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TECHNICAL MOTOBRICK WRENCHING In Remembrance of Inge K. => Project Custom Motobricks => Topic started by: Doc_69 on October 16, 2014, 04:42:43 PM

Title: 1985 K75 Cafe custom
Post by: Doc_69 on October 16, 2014, 04:42:43 PM
Hi All

Today I took delivery of a 1985 K75c i bought on eBay for £300. As you would expect at that price this is no show piece. it was fitted with a fairing and screen from an RT (if anyone wants one let me know). I like my bikes the same way i like ... ...naked! im keen to get it stripped down and on the road ASAP, so this will be a 2-stage build:

1, Rough and ready with a basic seat and no paint or plastics. I just want something functional to ride through winter.
2, Once it is functioning as it should i will treat it to paint/powdercoat etc s.s fastners etc. and at that point i'll add back the side covers and a tail hump.

I have a a few projects on the go so this might be slow going but bear with me.

My immediate to-do list:
Title: Re: 1985 K75 Cafe custom
Post by: johnny on October 16, 2014, 05:15:04 PM
greetings doc_69...

welcome to motobrick.com...

there is a mod to fixt that no cluster no start issue...

j o
Title: Re: 1985 K75 Cafe custom
Post by: Doc_69 on October 16, 2014, 05:54:11 PM
Thanks J O, would you mind pointing me to that mod please. I think that will be a task for the weekend or tomorrow evening.

Here is a pic of the new gauge, can't wait to get it on.
Title: Re: 1985 K75 Cafe custom
Post by: rbm on October 16, 2014, 06:05:31 PM
Aftermarket Gear indicator/Neutral indicator board & 3-circuit Fuse block (http://www.motobrick.com/index.php?topic=6097.0)

This will give you back the start enable feature.  In the meantime, just pull in the clutch  to start the bike.
Title: Re: 1985 K75 Cafe custom
Post by: Doc_69 on October 17, 2014, 07:13:08 AM
What a Muppet! I didn't realise I could just pull the clutch. That solves the problem as far as I'm concerned. It sounds like a security upgrade to me.
Title: Re: 1985 K75 Cafe custom
Post by: Doc_69 on October 17, 2014, 06:00:41 PM
So I sorted the brakes out, the left caliper was binding and the master cylinder's piston was stuck. Both are now free and appear to be fully functional. I will replace the hoses before putting it back on the road, the top hose is pretty perished and with a rear drum I think it will be a worthy upgrade up front.

I also stripped the body work, I need to get a spring clip for one of the side panels and 3 rubbers for the tool tray the frame has a lot of surface rust but it will be bathed in WD40 until I get round to. Doing the 2nd phase of the build.

I am planning on using the stock tail section as my "cafe hump" and modifying the  original seat to fit. Let's face it, it is never going to be a sports bike so this will be more of a Cafe sofa than racer.


I've mocked it up so you can see where I am going here. One comment though, that is the heaviest tail section I have ever come across. I understand why though
Title: Re: 1985 K75 Cafe custom
Post by: The Mighty Gryphon on October 18, 2014, 08:40:35 AM
"Cafe Sofa"...

I love it.
Title: Re: 1985 K75 Cafe custom
Post by: Doc_69 on October 20, 2014, 02:35:30 AM
I only had a couple of hours to play about this weekend, so I shortened and raised the angle of the rear of the frame, keeping the stock metal. I also cut the tail piece to the correct shape. The left side panel is missing the spring clip and the mount itself is broken so some repair needed there.

Title: Re: 1985 K75 Cafe custom
Post by: Doc_69 on October 20, 2014, 02:41:17 AM
I also amputated the stock silencer, now I need to find someone who can fabricate a respectable muffler from the stump.
Title: Re: 1985 K75 Cafe custom
Post by: beachcomber on October 20, 2014, 07:07:27 AM


I am planning on using the stock tail section as my "cafe hump" and modifying the  original seat to fit. Let's face it, it is never going to be a sports bike so this will be more of a Cafe sofa than racer.

