No reason for the coils being rotated 90 degrees, but this was how they were on the Madass (out of necessity to clear the frame) and I though they looked okay.
K75kforkurz - Page 4 02911
The coil bracket isn't really a bracket at all, just 2 pieces of 12mm nylon shaped to clear the bellhousing. The coils are mounted on M6 rubber bobbins - we'll see just how long they last before a coil ends up dangling by its wires!
K75kforkurz - Page 4 02711
K75kforkurz - Page 4 03110


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The Longest Lunch
    

153Back to top Go down   K75kforkurz - Page 4 Empty Re: K75kforkurz on Mon May 13, 2019 10:42 pm

charlie99

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interesting plenum chris

where did you hide the AFM ? or is it still external to that box ?


and did you still use the plastic  "velocity stacks " that usually fit inside the oe plenum ?

keep going , all really creative indeed


__________________________________________________
cheezy grin whilst riding, kinda bloke ....oh the joy !!!! ...... ( brick aviator )

'86 K100 RT..#0090401 ..."Gerty" ( Gertrude Von Clickandshift ) --------O%OK75kforkurz - Page 4 Au-log10
    

154Back to top Go down   K75kforkurz - Page 4 Empty Re: K75kforkurz on Tue May 14, 2019 3:20 am

chris846

chris846
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Not very hidden!
K75kforkurz - Page 4 03010

Yep there are some velocity stacks/inlet runners in there, but they came from a K1100 because they are straight, plus the K1100 rubber adaptors are a more convenient size for the elbows you can see on the outside. I shortened the velocity stacks to maintain the same runner length as the OE K75. This setup was a complete guess on the Madass, but it seems to work well. It picks up fine and revs out nicely (I've no need to get any more technical than 'fine' and 'nicely' on these daft projects!)


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The Longest Lunch
    

155Back to top Go down   K75kforkurz - Page 4 Empty Re: K75kforkurz on Tue May 14, 2019 3:37 am

tinyspuds

tinyspuds
Silver member
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@chris846 wrote:Back brake all plumbed up. Nope, I didn't follow my own advice and use a swivel joint. Nope, the banjo fitting was nowhere near the right orientation when I tightened the nut and olive. Yep, I just carried on winding it round until it did line up, with no mechanical sympathy.
You do realise that when you tell me to do s**t I just do it, right? Anyone need any swivels?  K75kforkurz - Page 4 44271.
Bike looking great BTW.


__________________________________________________
1985 BMW K100RT + Hedingham HUB and LL’s.
2007 HD883 Sportster. Bobbed and bettered.
1954 Royal Enfield 350 Bullet. Original.
    

156Back to top Go down   K75kforkurz - Page 4 Empty Re: K75kforkurz on Tue May 14, 2019 4:05 am

charlie99

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@chris846 wrote:Not very hidden!
K75kforkurz - Page 4 03010

Yep there are some velocity stacks/inlet runners in there, but they came from a K1100 because they are straight, plus the K1100 rubber adaptors are a more convenient size for the elbows you can see on the outside. I shortened the velocity stacks to maintain the same runner length as the OE K75. This setup was a complete guess on the Madass, but it seems to work well. It picks up fine and revs out nicely (I've no need to get any more technical than 'fine' and 'nicely' on these daft projects!)


ah ! ...that might explain it ,,,  giggles

good to see mate


__________________________________________________
cheezy grin whilst riding, kinda bloke ....oh the joy !!!! ...... ( brick aviator )

'86 K100 RT..#0090401 ..."Gerty" ( Gertrude Von Clickandshift ) --------O%OK75kforkurz - Page 4 Au-log10
    

157Back to top Go down   K75kforkurz - Page 4 Empty Re: K75kforkurz on Fri May 17, 2019 3:49 pm

chris846

chris846
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Creeping progress....
K75kforkurz - Page 4 00414
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The meeting of AFM and engine block doesn't seem to lend itself to a neat solution (assuming you've decided to eschew the perfectly well designed OE air filter housing, like a twit) so, this time I've made a sort of bobbin thing that screws into a nearby M6 hole. A cut down M8 rubber bobbin is screwed into another, M8 hole under the AFM, and together they hold it around 5mm above the engine block. The AFM is mainly located/supported by its outlet, which is a firm fit into an o-ringed bore in the side of the airbox.


