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Jul 12, 2009
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I bought a K100RS off a forum member. It was advertised as needing a replacement gearbox fitted (included) due to the clutch mounting arm mount shearing off. At a round the same time my mate with his K100RS managed to snap the gear lever shaft.....

Here she is after I picked her up. Original colour, 1986. There was nearly a full service history with the bike and included were the original handbook and also a Haynes manual. There were a couple of boxes of spares which when I had a look at I found a Stainless steel fastener kit, filters, replacement filters and some other items.

Ive decided I want to do a full rebild on this bike. I'm going to strip her down into parts, clean/repaint and refurbish. I'd like to have a go at a concours spec bike, but I do tend to upgrade things when I work on them so it may not be a strictly concours bike that I end up with......

The first thing to do was to start removing the fairing panels.

The fuel gauge and temperature gauge were removed.

The screen.

And under the front the surrounds around the front forks were removed.

The front grill panel was removed.

More nuts and bolts were removed.

Wires labelled up as they were disconnected so that I can remember where they go.....

And finally the whole of the front fairing including the headlamp was removed.

The next thing to remove was the speedo/display.

Disconnecting cables and wires and labelling them up.

The bracket that holds the headlamp and front fairing on was next to go.

I started to trace some of the looms back and start to remove them taking pictures of the routing so that I can put them back correctly.

The steering lock was removed by carefully filing away at the brass rivet, inserting the key and turning. Surprisinly it was all freely moving.

More cables disconnected with careful labelling.

The battery was completely fat and did not respond to a charger at all. The bike was last taxed in 2008 - I sytarted the bike before stripping it by connecting the battery from my folding camper and jump starting it. She fired and ran - not smoothly but then the fuel was the fuel in the tank. It was good enough for me to know it she works. In due course the complete fuel system will be cleaned and filters replaced.

I disconnected the airbox - had to remove the air flow meter in order to do this. All the plastic items are being put in a pile ofr cleaning. Whilst the frame is being blasted I shall clean these parts and then store them ready for reassembly.

Some of the routing of wires was awkward. The temperature sensor was disconnected but the loom could not be removed until the frame was lifted (Who designed that?!)

The engine doesnt appear to have many leaks. The sump is covered in oil but it appears the sump has been leaking from the oil filter cover. The quality of the gasket is in question......

The hoses are not in too bad condition - there are one or two which are perished....

I forgot to take the camera into the garage for the next bits. Suddenly I was left with a load of bike parts.....

A frame in need of blasting and painting....

A gearbox with a broken clutch arm bracket. My mates bike that i mentioned at the beginning has the spare gearbox in, his need was greater than mine. I also fancied learning about gearboxes so I have his old gearbox with the snapped gear change shaft. I plan on rebuilding the gearbox with the snapped clutch arm mount into the housing from the gearbox with the snapped gear change lever.

I'm going to get my son involved in this too. (He is nine and wants to help) We have bought him a set of overalls and the first job we can do together is clean all of the plastic parts......

I'm not sure how long this is going to take. Mrs TC has told me it needs to take longer than a month. Last time I bought a motorbike in bits she had expectations of a 6 month rebuild - but I wanted to ride it so had it back together in a month!

I plan to look at a set of K1000 wheels to replace the skinny ones and look at putting some more rubber on. A respray is in order, the paintwork is in ok condition but there are lots of chips in the finish. I saw a Kawasaki in Fowlers this weekend with a lovely pearlescent/metallic green. Other colours thought of is the original dark K100 Blue and the K100 red from the same period.

I'll replace all of the cables as i go rebuild the bike and any other items that look worn.

Hope you enjoy this.

Its been a busy week and not a lot of chance to work on the bike.

I had to MOT my GSA and my wifes Fazer - both passed with no advisories. I had a mate help me with this as my Mrs is definitely a fairweather rider and would not ride it 2 miles down the road to the test centre. Once we got back I asked him for a lift with the engine and we took it, the gearbox, swingarm and final drive outside and de-greased them of all the grime from the oil leaks.