There's quite a few of us that would disagree with that statement .........here's Ben Kingham's 155mph B.E.A.R.S. championship winning bike. My road bike's not far behind with 145mph performance.

 (http://i1213.photobucket.com/albums/cc472/manfredvonheyda/IMG_2837Copy_zps71f4ae27.jpg) (http://s1213.photobucket.com/user/manfredvonheyda/media/IMG_2837Copy_zps71f4ae27.jpg.html)
Title: Re: 1985 K75 Cafe custom
Post by: Doc_69 on October 20, 2014, 07:32:19 AM
No offence intended, meant only to imply that my particular K75 is never going to be a propper sports bike.

I think the stock setup will be more than quick enough for me, I just want it to look a bit more the part.
Title: Re: 1985 K75 Cafe custom
Post by: beachcomber on October 20, 2014, 10:08:22 AM
No offence intended, meant only to imply that my particular K75 is never going to be a propper sports bike.

I think the stock setup will be more than quick enough for me, I just want it to look a bit more the part.

No offence taken - what we call tongue in cheek !!!!!!!!!!!!

That said - I saw a wicked K75 when I was out in Saxony for my summer break - very similar in appearance to Ben's bike. One of those occassions that I didn't have my camera with me. I invited him to call round our house for our annual Pig Roast weekend, but unfortunately he couldn't make it.

I really like Kay triples [ all triplea actually ] and have often said if I can get one cheap enough, I'll build it similar to my Streetfighter, but as a Cafe Racer
Title: Re: 1985 K75 Cafe custom
Post by: Doc_69 on October 20, 2014, 10:48:50 AM


I know what you mean, I like anything with 2 wheels and an engine.  I have been looking for a Brick for a while now so when I saw this one I knew it had to be mine, but my bid ceiling on any project bike is capped at £300, parts are a different story :). But all this one really needs to be back on the road is the shock (which arrives today) some inlet rubbers and and a little TLC. The rest is just plain fun factor.

Title: Re: 1985 K75 Cafe custom
Post by: thedutchrockstar on October 20, 2014, 11:54:25 AM
That's already starting to look real nice, I'll be following this build closely ;)
Title: Re: 1985 K75 Cafe custom
Post by: Doc_69 on October 21, 2014, 06:58:26 PM
 :2thumbup:
Right, so some new parts arrived today, new progressive 421, indicator number plate light bolt combos, and a cool LED tail/stop light. I have also ordered a strobe unit for the stoplight, anyone know if they are legal in the UK? I also got some bar-end mirrors, seat foam and the digital dash. The headlight, LED resistors, strap-ons and some other bits are still on order

With all the above, the parts now cost more than the bike +delivery so I need to calm down on the ordering I think.
Title: Re: 1985 K75 Cafe custom
Post by: beachcomber on October 22, 2014, 04:08:15 AM
:2thumbup:
Right, so some new parts arrived today, new progressive 421, indicator number plate light bolt combos, and a cool LED tail/stop light. I have also ordered a strobe unit for the stoplight, anyone know if they are legal in the UK? I also got some bar-end mirrors, seat foam and the digital dash. The headlight, LED resistors, strap-ons and some other bits are still on order

With all the above, the parts now cost more than the bike +delivery so I need to calm down on the ordering I think.

Just realised you are in the UK !!!

I have got the remains of 4 or 5 Kays - all 100 and 1100, but a lot of the cycle parts etc are interchangeable. Give me a shout if you need a spare wurzlegrommetvalve - I might just have one.

My pal does have some wicked 8mm Hi-Po plug lead sets for 75s. [  www.ramshox.com (http://www.ramshox.com). ]
Title: Re: 1985 K75 Cafe custom
Post by: rbm on October 22, 2014, 08:55:13 AM
Just throwing out an idea.  For the tailpiece, you may want to neglect to replace the grab handles, fill in the voids with fibreglass and do some body filling to smooth over the tail.  It changes the character of the backend.

