Hi all,

I had been on the search for a motorbike project when i stumbled across a 86 K100 cheap.
The bike had been sitting outside for years and the owner was selling it for parts as it was such a long way from running. A BMW for $300 seemed a steal regardless of condition so home it came with me.
All the body panels (what were left anyway) were pretty much unsalvageable so am planning to do a naked restoration of the bike keeping it all as simple as i can.

While the name 'Kermit' comes to mind that green paint will not be staying!
Intial inspections of the bike showed plenty of grease, oil and dirt along with some butchered electrics. The original contols were missing and a triump set had been crudely attempted to be attached though thinking back on it in not even sure they were attached. The ignition barrel was there but no key only a bored out slot for a flathead , it was a this point i did a quick VIN check to make it wasnt stolen... all good.
The starter motor and a couple of relays were also missing culprits

At $300 you got a bargain.

Many of us here would have given you $300 for the headlight, headlight shroud and radiator shroud alone.  Those parts are made from unobtainium.

It's great to see another one saved, 

Al

Thanks Al, i figured if the motor turned out to be no good it was a cheap parts bike so had nothing to lose.
There doesn't seem to be many at all for sale here in Australia so not surprised parts can be hard to find.

Ordered a starter motor and Haynes manual and got to work sorting out the electrics.
Found it was easiest to label all the connectors as i went tracing them out from the wiring diagram and checking for continuity as i went.
For something that was quite daunting it was actually pretty straightforward thankfully.

The flasher unit and temp sensor looked passed their use by date but given the starter relay missing figured i better buy one of them first.
My goal is to get the engine running first so i can assess how far it is worth going with build.
Keeping with the simple things i gave the MAF a clean up


(Have since connected power and checked voltage at the maf as the vane moves and all checks out 👍)

It was now time to tackle the elephant in the room being the engine and fuel system... i apologise as the following pics may offend but well what can i say it was pretty dire...

Was feeling pretty skeptical at this stage but had heard these engines are pretty bullet proof so decided to take the cylinder head off and see what i could do..

Welcome!  It looks like you have the situation well in hand.  There is a great bike hiding under all that dirt and corrosion.   A bit of patience and determination will certainly find it.

I'll be watching your progress with interest.

good to see another coming back and in good hands

Truly impressive to see you not be put off by all that needs to be cleaned on your K.  It is also great to see that there isn't much that can keep one of these bikes down

Thanks guys, took a few days of soaking and cleaning but the majority of the carbon and grime came off. Its by no means near perfect and im hoping its only mostly cosmetic but i feel as if it would be safe to turn the engine over now.
The actual cyclinders still looked in good shape, can see the original cross hatch on the walls still.
The valve guides felt ok so proceeded to lap the valves to make sure they're sealing as well.

Reassembly of the motor from here was pretty straightforward other than me forgetting to put the valve caps on before the cam shafts..... wont be doing that again! Plenty of oil as i went too.
Timing chain didn't appear to be stretched so back on it went along with the tensioner.
Did notice a small crack in the crank case which ill need to address at some stage though. Hoping a cold weld epoxy from the inside will do the trick? Not sure if anyone has any success with this before or other suggestions?

Cooling system was next to get some attention. Took all the hoses off and cleaned them up with a bit of warm water. Gave the radiator a flush and cleaned out the thermostat/thermostat housing. No leaks anywhere so im calling it a win for this bit. A couple of the fins got straightened out and it all bolted back onto the bike.

Ive left the oil/coolant pump alone so far as im 99% sure its going to need a rebuild. The bottom radiator sludge had a creamy sludge build up where oil has clearly got into it. The oil in the sump seems to be uncontaminated with coolant so hopefully its only leaked ond way.

Finally it was the fuel tank and all its goodies turn. The inside of the tank while dirty doesn't have rust so a good flush is all it needed (several times)



Bit of inox spray and some gentle persuasion and the fuel pump and filter came free. Thankfully the rubber mount and plastic clip is good to reuse, id seen the price of these and was considering which body organ i could do without if it needed replacing.
The filter was stamped 1998 so out with the old and in with the new along with a new fuel pump. Had bench tested thd old one out of the tank by putting power directly on it but it was definitely seized and not coming back.

