This came home on the weekend, 23,289 kms and built in March of 1990:


As usual lots of cleaning and general loving to - hopefully - get it to something resembling this:

This one might be on-going for a while as my Missus was extremely patient during the first K reno but will be expecting more work done on the house while this project unfolds.  

Would love to see the end

Also would be nice to see this muffler on it, from the R80ST/GS 100GS;




https://www.google.nl/imgres?imgurl=https%3A%2F%2Fwww.capitalcycle.com%2Fassets%2Fimages%2F18122302010a.jpg&imgrefurl=https%3A%2F%2Fwww.capitalcycle.com%2FComplete-Exhaust-System--R80GS-Black-Chrome_p_4672.html&docid=P31Z_vmJTMzSxM&tbnid=dvcrse55NaaHmM%3A&vet=10ahUKEwig8N-CquvkAhXMy6QKHWCMC0gQMwhIKAMwAw..i&w=750&h=562&bih=1005&biw=1920&q=r80gs%20muffler&ved=0ahUKEwig8N-CquvkAhXMy6QKHWCMC0gQMwhIKAMwAw&iact=mrc&uact=8

Thanks Arlina, I'm definitely planning on modifying the exhaust.  I can get this silencer locally:
I know nothing of the science of exhaust systems, and its obvious that Akropovic makes a lot of money because it is a science, but I'm hoping this can be made to work.  It is off of a 450 KTM.  I can live with the sound changing somewhat but the last thing I want are loud pipes.  Also, would this can develop enough back pressure to prevent any harm to the engine?

This muffler comes from a 1-cilinder bike, dunno what sound it will give.
I know the original exhaust is the best, for sound and performance, with a bit of help from an axl grinder and some welding it should be possible to place it high on the bike without being too big.
Haven't got examples of that configuration, just slipped my mind

looks a good project ..to happen

I think so long as you keep the original headers & collector, you can't go too far wrong. If possible, the link pipe from the collector to the can should be close to the original diameter too.
I hear lots of mention of 'back pressure', but afaik the header length & diameter are the only things that have the potential to mess up an engine, and this obviously isn't an issue with keeping the stock header. The silencer just, well, silences - as much or as little as you want. IMHO you can't usually beat a stock pipe for performance/noise reduction. A meaty sound and a hole in the midrange before the (same amount of) power arrives (much more sharply as a consequence) does work wonders on the brain though (and I'm talking about mine too).
A Graham Bell's book 'four stroke performance tuning' is a straightforward read, and a bit of a bible.

I'll have a look for the book, should be an interesting venture into something I know squat about. This will likely take some experimentation on my part to find an acceptable noise level while reducing the size and location of the silencer.  Lucky for me I 'know a guy' who has a shop that does custom stainless, and now titanium, performance exhaust systems. I'll be getting him to bend the pipe from the collector to the silencer.  

First things first though - I have a gas tank to clean out.    It could be worse but I still have my work cut out for me.  Current plan (hah!!) is to get the bike running and then go about systematically (very loosely speaking of course) modifying it.

It's possible to devise a link pipe in your shed: stainless tube bends - 15', 30', 45', 60' can be bought for £notverymuch on oohbay, along with tubing chosen to slide inside it. Slit the ends of the bends and use jubilee clips to clamp them to the tube. You can play for hours, getting things to line up exactly as you want, and then just take the 'finished' article to your welder pal.
Much more time consuming!

I believe I might be in the midst of what Douglas Adams refers to as "the long, dark teatime of the soul" - at least my own version of it -  a project bike in the shop (shed) and too many pressing responsibilities to be able to spend time with and on said project bike.

I've been alternately buying parts and cleaning the gas tank.  I think cleaning a tank is another one of the great K rites of passage, similar to changing the ceramic seal on the oil/water pump.  

A few questions:  can rad hoses be reshaped?  

The "cheap bastid" part of me would like to use an original RT hose but reshape it and send it through the hole in the cover.

Next question:  this K75 came with ABS1, including a brain replaced under warranty.  One of my goals with this build is to get it as light as is reasonable so I will be removing the ABS.  Removing it should be fairly straight forward but I would like to re-install it on my '85 K100 as it would be quite beneficial on the big fatty I think.  Swapping the front end and rear wheel, etc. should be fairly straight forward but the wiring loom is a bit more of a challenge.  Why BMW chose not to just add an auxiliary ABS loom is beyond me but would it be feasible to remove this section from the K75 loom and add it to the K100 loom?  I know that I have to swap the bread box as well.