(https://lh3.googleusercontent.com/-n_WXjccroQc/UIeChkKRy9I/AAAAAAAAB4k/wx-37sk7kDI/s800/modified%2520tail.jpg)
Title: Re: 1985 K75 Cafe custom
Post by: Doc_69 on October 26, 2014, 05:59:04 PM
Thanks beachcomber, I am slowly seeing the parts list growing every time I look at the K. So far I just seem to need frame rubbers, side panel and tank retention clips, brake hoses and inlet manifold rubbers. With a bit of luck I can take the kinks out of the brake drum rod thing without damaging the threads.

If you can spare some rubbers that support the tool box or if you have a collection of random clips, then let' discuss prices. That would apply to good inlet rubbers too :)

On the HT cables, I'll keep that in mind. First priority is to get it running again, then I'll definately look at getting it running well!
Title: Re: 1985 K75 Cafe custom
Post by: Doc_69 on October 26, 2014, 06:14:36 PM
Just throwing out an idea.  For the tailpiece, you may want to neglect to replace the grab handles, fill in the voids with fibreglass and do some body filling to smooth over the tail.  It changes the character of the backend.

Thanks Robert. My original plan was actually to build something like this

But I seem to keep coming back to hiding batteries and electronics behind plastic. One of the first thoughts I had as to smooth the hump off, but I think the handles and dimples add character that you don't seem to get on any other tail piece so I'm thinking that I might lose the handles but keep the dimples? For now though they will all stay, I'll invest time in the cosmetics when I get round to doing the full strip and spray. Thanks for the thought though, much appreciated.
Title: Re: 1985 K75 Cafe custom
Post by: beachcomber on October 27, 2014, 05:34:19 AM
Thanks beachcomber, I am slowly seeing the parts list growing every time I look at the K. So far I just seem to need frame rubbers, side panel and tank retention clips, brake hoses and inlet manifold rubbers. With a bit of luck I can take the kinks out of the brake drum rod thing without damaging the threads.

If you can spare some rubbers that support the tool box or if you have a collection of random clips, then let' discuss prices. That would apply to good inlet rubbers too :)

On the HT cables, I'll keep that in mind. First priority is to get it running again, then I'll definately look at getting it running well!

PM me a list with pix if possible ...... that's not you who contacted me on E-Bay for the inlet hoses was it !!!! ??
Title: Re: 1985 K75 Cafe custom
Post by: Grim on October 27, 2014, 08:16:26 PM
Just throwing out an idea.  For the tailpiece, you may want to neglect to replace the grab handles, fill in the voids with fibreglass and do some body filling to smooth over the tail.  It changes the character of the backend.

Thanks Robert. My original plan was actually to build something like this

But I seem to keep coming back to hiding batteries and electronics behind plastic. One of the first thoughts I had as to smooth the hump off, but I think the handles and dimples add character that you don't seem to get on any other tail piece so I'm thinking that I might lose the handles but keep the dimples? For now though they will all stay, I'll invest time in the cosmetics when I get round to doing the full strip and spray. Thanks for the thought though, much appreciated.
LT didn't use the handles. They have a filler peice that fits in place. ;)
Title: Re: 1985 K75 Cafe custom
Post by: retrorodent on October 28, 2014, 04:20:05 AM
Hi,
That looks a comfy seat, Do you want to sell it?
Chris
Title: Re: 1985 K75 Cafe custom
Post by: Doc_69 on October 30, 2014, 10:38:59 AM
Hi,
That looks a comfy seat, Do you want to sell it?
Chris

I suspect you are referring to the big sponge seat? I'm afraid that one is not mine to sell.
Title: Re: 1985 K75 Cafe custom
Post by: Doc_69 on October 30, 2014, 11:24:01 AM
Frame is now correct, a little more to do to get the rear cowl into place but it sits just where I want it.
 I have borrowed the battery from by suzuki, an 8-cell ballistic. This will live in the tool tray once I make a home for it, and get some frame rubbers.
Title: Re: 1985 K75 Cafe custom
Post by: Doc_69 on October 31, 2014, 06:38:25 PM
Super exciting day today, my strap-ons  arrived. Had one hell of a week but could not wait for all the trick or treaters to go to bed so that o could get to the garage an get them on. All went together nice and easy except that I had to loosen  the top brake hose, so now that needs bleeding. The bars look fantastic btw, but there goes all comfort factor. I'll post pics  of  the bike asap.