Pumps can sometimes be resurrected by soaking in white vinegar for a week or two. Once soaked try applying 12v briefly then reverse the polarity. A mate had luck by upping the voltage to 15v briefly and reversing the polarity after soaking.
Regards Martin.

Ive still got the old pump so will definitely be giving that a go Martin. Would be a handy spare if i can free it up.
Cheers

New fuel lines were cut to length and a new (second hand) fuel rail and fuel pressure regulator have been installed. Given the amount of dirt throught the bike i wasnt keen to any chances with contaminating the fuel and blocking the injectors.
The old fuel rail looked like the injectors had been siliconed in so was hoping none had made its way into the injectors.

At this stage of the resto the bike is just about ready to turn over for the first time.
Fresh oil, oil filter and coolant was put in. The starter motor installed and not to be left out the alternator was given a quick clean up.




All new fuses were installed seeing as it was missing all of them and a new battery that a mate had spare was hooked up to it.

Probably worth mentioning that the bike still didn't have any normal controls/switches installed so i wired up a momentary switch to the start wires as temporary solution.

First attempt to start the bike was rather uneventfull. I could here a relay click when when the ignition was turned on but no action when pressing the start button.
Quick check of the wiring diagram and realised the kill switch is 'normally closed' so twisted the kill switch wires together and the clutch switch wires were still loose so twisted them to gether as well.

Second attempt to start the bike and it was now making noise but not the sound of an engine turning over.... all i could hear was the starter motor turning ovef with no load mixed with an occasional grinding noise...... $#/^&@
All signs pointing to a starter clutch, bit of online research and i was convinced it was the starter sprag clutch.

Started stripping thd back of the bike down so i could get to the auxiliary drive and see whats going on with it.

Before I tore apart the intermediate section, I would do a search on "sprag" and try some of the methods to free it up. 

I am watching with interest and hope you shortly will hear that sweet brick music.

I have a K like that in my shed, been there a few years.....starting to get itchy fingers now.

Been a great project so far Olaf and its only early days!

Thanks Point Seven Five, i did have at look some but couldnt get it to work. Was pretty obvious why when i finally got it out!

Rear of the bike stripped i got the old sprag out and found it to be pretty oiled with what looked some damage on the casing.
Doesnt look salvageable but have put it aside for a rainy day just incase. Ordered a second assembly and started the rebuild.

Since the gearbox was now separated i took the time to give it a clean up up and install a new clutch as well. (New clutch bolts and retaining nut of course) Rear housing got a scrub too.
There was some nasty looking oil around these parts that is a bit of a concern but have cleaned it for now and will assess again once i can get it started to warm the oil up and give it a proper flush.

Do yourself a favour and fit a grease nipple to the clutch arm. It keeps out the road crud and water.
regards Martin.

Hman89 wrote: My goal is to get the engine running first so i can assess how far it is worth going with build.

This is a course of action all perspective custom builders should adopt before spending on powdercoating and farkle-buying but it doesn't seem to be a popular one. Thanks for the clear photos and descriptions of your work.

Thanks for the tip Martin!, have just spent a couple of dollars and ordered 1.

Re Laitch gotta admit its hard not go out and do all the cosmetics first! My try a couple a bit of spray paint on the front fender this summer to break it up a bit.

Hman89 wrote: . . . try a couple a bit of spray paint on the front fender this summer to break it up a bit.

Living la vida loca, eh?

The sprag assembly arrived and it looks to be off a late 80's model (its got the 3 oil relief points on the casing). Was fairly straightforward install, followed by the housing and new clutch. Dont have the BMW alignment tool but found the right size socket with a screwdriver did the trick.
Gearbox got bolted on, albeit that would have been easier with a second pair of hands but the small car jack got me through.