With regard to the front end I found that the Honda Transalp has 41mm forks and the length is good with twin discs so it makes for a good front end.
I tried the upside down forks from Suzuki and Kawasaki but lock to lock is very limited where the Honda gives the original lock because you use the standard triple tree.

In my own limited world, there is no known solution to 'coughing up and paying for the hose-with-a-kink that is specific to the slim jim rad on the K75s'.
Many have tried (actually just me) and just as many (always me) have failed.
The offset between rad and crank cover is just too ding dong close*

As for grafting an ABS loom onto your K100, I've never done this.
However, I have done the opposite 
Ergo it is possible. It is also a several cups of coffee, decent radio station, what else would I be doing with my life, kind of a job.

*you could always fit a standard width rad off any K100 or a K75anythingelse.

Those radiator hoses are virtually eternal.  I would check on ebay for a previously enjoyed hose for cheap.

https://www.ebay.com/itm/1990-1991-1992-1993-1994-1995-BMW-K75RT-K75-RADIATOR-WATER-HOSE-HOSES/133176080231?hash=item1f01e9b767:g:AyEAAOSwAVBdgmBiUPSGround!14052!US!-1

Woodie wrote:. . .  can rad hoses be reshaped?  

The "cheap bastid" part of me would like to use an original RT hose but reshape it and send it through the hole in the cover.

Let that bastid run free! There's this to try.

I'm with Arlina on that Exhaust, would be a treat to see. Dual radiators? $1500 for new K1200 twin radiators and $110 for Wr450 radiators, off of Oopsbay. Some smaller pipes to muddle over on the WR rads. rear wheel travel on the St's were also aided by having the R series sloping backward allowing greater travel. Not so sure about that for the K though. Watching with interest anyway.
Oh yes do the chores first and then play with the beastie

It was interesting to me to dig into the K75RT and begin to get a grasp of the similarities and differences between it and the K100.  The K75RT rad has a clip that holds it away from the engine and it is this that keeps the rad hose out of the crank cover.  I think in this sense the 75 is a 100 with the front cylinder lopped off.  The clip on the rad makes it possible to have the 100 fairings work on the 75.  

I do like the GS exhaust but my chances of picking one up for small change here in Canada are meager.  Same for the front end off of a Transalp.  I don't think I have ever seen one of those here in the wild and a quick perusal of the Canadian buy and sell offered up nothing.  I'll keep on the lookout though.

One of the great things about picking up this particular K75 was that it needed some serious loving.  I wouldn't have been able to contemplate the changes I want to do if it was a mostly stock bike and in running condition.  And getting to meet Lorne (the PO) was a huge plus too.

Winter is coming (just like GOT) and I'll soon have more time to spend out in the shop where there is a wood stove, CBC radio - our national radio service - and coffee.    Next steps will be to complete the tank cleaning, replace a sh!t ton of rubber bits and get the bike running again.  As soon as I get it running I will get it not running by tearing it back down to nothing.  Thank you all!

"I think in this sense the 75 is a 100 with the front cylinder lopped off. "




Yep.

(shakes head slowly) 

Oh Chris you surgeon you 

"As for grafting an ABS loom onto your K100, I've never done this.
However, I have done the opposite"


Chris I know you're busy but could I get you to elaborate on this?  I believe I will be swapping the 'free' ABS to the K100 (knowing full well it will cost me dearly) and any insight into the surgery will help.  


I should have picked up a fully functional K75 but where's the fun in that?  

'pologies for the delay.

It was just a simple but time-consuming matter of removing all the loom tape and sheathing, and tracing the origins of the big anaconda that connects to the ABS ECU, and then cutting it free from the main loom. From memory there were connectors for the wheel sensors in there too and these were attached wholly to the anaconda, so they came away with it.

I know it sounds simple to suggest you could 'do the reverse', but I would say it's doable. Only catch might be that some of the brown/ground wires in the main loom might have been upgraded in an OE ABS loom. You could check this with a careful study of the wiring diagram though, and never join a returning brown wire to one with a thinner gauge.

Not a quick job though, but a good one for the brainwaves. PLus, if you use the correct loom tape afterwards you'll have a really spangly loom for your project.

Thanks Chris, no 'pologies necessary at all.  I'll have a go at this later on this winter I think.  I'm still holding out for getting some more riding in before snow and temperatures force me off the road for at least a couple of months (sigh).  I want to be sure that there is no possibility of any riding while I have two bikes torn apart. While wasting time on YouTube the other day I watched a clip of a Ural tearing it up in the snow....hmmmm........

Always fancied a Ural...

...why?

chris846 wrote:Always fancied a Ural...

...why?

Maybe Uralogy is a dormant interest.