Re the fount brake, I would really like to run simple brake hoses with banjo fittings from top to bottom and ditch the the whole weird hose to pipe to splitter to hose to pipe to caliper business. I can't imagine that this isn't possiblebut if anyone knows what size fittings and thread pitch works I would be most grateful.

Also, anyone got any suggestions on where to position the ignition?
Title: Re: 1985 K75 Cafe custom
Post by: Doc_69 on October 31, 2014, 06:41:25 PM
Oh, here is a pic of where the battery will live, and what you also see there is my new exhaust. Some assembly required
Title: Re: 1985 K75 Cafe custom
Post by: Doc_69 on November 01, 2014, 04:39:25 AM
Also, on the exhaust, I have a baffle, some packing and a basic SS end tip. The baffle needs to reduce the noise, obviously, and give some back pressure. Anyone got any experience of regulating back pressure on an otherwise free flow exhaust!
Title: Re: 1985 K75 Cafe custom
Post by: Doc_69 on November 02, 2014, 05:35:51 PM
Right, ignore some of my previous posts, I have resolved the "where to hide" my ignition issue. And I must say although it seems pretty obvious, I think it is perfect. So far I can't get rid of that writing, so I may end up spraying this and the alternator cover.
Title: Re: 1985 K75 Cafe custom
Post by: Doc_69 on November 02, 2014, 05:44:31 PM
this was just supposed to be a quick, get ready for winter riding, build but I couldn't resist cleaning up the mid section so in addition to making the seat supports, I made a battery box and some supports for the ECU to put it under the hump at the back.

Title: Re: 1985 K75 Cafe custom
Post by: Doc_69 on December 01, 2014, 06:26:33 PM
Starting to take shape now.
Title: Re: 1985 K75 Cafe custom
Post by: beachcomber on December 02, 2014, 04:25:25 AM
That seat combo looks spot on now - good work. :clap:
Title: Re: 1985 K75 Cafe custom
Post by: cjdickie on December 04, 2014, 01:56:50 PM
Looking good.
Title: Re: 1985 K75 Cafe custom
Post by: billday on December 06, 2014, 02:39:02 PM
This may be a little late, but I did a thread on moving the ignition to the airbox:

http://www.motobrick.com/index.php?topic=3605.msg21610#msg21610 (http://www.motobrick.com/index.php?topic=3605.msg21610#msg21610)

Your project looks great, keep us posted!
Title: Re: 1985 K75 Cafe custom
Post by: Doc_69 on December 07, 2014, 05:48:37 AM
Thanks. I'll check it out. I'm not sure I actually want to put the coil cover back any more.

I did some painting yesterday.  BMW  Montreal blue. The viper stripes are 1 electrical tape width apart ☺.
Title: Re: 1985 K75 Cafe custom
Post by: beachcomber on December 07, 2014, 06:18:12 AM
Good to see you have your priorities right  :2thumbup:.... the lounge is the obvious place to display them ! Understanding Wife / partner no doubt.

Like your colour ways - I'm playing with something similar [ different colours ] to break up the main colour on my Fighter.

However, I STILL can't decide on the final colour ! :dunno2:
Title: Re: 1985 K75 Cafe custom
Post by: Doc_69 on December 07, 2014, 07:15:33 AM
I got into trouble for having them in the dining room, but I think they needed a warm spot for the night, so the lounge it is :).

Colour choice for me was easy I have a bit of a thing for dark blue and then it was just a case of choosing a BMW shade.  However, I have literally no idea what to do on the wheels. Blue and polished ally, silver, black? I simply can't decide. But I am not doing them for a while so I have a bit of time yet.
Title: Re: 1985 K75 Cafe custom
Post by: beachcomber on December 08, 2014, 04:28:00 AM
I got into trouble for having them in the dining room, but I think they needed a warm spot for the night, so the lounge it is :).

