KB's Rusty K100---A Cautionary Tale

[RustyK]

I've always loved tinkering with cars and have been involved in few random builds over the years, but generally left bikes alone. When lockdown hit I has a SM-R that was using a bit of oil, and I stripped it down and rebuilt it. It didnt really solve the issue, but it ran better. When second lockdown hit, I swapped a Superduke engine into it and it was AWESOME. I then bought a 990 Adventure that looked good, but turned out it has some issues (mostly rusty stuff) that I also did a bit of a nut on bolt restore on (motor internals aside). I then bought a ridiculously cheap 1290 SuperDuke GT that was neglected a little and left ouside and you guessed it, had some rusty issues. Why the backstory? Well......

2 odd weeks ago I saw a post on another forum about someone struggling to move on a "Tired K100". I asked for some photos and I initially thought F-no. I then had a few beers in the sun chatting to my wife, and she (or the beer) convinced me nothing is beyond saving. £650, sight unseen.

At this point I saw 2 photos of it - and lets say they were flattering. The first issue was the bike transport company that picked it up - tried to phone me to ask me if I was sure, and if I knew the condition of the bike. I didnt have signal to take that call (probably luckily).

My heart sank a little when it was delivered. It didnt run, it could not have, the brakes were bound, the throttle cable jammed and lose, the tragkorbs all broken, all in all 





I power washed it, put it away and went to the Ardennes on the GT.

This last Sunday I decided to start stripping it down. I must admit I actually gave up several times, and even called a motorcycle scrapper. I'd sit down, have a beer, and then decide lets just do some more.



So much stuff broke or simple crumbled coming off, that I stopped trying to save things. Sorry if anyone wanted anything.


The one thing that did work was the stereo. It provided the soundtrack to the bike's slow destruction. BBC radio 2 - largely because thats what it was on.


How much accessory wiring does an accessory need? Miles of it it seems.


Another wash and I was starting to like it.


I swapped the battery with a new one, and it actually feels like it wants to start. Sometimes it ticks over for a few revolutions and then dies, which I think is an impressive feat in itself.



So, here we go. I'll document the build here, and hopefully ask a few questions and possibly get some suggestions to fixes etc. I have rough ideas where I'm going with it, but its going to be fairly open ended really.

[RustyK]

I've secured 2 pieces of what I need already. A set of K7 GSXR USD forks - I went for forks first as that actually helps decide a few things like color scheme, wheel and brake options etc. I think ultimately I'd like to keep the original wheels (front and back), but run better forks and modern front brakes.

So now I need the triple clamps and yoke, and brake rotor adapters. They are a little pricey so will wait on that for now.


I also have a set of near perfect condition headers - I saw them for £80 online so snatched them up for now.

[RustyK]

But, more importantly my plan is to get it running. I've ordered a full service kit from some outfit in Germany. Plugs, leads, oil, throttle cable, etc. I've even bought a new coil (Ford one mentioned elsewhere in a thread here).

I'll need to take apart and clean the throttle-bodies and see whats what there, and I have a injector rebuild kit (new seals etc) coming although it may be better to go new there. Hopefully with all this she'll start up and run, so I can get her to temp and do a compression test.

[Laitch]

Welcome to the scrum, Rusty!

The Brick's fuel injection control unit, ignition control unit and all its connections thereto are the center of its wellbeing. Get a can of DeoxitD5. D5 is the most effective electronics cleaner that many members here have used. Clean all the Brick's electrical connectors and unit connectors with it before you try starting the engine again. Before starting it, verify its battery is fully charged to prevent fusing together the starter relay contacts. They're negatively effected by low current.

Read the manual at the link in this post. It explains how the Brick's components interact. The information can help with troubleshooting. Because of the engine's dependence on good electrical connections powerwashing is not recommended because water at high pressure can interfere with them.

Good luck with your project. A BMW workshop manual is downloadable from the site. Chilton and Haynes manuals are also useful, as are the videos from Chris Harris. Scroll down through his site's collection; much of it is devoted to Brick maintenance and repair. There are many learning resources in the technical directory here, also.

Good luck with your project. 

[RustyK]

Great, thanks for the details I'll take a look.

I progressed a little with the teardown and investigation. The thottle-bodies are really stiff, and definitely need to be completely rebuilt. I've ordered another pair off ebay too as the springs look a little beyond gone.

First up - I've had an explosion of spiders in the garage - ones I've never seen in my garage before. I think this bike is the Trojan horse. And I think I found where - I had to clean out a massive next under the tank



I also found the one clean spot the bikes has. Inside the electronics compartment.