The engine is now sat on one of my benches so that I can strip the head off and check it over. I also want to clean off the casings and get rid of the corrosion thats on them. I want to strip the water pump and check it. The sump is leaking badly so I will take this off, clean it, re-paint it black and then put it back on with new seals. Whilst I have the sump off I'll clean the suction filter.

Whilst we were doing this I set my son to work with all the plastics. I made a solution of TFR up in some cheap B&Q buckets, gave him a pair of overalls, some gloves and a scrubbing brush. The result is that the plastics are a lot cleaner and after some effort with some "T" cut and then some plastic cleaner they will come up well. More on that in future installments....

I started cleaning up some of the parts taken off the bike. I had ordered some Gummi Pflegde after reading Mike P's posts. I set too with the spark plug leads using some Autoglym Vinyl Trim cleaner to clean them and then the Gummi Pflegde on afterwards. It made a lovely job.



I then tried a similar method on the ECU - but using a brass bristled wire brush to get into the nooks and crannies.



I took the frame, battery clamp, wheels, fork bottoms, centre stand handle, centre stand, side stand and bracket to a local company called Mikris to have a price to have them blasted and powder coated gloss black. Ive used them in the past and last time I used them to blast and coat 2 caravan wheels in silver they charged me £15 a wheel. Imagine my shock when they quoted nearly £400 to do the job!

After a bit of digging around I found a company in Nailsworth called QS Enamellers and they have quoted £75 for the frame and other parts and £40 each for the wheels just to coat them as they only have big glass beads in their blaster and they are afraid they will damage my parts.

I think I will be buying a soda blaster to remove the bulk of the paint. From what I can work out a soda blaster does not work well on heavy corrosion but should be ok on light corrosion. I think a mix of this and the wire brush on my angle grinder should do. The other bonus is that I can use the soda blaster to remove the corrosion on the engine, gearbox, swingarm and final drive. Id be interested to hear of anyones experiences with soda blasting.


I saw this at the NEC and it's taken my fancy......

Unless there is very low compression leave the head where it is!

Better to Check the water/oil pump conglomeration AND the auxiliary shaft than worry about the head

If it is a 6 rivet shaft and there is play in the rivets change it now
topcat, if you need any parts it would be worth PMing me. I have tons of new and s/h odds and sods lying around.

Good luck with project, will be watching with interest :thumb2
Unless there is very low compression leave the head where it is!

Better to Check the water/oil pump conglomeration AND the auxiliary shaft than worry about the head

If it is a 6 rivet shaft and there is play in the rivets change it now

I want to do the valve stem oil seals as they are leaking a bit.

Inlet and exhaust ports covered. That was done after I took the 'photo.
Now I've kind of settled into my new job and after a recent bout of wet weather all the jobs I had waiting to be done.

My mate kicked my arse on this - there's a local show in April I want to enter this for so I need to get moving.

I've got a big pile of parts wrapped in bubble wrap from the powder coaters. All I need now is an engine/gearbox/swing arm/final drive assembly to bolt it too.

I'd bought a soda blaster but it wasn't really doing the job I wanted. I'm not sure how the castings are treated - wether it's raw Ali or wether it's anodised but it wasn't shifting the corrosion I had.

I'd tried an aluminium detailing spray which was acid based - this etched the surface but didn't really get rid of all of the black marks. I'd tried PEEK polish with a mop in the Dremel. I still wasn't happy. I tried brass wire brushes in the drill and still not right - too shiny and not even enough.

In a flash of desperation I noticed a spray can, a wondrous vessel full of a miracle liquid. No less than the 40th formulation of that liquid. I grabbed it. Saw a piece of wire wool lying about. I sprayed, I rubbed. I got a rag, gave it a wipe - then the miracle occurred. All Hail WD40 the God of polishing BMW casings!!

The finished article - very happy with this. Next job the gearbox!

Had a week away travelling and staying in hotels so nothing done during the week. On Saturday the weather was too nice to be working on a bike so rode one instead. As part of the trip I called into Cotswold Motoradd and met with Nick, taking his recent kind offer and letting him have the parts list I have to quote. Good hot chocolate too.

I spent today working on the K.

The gearbox was next to get the wd40 and wire wool treatment.

You can see how effective the wd40 and wire wool is - I've done a test patch in the bottom right corner.