Colour choice for me was easy I have a bit of a thing for dark blue and then it was just a case of choosing a BMW shade.  However, I have literally no idea what to do on the wheels. Blue and polished ally, silver, black? I simply can't decide. But I am not doing them for a while so I have a bit of time yet.

Blue to match the tins would look classy IMO - contrast stripe around the rim ?
Title: Re: 1985 K75 Cafe custom
Post by: Doc_69 on December 08, 2014, 06:14:59 PM
Just throwing out an idea.  For the tailpiece, you may want to neglect to replace the grab handles, fill in the voids with fibreglass and do some body filling to smooth over the tail.  It changes the character of the backend.

(https://lh3.googleusercontent.com/-n_WXjccroQc/UIeChkKRy9I/AAAAAAAAB4k/wx-37sk7kDI/s800/modified%2520tail.jpg)

Like the final product RBM? The paint is a bit dark to pick up the detail but basically I filled in the handle mounts and smoothed off the recesses for the black hand cups
Title: Re: 1985 K75 Cafe custom
Post by: Doc_69 on December 08, 2014, 06:18:48 PM
Beachcomber, I think you're right, but I have a Christmas deadline in this so in reality it is going to have to wait until summer I think. I know it is going to play on my mind though. Let's see if I can hold or til then
Title: Re: 1985 K75 Cafe custom
Post by: Grim on December 11, 2014, 09:43:35 PM
That by far income of the best conversions I have seen. The planes that th tank and tail are on do not match without the side panels. Most cafe builds it just never looks right.  Yours looks right.

Can't wait to see the final assembly.
Title: Re: 1985 K75 Cafe custom
Post by: Doc_69 on December 12, 2014, 06:48:43 AM
Thanks Grim, that's very kind of you
I completely agree about the lines and that was the entire motivation for doing it this way. It is a lot of extra work, but I really want it to look like it could just have been another factory option in 1985, or a pre-production concept bike.

My self imposed deadline on getting this thing reassembled and running is Christmas which in weekend terms is only 4 days, but I still have a ton of work to do, including wiring up the digital dash and reinstating the front brakes.
Title: Re: 1985 K75 Cafe custom
Post by: Doc_69 on December 14, 2014, 12:58:06 PM
Loads more to do, but I'm holding off til after Christmas, I have a feeling that there will be an air compressor and a blasting pot under the tree this year which will make the upcoming jobs of replacing the inlet stubs and cleaning the engine a whole lot easier. So until then I might just fit the heated grips an get back to painting the house before the holiday madness decends.

The bike is far from ready to wear its clothes but I couldn't resist a little photo shoot.

Merry Christmas Y'all.
Title: Re: 1985 K75 Cafe custom
Post by: johnny on December 14, 2014, 01:09:43 PM
greetings doc_69...

this motobricker approves of your bastardization of your motobrick... its already looking yeeeeehaaaaaa...

j o
Title: Re: 1985 K75 Cafe custom
Post by: beachcomber on December 15, 2014, 05:57:28 AM
Looking good.

let us know how you get on with your comp / blast pot.

I bought a blast pot a few months ago, but haven't had an opportunity to try it out yet - everyone keeps telling me the compressor won't be man enough.

Happy Christmas to you and yours - hope Santa doesn't get stuck halfway down the chimney with that compressor !
Title: Re: 1985 K75 Cafe custom
Post by: Doc_69 on December 28, 2014, 03:17:59 PM
Blast pot + soda = fail. The compressor really wasn't up to the task. When I got good air flow it actually worked pretty well but it seemed to clog quite often. I might try glass beads or other, more aggressive media. Since the compressor isn't belting out huge pressure I think I can get away with it.

Since I have the pot now I don't see any harm in giving it a go. Next job though is to replace the inlet stubs and try to get the thing running again. I can clean bits later. I also just realised that my cooling fan is completely seized.