It's the original NOS.  The current Chinese version makes it the longest running production motorcycle ever (starting in 1938).  Decent set of snow tires and it is all season!

Chris will relate to these photos taken several cups of coffee into the removal of the ABS wiring from my K75. I did leave the ABS wiring from the relay box to the instrument pod in place.





And yes, it did go again!

As Chris also mentioned about the ground wires, I was surprised to find a few OEM joins buried in the loom where several grounds had been fusion welded together and no insulation wrapped around the join itself.

Good luck - look forward to seeing your progress when the northern summer rolls around.

Cheers

Cool Gaz!  Something like that might be all I get done this winter.    I've noted a few details on your K75 that I will be doing as well such as the solo seat (in stock out in the shop and all the way from Oz) and also changing out the foot pegs.

Have you had any experieince with MotoZ tires (tyres)?  I stumbled across a positive, non-paid for, review of the Tractioneer GPS and they seem very good.  I have no plans for tearing it up off-road but I would like to be able to go places that road tires and too much weight won't allow.

Woodie, I haven't used any of the MotoZ range on any bike. I'm on my third front and sixth rear tyre on the K75 since getting it on the road (over 50,000km). Since I didn't go down the track of changing to wire spoke wheels in non standard sizes (too much of a tight arse to go to the trouble and expense) I am using the standard Y spoke wheels and the challenge in using an adventure type tyre is the front wheel.

The first set were Pirelli Scorpion Trail which have a front 100/90 x 18 bias ply tubeless in their range which is standard size for the bike and I put a 140/80 x 17 on the rear which is a tubeless radial. For my riding which is predominately sealed roads they were very good and the front did 19,500km. I lost the rear to a puncture at 7,600km and had to fit an old stock Michelin T66 replacement as it was all that was available at the town I was stopped at. It had to be replaced after 5,000km due to cracks.

Second front was an Avon Trailrider 110/80 rear mounted in reverse. Bit more aggressive tread than Pirelli but I was very happy with it - did 33,757km so I bought another of them which is currently on the bike.

Third rear was an Avon Distanzia 140/80 R17, again I was happy and it did 12,000km.
Fourth rear was an Avon Trailrider (Distanzia discontinued) 140/80R17 - 14,000km.
Fifth rear another Avon Trailrider 140/80R17 - 13,000km.
Current rear - still sticking to the Trailrider 140/80R17.

I've been very happy with the light adventure type of tyres and in fact fitted a Pirelli Scorpion Trail II 140/80R17 on the rear of my K1100 to go with a Pirelli Angel GT radial front as the last set before I sold it and that was a good combination as well.

Cheers

Having now pondered the Ural thing (pondering seems to be an ever more important task these days) I think it's a comfort reaction to the unnerving levels of technology of this age: a touchstone back to the feeling that the bike depends on me (and probably will, sooner rather than later) rather than the other way round. Y'know, something that can be fixed with a tin opener and a housebrick..

Back to the loom. I posted this on another thread, but anyone tacking a loom might find it useful. The colours/functions refer to a basic K100 1984, but it should still be broadly relevant to most models. I found it helped to identify the wires in a stripped-down-all-over-the-table-what-the-hell-do-I-do-now-? loom.

@Woodie wrote:Thanks Packo, greatly appreciated.  I am currently looking at the space occupied by the battery and toolbox/EFI and thinking that a fuel tank there might be more useful.  I have gone back and forth with the merits of setting it up as a transfer tank or plumbing it with the main tank draining into it.

I did a lot of research into this one mostly because I do a fairly regular 175 miles each way day trip, almost all on motorway. Its very easy to make up a polystyrene mock up for a fabricator.

The simplest solution I had was to relocate the standard fuel pump to an auxiliary tank in this position made in stainless steel and with a removable top access panel to access the pump without a need to remove anything. Routing of pipework was quite simple, outlet from 'new' tank goes at 60psi to the fuel pressure regulator [FPR] as standard, then the fuel pressure regulator to injector rail and FPR return to tank main as they are. Original tank supply spigot is rerouted from FPR as a gravity feed into the 'new' tank. This also deals with venting issues as it all uses the original tank venting.

The top removable panel in the 'new' tank allows easy access to the pump and filter. just let the fuel level drop enough to remove the access panel. You can leave all of the existing wiring in place with a re route of the fuel pump pos and neg wires, either leaving the original warning and level indicators in place or putting new ones in the 'new' tank."


Definitely interested in this possibility Olaf - did you ever end up doing this?

No.....because I found a Randolph tank in US, which incidentally is still there with Ronald Scibetti on FB. It was $750 which was reasonable enough as it takes all the standard K bike pump etc etc inside the tank. problem for me was $250 upwards for shipping cost then add tax 11% and VAT 23% on the lost and then painting at this end.....so it stalled a little.