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158Back to top Go down   K75kforkurz - Page 4 Empty Re: K75kforkurz on Fri May 17, 2019 6:01 pm

Dai

Dai
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Looks a pretty good solution to me.


__________________________________________________
'83 K100 upgraded to K100RS spec
Others...
'78 Moto Guzzi 850-T3, '79 Moto Guzzi 850-T3 California,'93 Moto Guzzi 1100ie California,
'03 Suzuki Blandit GSF600SK3 (NFS any more because wifey has claimed it)
    

159Back to top Go down   K75kforkurz - Page 4 Empty Re: K75kforkurz on Mon May 20, 2019 3:37 pm

chris846

chris846
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Seeing as how this Lithium Iron battery is smaller than an atom, and weighs less than a spider's kneecap. I thought I'd mount it somewhere creative.
Here's the bits of the seat support/battery carrier:
K75kforkurz - Page 4 00215

The rubber blocks are, well, just blocks of rubber. They are apparently called 'snubber blocks' and are sold by chandlers to people who screw them to boat trailers to, snub, I suppose.
I fitted them with bushes so's the seat unit could screw to them from the top (middle hole - M8 threaded) and the blocks themselves could screw to the frame (end holes - M6 clearance) The blocks slide inside folded stainless steel housings to make up an isolation mount, and the two pegs welded to the housings support the front and back ends of the battery tray, simples!
Here's what it looks like assembled, upside down naturally:
K75kforkurz - Page 4 00315

The assembly mounts onto the frame, here:
K75kforkurz - Page 4 00415

And it looks like this. There's a bit of room in case I need to uprate the battery to a two-atom size:
K75kforkurz - Page 4 00612

In the last photo you can see one of the the three frame numbers that this contraption has ended up with: two from the K1100 frames (Ronnie and Reggie) that started it all off, and, lurking somewhere, a gen-yew-ine K75 frame number, (ish).


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160Back to top Go down   K75kforkurz - Page 4 Empty Re: K75kforkurz Yesterday at 3:24 am

chris846

chris846
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Little details:

This might be a handy tip for anyone doing similar stuff (for the remaining, functional 99.999etc. percent of the world's population, this will seem stupefyingly pointless)

K75kforkurz - Page 4 00116

These started life as two normal M8 rubber bobbins/isolation mounts, as sold very cheaply by thousands of Chinese ebayers. I sawed them at an angle, rotated the halves, and glued them back together with superglue. Scientific testing by me failed to re-separate the glued join (okay, I got the angle on the first one wrong) so the end result certainly seems good and strong.

The ones in the picture were then covered with adhesive lined heatshrink to cover up the surgery - I thought they heatshrink would also help keep the two halves together, but it turned out not to be necessary.

This is all because Josef and Stefan failed to foresee the 2019 attachment of a Avon fairing to the two big holes in the side of the K1100 tank - the flanges aren't at the right angle!

K75kforkurz - Page 4 Josef11 Well excuse mir!
K75kforkurz - Page 4 Stefan11 English pillock.



Last edited by chris846 on Sat May 25, 2019 1:20 pm; edited 1 time in total


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The Longest Lunch
    

161Back to top Go down   K75kforkurz - Page 4 Empty Re: K75kforkurz Yesterday at 9:06 am

Point-Seven-five

Point-Seven-five
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Sir, your creativity and craftsmanship is somewhat awe-inspiring.


__________________________________________________
Present:
1994 K75RT
1991 K100RS

Past:
1994 BMW K75S
1992 BMW K100RS
1982 Honda FT500
1979 Honda XR185
1977 Honda XL125
1974 Honda XL125
1972 OSSA Pioneer 250
1968 Kawasaki 175
    

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