I bought on September a former Swedish police 1992 K75 RT for a project base. It's technically quite good condition, but with 128 kkm's in odo, requires some thoroughgoing service.
A short clip of picking up the bike.
Preparing wheels for powder coating, fork service etc.
Last edited by -mek- on Fri Apr 24, 2020 6:16 am; edited 1 time in total
Steering head bearing was good. So just cleaning with kerosine and new CRC Super Longterm MoS2 Grease. I also drained the fork oil and flushed the forks with kerosene. I changed the springs to Progressive suspension. First I filled up with 420 ml Motul 7,5 W fork oil. Then adjusted the oil level to -160 mm (fork compressed, without springs), also removed about 10 ml oil. I think about 410 ml will give the -160 mm oil level, if you don't have a tool for measuring oil level. PS springs with the spacers that came with them, gave about 30 mm preload. Oil level and viscosity is easy to change later if I'm not happy, we'll see on May.
My bike has black forks, engine and final drive. I'm still not sure, whether to repaint valve and camshaft covers, since the fairing seals have scraped the paint away a little bit.
My RT had OEM heated grips, working. They were easy to uninstal since also the left heater element was glued to the sleeve which was then fastened by two M4 screws to handlebar. I started replacing the RT handlebar with LSL Flat Track handlebar, which I shortened to 800 mm. 10 mm hole on the middle, underside for heated grip wires and two 3,3 mm holes for fastening the left grip sleeve, then M4 threads. No problems.
The most work was sanding the right end to 22 mm. Almost all bars that are sold as 22 mm bars aren't really 22 mm, but 7/8" which is 22,2 mm. So the throttle grip does not rotate free on that, but the bar end must be sanded to 22 mm. Lots of sweat with sandpaper... I also covered the sanded end with thin layer of paint for protecting against rust.
Most of the service, ignored by previous owners, is done. I'm afraid the drive shaft splines have not been lubed for a long time. They were a bit worn, but hopefully will do still some years. I'm not gonna put so many km's for this bike. Two exhaust valves must be adjusted, but I'm still waiting for the ordered shims. I'll change the brake lines to Probrake Stahflex, but won't do it yet since the front line change requires cooler removal and I've still not got the Samco silicone hose kit yet.
When I get the wheels from powder coating, I'll build the front fender fastening. I also need the wheels for seeing how the bike stands with the new fork springs and Wilbers shock, if I have to adjust the front preload. Just then I'll be able to build the seat fastening to the right position and fit the Leo Vince GP-Style universal muffler to right position.
__________________________________________________ 1983 K100 naked upgraded to K100LT spec after spending time as an RS and an RT 1987 K100RT Others... 1978 Moto Guzzi 850-T3, 1979 Moto Guzzi 850-T3 California,1993 Moto Guzzi 1100ie California 2020 Royal Enfield Bullet 500
__________________________________________________ 1983 K100 naked upgraded to K100LT spec after spending time as an RS and an RT 1987 K100RT Others... 1978 Moto Guzzi 850-T3, 1979 Moto Guzzi 850-T3 California,1993 Moto Guzzi 1100ie California 2020 Royal Enfield Bullet 500
Finishing the service. Two exhaust valves must be adjusted. Also got the brake lines changed to steel braided ones. The hose from front master cylinder to ABS is very tightly fitted under the frame, behind radiator. Removed the radiator first, but just when I got also the ECU loosened I got enough space for changing the hose.
__________________________________________________ 1983 K100 naked upgraded to K100LT spec after spending time as an RS and an RT 1987 K100RT Others... 1978 Moto Guzzi 850-T3, 1979 Moto Guzzi 850-T3 California,1993 Moto Guzzi 1100ie California 2020 Royal Enfield Bullet 500
I wasn't so happy with the U-shape tube seat mount that I got before christmas. In my mind the seat sat a bit too high from the frame and I found it difficult for fastening hinges and original seat lock. So I let the grinder and drill sing... after few hours I got another solution. It still requires some fine adjusting, but I think it fits better than U-mount.