A bit of perseverance gave these result.

Next to get the same treatment was the engine. I've previously drained all the oil from the engine so I was able to turn it upside down and get into all the awkward bits.



I then decided to rub down and paint the sump. Is also removed a few brackets and the injector rail. I rubbed them down and used some satin finish hammerite black. I had a fan heater and a halogen heater running to try and get some heat in the parts and heated the tin of paint on the stove before spraying...

I'm hoping that next weekend I can get the frame onto the engine - if I have time during the week I'll start building up some sub assemblies (side stand/main stand for a start and maybe the forks if the seals arrive).
Good job - keep going! I love rebuild / project threads...
It's been a busy few weeks. Had a friend come over and help out with some of the heavy lifting in between helping a friend of his move house....

Before we installed the engine to the gearbox and seeing as it was upside down I thought it was an opportune moment to install the oil filter.

Old one out.

New one in - it's very tight in there.

And bolted all back together.

I didn't get any pictures of the process - but put thee nine on its nose and bolted on the gearbox. Then bolted on the swingarm and then bolted on the final drive. Then bolted on the frame and suddenly it looked like this.

While putting on the clutch arm I decided to modify it and drilled and tapped it to accept an M6 grease nipple so I can keep pumping it full of grease.

I built up and fitted the handle...

Installed the cleaned fuel injectors and painted fuel rail.

That was last weekends work.
Today I got chance to work on the bike again. Yesterday was spent moving plant pots (with plants in) - around 100 in all...

We started on the front end building up the headstock.

The fork legs were built up with new seals and filled with new oil.

We then added the handlebars and the clocks.

Doesn't seem like we have done much - but a lot of time was spent removing powder coat from where it should not have been.

I was meticulous in marking where I wanted masked by the Coaters but it seems they were not as meticulous in masking up. Should have done it myself!

I'm away all week this week so won't get much more done but next week I'm hoping to get the wheels and tyres on and wiring loom installed and start to build up the switchgear, lights and gauges.

I can see this coming together quite well now.
Thanks for taking the time and trouble to post, I really enjoy following these builds.
Nice post, and it's great to see a practical rebuild where the end result, engine, still has a patina that shows a little of its age. I'm not being rude about the finish, it's what I would do if I had the same problem.
Missed writing up what we did last weekend.

Took the powder coat off the handlebar ends - it was too think for the grips to go over. Threaded the heated grips wiring through the holes and fitted the grip assemblies.

Added the two ecu's and started routing the wiring round the bike.

A right middle of wires although someone labelled all of the wires with what they do before they took the bike apart...

Added the wiring to the clocks.

Added the cooling system plumbing.

And the rest round the other side...

I also uprated the wiring to and from the starter relay. These K's have a reputation for starter difficulties and on many of the K forums it's recommended to use thicker gauge wiring - so with everything apart it seemed sensible to do this.

I will also uprate the wiring to the headlights and use two relays to fire them directly from the battery which will hopefully give off a bit more light.

I purchased a new battery and tried to start her. I'd rebuilt the tank with new hose and a new filter. Fresh fuel in the tank, new spark plugs and water in the cooling system. Nothing. It turned over but didn't fire.

Checked I had sparks. All present and correct but the spark plugs were dry. I could hear the fuel pump so whipped the injectors out and no fuel.

If cleaned off the earth point in the centre of the frame - so checked this. Then had the realisation that nothing connects the frame to the battery and with all the lovely new powder coat the frame was not earthing through the engine as it should. Frame tilted and the bell housing earth point cleaned off.

I now had a spark and fuel and still she would not start. So I started swapping ecu's with a friends known working parts. Purchased a new s/h Hall effect sensor and swapped that. Swapped the air flow meter. Still the bike wouldn't start and still getting sparks and fuel......

Last thing to swap was the coils - and she fired into life....

Nice post, and it's great to see a practical rebuild where the end result, engine, still has a patina that shows a little of its age. I'm not being rude about the finish, it's what I would do if I had the same problem.

Thanks - a lot of it is about being realistic about the bike. She is not perfect and will be ridden. If I'd have wanted a concours bike I wouldn't have bought this one as a base.


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