Then I bought a K1100LT tank for the same money.....but it came with the complete K1100LT attached and is more economical. I just did one of those round trips on it last Monday.

If you box clever under the seat and remove the battery and the other gubbins under the seat just get a block of polystyrene and patiently saw it way until it will fit. You will need to mount it on rubber but that can be done on the battery tray and if you box really clever you could use the original battery clamp screw holes for mounting. You will need to resolve the coolant expansion bottle but as race guys will tell you, it can go anywhere. Having an RS to work with I can tell you its possible to locate it up front inside the fairing. Its not heavy. By making the top of the tank removable you make it easy to avoid removing the tank for routine servicing. A nice side effect is that if you run the fuel down removing the original tank for maintenance is a cinch. 

My calculations suggested you would get 7 litres extra by doing this. However I think the usable extra would be higher as most of us only see about 18 litres max out of the original tanks 21-22 litre capacity.

I had given some thought to increasing the volume of the fuel tank but I would like to move the weight lower on the bike and the additional tank down in the cavity vacated by the battery, etc. would accomplish this nicely I think.  The fuel level sender will be made redundant but I am hoping that an accommodation could be found that will work down in the lower tank.  The fuel level warning light is mostly there to annoy me though as I gauge my fuel level off of my odometer.

Chris thanks for the wiring charts above.  If all goes well I think I will figure out what to remove from the K75 harness and look at adding it as a sub harness to the K100 harness.  Fully expecting the possibility of a few curve balls lobbed my way once I get the harness opened up.

Thanks Gaz, I'm glad that there are so many options with this class of tire.  I am currently running a 'reversed' rear up front on the K100 and would do this again in a heart beat to get a tire that I want.

If you want to lower the fuel weight and have an increase in fuel would it not be reasonable to remove the mapflap box and airfilter and position it where the l/h tank is and use the vacated space for the fuel tank that would sit above the motor filling that space left by the air box. the tank could curve around the frame and be the right hand side of the tank and filler and the left side of the frame and tanks area would be air and mapflap. The air mapflap has to be lighter and allow the bike to feel manoeuvrable without top heavy fuel feel. It would be a big tank then albeit lower down.

Hmmmmm........this is definitely an idea that I will be considering.  I have been pondering a change to the airbox setup (perhaps purchasing the extensively detailed technical drawings that were used for the K75 Madass build).  Adding in extra fuel capacity underneath the tank might be a really good place for it.

Thanks for this K75cster.

One of the up-grades I want to do is to change out the alternator from the OEM 33amp model to the 50amp model.  While looking this up I came across a 60amp alternator for a K1200 (12 31 2 305 888) which, based on the pictures,  looks like it is the same size.  Does anyone know off hand if this will work on the K75?  I'm not taken so much with the increase in amperage so much as I am smitten with the price - 50% less than the 50amp model (see cheap bastid note above).  Heated clothing right about now would be a treat.

Woodie wrote:. . . I came across a 60amp alternator for a K1200 (12 31 2 305 888) which, based on the pictures,  looks like it is the same size.  Does anyone know off hand if this will work on the K75?

Here is one rider's experience.

You can't get any clearer than what that bloke on the link did. I recall setting the K12 60A alternator aside when building Big Block four or so years ago, and using the 50A I had with the K11 'bell housing', but couldn't remember the details of why.

A few years back I was debating adding the 50A alternator to my k100RS.  I seem to recall that the running draw with standard lights to be about 18-20 amps.  The addition of two 50 watt halogen running lights brings it to just shy of 30 amps.  Heated grips adds another 2 amps to the load, maxing the 32A.  That looked pretty marginal which is why I was looking at the 50A.

By going with 10 watt LED running lights, the load is reduced to a bit more than 20 amps which is well within the output of the 32A unit and leaves about 10 amps for heated gear/grips and electronics(GPS, Phone).  That should be enough for heated socks, gloves, and jacket liner for a solo rider. 

IMO, 50A is only necessary if you plan to ride two up with full heated gear and a ghetto thumper on your sound system.

Laitch thanks for the link.  Part of my exploration into this has been a fussy alternator/charging on the K100.  And also a desire to have heated grips and jacket - my tired old achy bones.  I think I definitely fall into the 'Tim Taylor' mentality with some of this stuff.  If 33 amps is sufficient then 50 is better and 60 amps is better still.  No plans for the ghetto thumper but since you brought it up .75....one man's musings on the subject.  The articles on The Blue Groove have been great.