I got the elecrics ready and tested everything that can be tested without starting the engine. Replacing the dashboard was easy with Marulabs BEP 3.0. I also succeded pushing the dash connector trough the frame. The ECU-box must be removed first and it was still very tight between steering lock and frame tubes.
Right side coolant hoses from Samco didn't fit. I got the wrong set of hoses, now waiting for replacement. I first tried to make side-/center stand bracket and use the original ruber pad, but didn't succeeded with the tight and close bends, so I made a new one. Maybe it needs some rubber on it also. Welding 1,5 mm stainless steel exhaust with an inverter and 2,0 mm rutile coated electrodes was surprisingly easy, even the result is not so pretty... just be carefull not to burn trough.
Some notes... I built the bike for my self, for everyday commuting. Not for someone elso or for the show. So, I haven't listened so much for the comments and (good) advice I've got. And I know my built isn't a pure street tracker... My idea was to build a bike it would have been if BMW had built a street tracker in late 80's. So that's why I didn't use any led blinkers or lights or mini bar end mirrors. All the lights and blinkers, as well as the muffler are CE approwed. However, the muffler approval is not for this specific model and it's quite loud, even with the db-killer on. For the first two rides I feel I succeeded. The riding position is nice, the bike handels well. Suspensions is quite sporty, but that's how I like it.
I still have some minor finishing to do, but a test ride was needed for example to know if I must adjust the BEP 3.0 switches before I seal it under the gas tank.
List of modifications: Cut rear frame, pillion grip from Krad Werk Cut rear fender Self made rear fender & blinkers mount Lucas style backlight Ermax plate holder Foundry MC custom made saddle Self made saddle mounting plate Gas tank repainted to BMW Indianapolis rot metallic with black stripes by Jani Stenius Front fender from Krad Werk, painted to glossy black Self made front fender mount Self made front brake line brackets Stainless steel brake lines by ProBrake Progressive suspension front springs Wilbers 630 series rear shock BMW K 75 S mirrors LSL Flat Track handlebar Ariete grips for BMW R 1200 GS Radiator closer to frame, like K75 S and K75 C Samco silicone coolant hoses from Racebikebitz Leo Vince GP Style muffler Self made muffler and side/center stand brackets Front light 7" and holders from Krad Werk Acewell CA085 dash Marulabs BEP 3.0 dasboard adapter Self made dash mount Foliatec led warning lights Powder coated wheels by Laaksojen laatupinta Oy Engine protectors from BSK Speedworks Dart Classic flyscreen Self made radiator protector CNC gas tank emblems BMW OEM tankpads Merit horn Ariete fork boots from Wunderlich
It's good to see it finished - well done that man!!
__________________________________________________ 1983 K100 naked upgraded to K100LT spec after spending time as an RS and an RT 1987 K100RT Others... 1978 Moto Guzzi 850-T3, 1979 Moto Guzzi 850-T3 California,1993 Moto Guzzi 1100ie California 2020 Royal Enfield Bullet 500
That's an excellent project, you've got a tidy looking bike that'll beat any new bike when it comes to forever reliability, cost and ownership and spares parts, and simplicity and ease of maintenance. Plus, you're the guy who knows it from end to end because you built it.
- and you can alter it or improve it anytime you want!
I'm biased, but I think the K75 is a much better base for a build. The K100 is much bulkier and heavier by comparison, too much so for the extra 'power' (ahem) that it puts out, if not the comparative coarseness over the '75. The '75 just makes a much more usable bike for nipping around on. Just my opinion.
Hope you enjoy it as much as I enjoy mine!
__________________________________________________ Sometimes I'm not really Suzi Quatro.
__________________________________________________ 1983 K100 naked upgraded to K100LT spec after spending time as an RS and an RT 1987 K100RT Others... 1978 Moto Guzzi 850-T3, 1979 Moto Guzzi 850-T3 California,1993 Moto Guzzi 1100ie California 2020 Royal Enfield Bullet 500
chris846 wrote:I'm biased, but I think the K75 is a much better base for a build. The K100 is much bulkier and heavier by comparison, too much so for the extra 'power' (ahem) that it puts out, if not the comparative coarseness over the '75. The '75 just makes a much more usable bike for nipping around on. Just my opinion.
