Restoring an '85 K100 to...something.

[iiXioM]

Hello all.

I've posted here long ago with help on this same bike. It was a friend's and has since been out of my hands and he let it go downhill. I've essentially inherited it off him and would like to begin restoring it. I would like to go through it and bring everything back to factory-level functionality. I'm unsure what model k100 it is. I do have the saddlebags for it, hopefully that denotes what submodel it is.

Here's the breakdown:

125,000 mi on the odo. Gears broken, no idea actual mileage...
Nearly no fairings
No blinkers. The ones on it were put on by my friend, wires never run.
Tail light doesn't work off the brake levers (previous owner put in some sort of bypass with a spring and piece of string)
It was turned into what it looks like now (no fairings) by the owner previously before my friend got it. I'm not too much of a fan of the cafe racer look.
Needs new tank
New Tires
It has an ignition bypass on the side of the bike that cranks the starter without the key in. won't start without key set to 'on'.
New seat. Badly. (will replace with at a minimum, a corbin)
..mirrors...

So I need advice, where do i begin? I already plan on the usuals, drain -all- fluids, replacing tires. From where, where would i go? Should i start on wiring real blinkers? Should i tear the whole thing down? Should I just get the splines out of the way first? The bike did work before it sat up for a few year, so i know the motor isn't seized. Is there somewhere I can find exploded views of...everything? lol.

[Chaos]

wow, Kudos for attempting to revive it.  I'd drain the tank and clean it first.  Then go to The workshop/no start here and figure out the starting issues.  Hopefully the wiring not too whacked out.  Check the splines, if they're bad it may not be worth bringing it back. 

[iiXioM]

Are splines expensive to replace? I'm no stranger to taking this thing apart so I'm not worried about the labor involved in getting in there.

The wiring is completely cracked out. The previous owner before my buddy hacked it to hell and back. The buttons on the dash are stuck, there's black electrical tape over a the constantly-on hazard light, etc. All sorts of things here and there.

[Chaos]

Splines can run $400 to $1000, maybe less if you can find some used ones.  85 K100's had different splines than later ones, along with wiring harness and other sundry pieces.  On the bright side, looks like the bike is protected by a guardian bell :yes

[iiXioM]

That does sound pricey. Can I still buy "new" splines from BMW or are they no longer manufactured? I'm hoping the splines are ok on this one. Highly doubt it, though. The wiring harness is what's going to drive me batty to get everything working correctly.

And yeah...i gave my buddy that bell. somehow it made it back to me. So I gave myself a guardian bell. lol..

[Laitch]

If you haven't got a manual yet, you can download one from the Motobrick Technical Library It covers your bike's model and year, among others. Exploded diagrams are at MAXBMW.

[Martin]

Clean it and then try and do an assessment of what needs to be done. Then try to price the parts needed, and when you have a figure, double it or possibly triple it. A gutsy effort, start a post and keep us updated. Congratulation for even considering a rebuild.
Regards Martin. :2thumbup:

[iiXioM]

Well, I ordered a PC680 to replace the crapped out battery that's currently in it. I tried to pop open the gas cap to assess the inside (water leak, gunk, etc) aaanndd...snapped the key in the lock. Luckily it was a dupe and not the original key with the hinge. Got 2 keys made today at a local locksmith. Sprayed the lock hole with liquid wrench, hopefully it'll help me unlatch it.

Talked with my buddy the other day and he reminded me we lubed (heh heh..giggity) up the final drive splines with honda moly a few years back. he hadn't put too many miles on it since (less than 5k) and the splines werent chewed up. I'm hoping the other splines are good to go. I plan on regreasing the final drive as well.

In everyone's opinion...Does this bike look like it can be salvaged, or even worth it? Aesthetically speaking, i know it looks like a neglected step child, but it worked prior to sitting up.

So far this is what I'd like to do:

Get bike to at least start (priorities, right)
clean/degrease all the things
drain and replace all fluids
Replace all hoses
redo wiring
tires
lube (giggity)
replace all brake pads (front ones were replaced by me ~3 yrs ago, better safe than sorry)
fix instrument panel (plastic gears in it are basically gummies)

I believe from here it'd be a matter of fairings and other nonessentials, right?

[johnny]

greetings...

id put the iconic 22 liter on the bung and ride it... postpone the nonessentials after you know you can getts some yeeehaaaa...

j o

[TimTyler]

I'd either  part it out or put it on Craigslist for $400.

That bike looks like it will create unending headaches for you.