Haha Laitch just trying to manage the budget!
Spoiler though i may have bought some new handle bars, switchs and wiring gear.... 🤙

Round 2 for trying to start the ol girl....
The engine is now engaging and turning over with starter motor so sprag change was a success!!
Intial results show spark but no fuel squirting. (Popped the injectors from the engine while still on the fuel rail) Given the state the fuel system was in i cant say i was surprised.
A mate had some spare working injectors of an EF Falcon so have borrowed those so can continue to diagnose the fuel system. They're are a higher cc as the the Falcon was 4.0L 6 cyclinder but am hoping it still show some results.

This is where things got a bit tricky. With the clean injectors installed im still not getting the injectors to squirt. There is pressure at the rail so pointing to an electrical problem.
There is power to the injectors and and am reading the correct resistance when unplugging each injector. Tracing it back it fuel injection control unit, have tested each pin connection and they all seem to be reading correctly.
Given im getting spark im assuming the hall effect sensors and ignition control unit are working correctly. Following this logic i ordered a second hand fuel injection control unit and waited for it to arrive.
Express post is a great thing! Couple of days later back at it. Swapped over the ECU but still no luck...
Bit more research into the ignition system and ive discovered that the ECU will kill the ignition system if it thinks the engine is spinning to quick. Engine speed is picked up by the HES and sent to the ignition control unit first before the fuel ECU so going out on a limb and bit of a loss otherwise it was back online to the wreckers and another igniton control unit ordered.
Plugged in the new unit and success! I now have working injectors!
Electrics isnt the easiest to explain without me rambling on for ages so hopefully the above makes sense.

your on the way

good solve so far

cheers

It's been a few weeks since I've visited this thread.  Judging from your photos it looks like you're making some great progress. 

Couple of observations/questions.  The photo of the oil and the clutch looks like there was water in it.  How was the oil in the engine?  Also, you didn't mention changing the oil seal or the clutch o-ring.  I hope you used the opportunity of the clutch being apart to change them.

It's nice to see an old beast being brought back.  It sounds like you're on the cusp of having it run.

Its clearly been a while since ive posted an update but plenty has been happening!
To put everyone at ease... the ol girl is now running!
Smokey but running none the less!
I managed to get the new fuel pump blocked which threw me for a bit but ran it backwards and came good.
Its going to need some fine tuning (and possibly piston rings) but its enough for me to fully commit to the project now.

It's totally normal for a K bike brought back from the dead to smoke quite a bit at first.

Have you tested the compression yet?

If you can see the crosshatch in the cylinders your rings are probably still good, just stuck from sitting idle.

See if you can find a quart of Marvel Mystery Oil.  The stuff is magic when it comes to freeing up stuck piston rings.  I had a K100RS16V that used a lot of oil (one quart in 600 miles) vs. other K bikes.  Nothing I did worked until I dumped a half quart of MMO in the crankcase, and the other half in a tank of fuel.  I let the stuff sit in the engine during the winter layup, starting and running the engine until it was warmed up once a week.  By the end of the winter the oil consumption was down to less than a quart in 1500 miles.  The guy I sold the bike to reports that oil consumption is even lower now, around 4-5 ounces every 500 miles which sounds about right for a brick engine with 125,000 miles on it.

Well im certainly not the most consistent at providing updates but progress has continued between everything else that happens in life.
Firstly, did check the compression and it wasnt great...arpund 80ish. Am hoping once the rings have freed up this may inprove slightly.

With a running motor i decided to build some motivation and get some easy runs on the board.... strip everything off the engine ready so it nolonger runs...

Cleaning, Bodywork and Paint to follow

Tank fun times:

The blue color is just temporary to prevent rust but still much better than green prior

The tank being a weekends work felt like a warmup for doing what came next with the engine. Teardown was simple but the cleaning seemed to take forever,

Side covers were sanded down to remove as much on the scratches and gouges as possible. Came out ok in the end but may still chase up a better set time and money permitting.