Great result well done. I wish I’d seen that trick with the rad hose before I did mine .
__________________________________________________ 1985 BMW K100RT + Hedingham HUB and LL’s. VIN 0028106. 1986 K100RS in boxes. VIN 0141918. 1954 Royal Enfield 350 Bullet. Original. 2000 Hayabusa with Charnwood chair, Wasp forks and EZS wheels.
__________________________________________________ 1983 K100 naked upgraded to K100LT spec after spending time as an RS and an RT 1987 K100RT Others... 1978 Moto Guzzi 850-T3, 1979 Moto Guzzi 850-T3 California,1993 Moto Guzzi 1100ie California 2020 Royal Enfield Bullet 500
Water pump seal was leaking coolant, so the seals and ruined shaft must be replaced.
Also changed fork bushings.
My K75 also got a facelift with BMW R Nine T Urban GS fairing. Welding the headlight/meter/fairing mount was lots of measuring, bending, welding and grinding. I also replaced the OEM fork brace by self made version. Fork boots didn't really fit so good with the OEM brace. Both were powder coated. Since the style not really is pure street tracker, let it now be K75 ST, by the R80 ST, the sister model of R80 G/S.
I test started the bike on February after the water pump replacement and all worked fine. Three weeks ago I got my brand new GS and swapped the K75 to car shelter and the new R1250 GS into the garage for adding some equipment. I renewed the battery to K75 a year ago and it has been on CTEK charger the whole winter, so I was really surprised, when the starter could not crank the engine. I then took a jump start from my wifes car and it started fine.
When testing more, sometimes the starter could crank the engine, but mostly not. So I disassembled it and found the other brush quite worn and the starter full of coal dirt. I ordered a full repair kit from tills.de. Let's see if cleaning the starter and replacing brushes and bearings helps. If not, my next suspect is the Hall effect sensor. It may be repairable as well, at least the wires.
Last edited by -mek- on Fri Apr 24, 2020 6:06 am; edited 1 time in total
-mek-: do NOT polish the copper segments on the armature. The carbon marks you can see on there are filling microscopic pits in the copper. It gives the brushes a smoother ride and a greater contact area. By all means, gently scrape out the dirt between the copper segments.
__________________________________________________ 1983 K100 naked upgraded to K100LT spec after spending time as an RS and an RT 1987 K100RT Others... 1978 Moto Guzzi 850-T3, 1979 Moto Guzzi 850-T3 California,1993 Moto Guzzi 1100ie California 2020 Royal Enfield Bullet 500
Dai wrote:-mek-: do NOT polish the copper segments on the armature. The carbon marks you can see on there are filling microscopic pits in the copper. It gives the brushes a smoother ride and a greater contact area. By all means, gently scrape out the dirt between the copper segments.
I overhauled the starter and cleaned all ground and power connectors, won't start. Yesterday I got help from my wife and was able to check the voltage also when starting. Battery had 12,6 V, but when starting, it dropped under 7 V. Somehow my Ctek XS 3600 charger seems to destroy batteries during winter (battery was one year old Exide AGM battery, 19 Ah). It sure isn't any plug in and forget -charger. I got new battery yesterday evening, just before the local part shop's closing time. With new battery it works brilliant again.
Thinking positive, the starter should have been overhauled anyway quite soon and specially the ground connectors are quite common reasons for starting problems also, so it's good all are checked and clean now.
Bad thing is that we still got 5 cm new snow last night, next few days it will still be just around zero, so not yet riding.
Great job on the K75 - I'm another big fan of a slimmed down version of this model.
You will find the R80G/S seat much better. I have both the dual seat and the single seat for my R80G/S and I find the single seat more comfortable than the dual version. In fact I used that single seat for a short time on my K75 as I was still working my way through the style that I wanted.
K75 "ST" by -mek- Tue Nov 06, 2018 2:37 am
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