The coolant overflow bottle is broken, but I'm not sure what to make of this. I poured just under 2 liters of coolant into it to see how much it needed. Seems to have been pretty dry.





I then dropped the coolant. 







The sandy stuff doesnt seen to be that hard, and can squish a bit and come apart, but still. Looking at the waterpump cover I can see some silicon used as a gasket. I wonder if the previous owner was fighting a coolant leak - I'm hoping its just a seal if so.

[Laitch]

Looking at the waterpump cover I can see some silicon used as a gasket. I wonder if the previous owner was fighting a coolant leak - I'm hoping its just a seal if so.

Silicone sealant is the type of pump gasket BMW uses in Bricks. It's used elsewhere, too. It should not be put on so thick it oozes. BMW recommends Three Bond 1207B; many use Permatex RTV.

Excellent photo documentation!

[RustyK]

Yikes. I've got some then - is JB Weld RTV okay?

https://www.amazon.co.uk/dp/B07MP6W193?ref_=pe_27063361_487360311_302_E_DDE_di_1

[Laitch]

If JBWeld's product instructions are followed carefully, it should be suitable.

[RustyK]

Had some more time to work on the bike this weekend.

Almost wish I hadn't. When I pulled the airfilter I noticed some white power like substance on the clean side.



What could that be? Well, never mind the top, what the hell happened in the airbox?





 



I'm not sure how this all got in here other than years and years of standing. The intake pipe is too small for most rodents etc. The picture is being kind to it - it was absolutely full of leaves etc.

Remember the white stuff I mentioned above the filter?







Safe to say this is completely toast. Nothing moved in there if it should, and I dont think contact cleaner will save this. Ordered another on from Ebay quickly

Once you clean things, they do look better.

[RustyK]

I started to doubt the project again. I've read on forums that the rear spline in the driveshaft are known to go if they are not maintained, so I thought I'd have a quick look and make a decision (again).

Removed the ABS stuff - wow that will lighten up the bike


Drained the gear oil


Aaaaaaand.


Cleaned up, I think they actually look good. Please say they look good. 

[RustyK]

And a mate was over that likes restoring metal things - so took the battery plate home with him and sent me this.

I think its looking good!


(Clicky for video)


(Clicky for video)


I was somewhat less successful with the rear bit but its still a massive improvement. A bit more and some paint and I think we're golden

[Past-my-Prime]

Aaaaaaand.


Cleaned up, I think they actually look good. Please say they look good. 

How does the "female" end of the spline on the driveshaft to final drive end look? Mine was pretty bad after 25 years or so of neglect (not the benign kind).

[RustyK]

How does the "female" end of the spline on the driveshaft to final drive end look? Mine was pretty bad after 25 years or so of neglect (not the benign kind).

Um, not great - but I dont know how bad this is. Is this worth prioritising sorting, or could this wait for "one day" if I lube it up nicely?

[The Mighty Gryphon]

Those drive shaft splines are pretty bad but still usable for a while if you are easy on the throttle. 

A good cleaning is always a morale booster.

[frankenduck]

A fair amount wear. Nothing that requires immediate attention. When the hills turn into pointier peaks is when you need to replace.

[RustyK]

I saw and felt that the throttles on the bike we stiff and almost impossible to move. I expected it to be corrosion on the outside on things like the springs. I bought a pair cheaply off ebay, and got to work sprucing them up a little. The moved well, and had some residual dirt on them



But they cleaned up real nice.

[RustyK]

But sadly there are many lessons for me to learn here. I thought I had seen the worst of it, and had resigned myself to replacing pretty much everything on this bike, but when I took off the current throttles I was met with bewilderment. 

Trying to pry off the fuel rail turned out to be a drama. All of the injectors seals would rather unseat themselves than pop out.


The throttles werent just corroded from the outside but completely and utterly gunked up from the inside.




But that was nothing yet. The intake ports and rubbers are an absolute shambles.






How did this happen, and how did it happen in 2 years? Was this drowned in the sea? I've worked on outboard motors and I've never seen anything like this.

[RustyK]

So, I think thats it for this project. I did the math on the bits that I need to buy, and the list is simply miles long. The intake ports are so corroded this now needs a full top end restore. The radiator, alternator, starters etc are all corroded and need to be replaced. The throttle body boots are £35 a pop.

So I went on ebay to see what a running bike would cost. And I saw one for a steal with 12 minutes left on the auction. So I did what any responsible adult would do and I bought it. 

[Past-my-Prime]

And you’ve still got a parts bike to boot!

Looking forward to further adventures. . .