That's another thing on the to-buy list
Title: Re: 1985 K75 Cafe custom
Post by: beachcomber on December 31, 2014, 05:39:13 AM
Blast pot + soda = fail. The compressor really wasn't up to the task. When I got good air flow it actually worked pretty well but it seemed to clog quite often. I might try glass beads or other, more aggressive media. Since the compressor isn't belting out huge pressure I think I can get away with it.

Since I have the pot now I don't see any harm in giving it a go. Next job though is to replace the inlet stubs and try to get the thing running again. I can clean bits later. I also just realised that my cooling fan is completely seized.

That's another thing on the to-buy list

yes, this is what I've heard from other peeps who have theat set up - seems you need a really powerful compressor to do the job. The Halfords / Clarks £300 jobbies aren't up to it.

A pal of mine has used Silver Sand [ ? ] and some other stuff [ sand of some sort ] he got from a builder friend. That worked with his DIY compressor - so when the weather brightens up, I might give that a try
Title: Re: 1985 K75 Cafe custom
Post by: Doc_69 on December 31, 2014, 06:09:18 AM
I just spoke to a guy that sells all sorts of blasting media and he recommended glass bead, he seemed pretty confident so I'm going to give that a go. I'll let you know.
Title: Re: 1985 K75 Cafe custom
Post by: pdg on January 05, 2015, 11:03:41 AM
A pal of mine has used Silver Sand [ ? ] and some other stuff [ sand of some sort ] he got from a builder friend. That worked with his DIY compressor - so when the weather brightens up, I might give that a try

Silver sand (aka silica sand) and/or "building" sand as a blasting media?

Enjoy your silicosis............ And the fine if you do it on a business premises.
Title: Re: 1985 K75 Cafe custom
Post by: maxt on January 05, 2015, 03:57:05 PM
Hi I have used as media glass beads 100/200 mikrons, you have to use at least 6bar I recommend 8-10 bar  I am going to blast complete engine with covers....so no paint on it
Title: Re: 1985 K75 Cafe custom
Post by: beachcomber on January 05, 2015, 04:56:26 PM
A pal of mine has used Silver Sand [ ? ] and some other stuff [ sand of some sort ] he got from a builder friend. That worked with his DIY compressor - so when the weather brightens up, I might give that a try

Silver sand (aka silica sand) and/or "building" sand as a blasting media?

Enjoy your silicosis............ And the fine if you do it on a business premises.

Thanx for the tip :clap: ...... I'll wear a big mask and do it in the garden.
Title: Re: 1985 K75 Cafe custom
Post by: pdg on January 05, 2015, 07:02:48 PM
Personally, I wouldn't use anything with relatively high (>0.5%) silica content for blasting unless I had negative pressure facilities (to prevent contamination of adjoining land/people) and a hugely filtered and efficient pressure fed respiration system. Real crystalline silica has been commercially illegal to use for blast cleaning purposes in the UK since 1950 for a pretty good reason.......

With the huge array of "safe(er)" media available these days, I don't see the point in risking it at all anyway.

For one, crushed glass works well. It's available in different grades and is good for lower pressures (60-80psi) than glass beads because it's sharper - although you still need a decent flow behind it. It's also better than bead if you have a venturi pickup type blast system again due to the shape. Last time I bought some I paid around £10 for ~50kg (from a commercial blast company rather than a media supplier - they sold it to me at the per tonne price rather than the bag price).

Of course, if you really do want to use sand then have at it - you're far enough away from me that it won't affect me directly  :neener:
Title: Re: 1985 K75 Cafe custom
Post by: Nantucket_Red on August 30, 2015, 08:38:20 AM
*resurrection post*

I love what you did with the rear seat hump. Would you mind taking a photo of a close up of it?
Title: Re: 1985 K75 Cafe custom
Post by: analogman on August 31, 2015, 12:11:59 PM
Oh, here is a pic of where the battery will live, and what you also see there is my new exhaust. Some assembly required
Where did you get teh exhaust parts and what does the bike sound like with them installed?

Thanks!