[iiXioM]

I'd either  part it out or put it on Craigslist for $400.

That bike looks like it will create unending headaches for you.

What makes you say that? It was working (mostly) fine before it was left sitting up.

greetings...

id put the iconic 22 liter on the bung and ride it... postpone the nonessentials after you know you can getts some yeeehaaaa...

j o

I've still got the side bags and the top trunk. They'll definitely get thrown back on there.

[Elipten]

Try and get it running and assess what it will take to then make it reliable .  Seat is no big deal.

[Vespa no more]

It's so (visually) far gone that the muttering has started

But treat that as a strength - don't worry about cleaning it up other than to get the parts working ... a rag and kerosene keeps the patina.

These bikes are well engineered so it might respond with some TLC ... and money

Some parts are expensive. But if someone is breaking up a bike you might get items cheap. A good second hand spline for an 84 K100 cost me $50, final drive $70... Also put the call out for parts. Everybody here is hoarding.

Consider it a puzzle / challenge. Enjoy the journey.

Some quality time ahead - good music in the background, cold beer to hand, the smell of mechanics and little victories. And if it goes to shit use the parts on another bike.

Re: tank. See my post... soak the innards in white vinegar and wipe. Repeat repeat.

Better than pouring coins through the slappers (pokies) or throwing it away on lotteries.

Keep the updates coming.

[TrueAce]

Noble goal to 're-build, but the down-side is that could be very expensive with undetermined miles in excess of 125,000. I agree with TimTyler that the time and expense will be excessive.............fuel pump, brake master cylinders, brake calipers, possibly brake discs, shock, relays, clutch, forks rebuild, electrics.......You know.......all before any cosmetics. Maybe a running lower mileage would be a less challenging project......just sayin' a LOT of work. This bike is representative of a " new life bike", aka cafe or scrambler, rather than restoration.

[iiXioM]

It's so (visually) far gone that the muttering has started

But treat that as a strength - don't worry about cleaning it up other than to get the parts working ... a rag and kerosene keeps the patina.

These bikes are well engineered so it might respond with some TLC ... and money

Some parts are expensive. But if someone is breaking up a bike you might get items cheap. A good second hand spline for an 84 K100 cost me $50, final drive $70... Also put the call out for parts. Everybody here is hoarding.

Consider it a puzzle / challenge. Enjoy the journey.

Some quality time ahead - good music in the background, cold beer to hand, the smell of mechanics and little victories. And if it goes to shit use the parts on another bike.

Re: tank. See my post... soak the innards in white vinegar and wipe. Repeat repeat.

Better than pouring coins through the slappers (pokies) or throwing it away on lotteries.

Keep the updates coming.

Yeah, that's exactly it really. I'm looking forward to wrenching on it every few days with some tunes in the background. I'm in no rush to take it outside for a hundred miles tomorrow or anything. I'll use it as therapy until im able to actually get it safely on the road again.

Noble goal to 're-build, but the down-side is that could be very expensive with undetermined miles in excess of 125,000. I agree with TimTyler that the time and expense will be excessive.............fuel pump, brake master cylinders, brake calipers, possibly brake discs, shock, relays, clutch, forks rebuild, electrics.......You know.......all before any cosmetics. Maybe a running lower mileage would be a less challenging project......just sayin' a LOT of work. This bike is representative of a " new life bike", aka cafe or scrambler, rather than restoration.

I definitely know it's going to be a lot of work, but im actually looking forward to it. The money thing...i know it can get pricey but I'm hoping fleabay and the forums could help with some of that.


So last night I got home and tried the new keys I had cut. Neither of them work. In the tank (wont slide all the way in) nor in the ignition (just wont rotate). I still have the original hinge key but im worried about breaking it if i put too much twisting torque on it. Which way is the key supposed to rotate to pop the top? Counter-clockwise, right? How hard is it to get new sets of locks?

Also, looks like the PC680 I ordered from autplicity is back ordered. I found some on Amazon but with 170CCA as opposed to the 220. Will the 170 work?

Thanks for all the advice guys!

[iiXioM]

Small interesting update:

I managed to finally pop the gas cap open. It was super sludged out. hit it with copious amounts of WD-40 and cleared all the nasty gunk. I'm able to get into the tank with no issues. The inside of the tank is clean but the gas is definitely useless. No rust or dirt inside at all.

I had a lawnmower battery sitting around so I wired them up to see if I can get power to the electrical system and if it cranks over. I turned the key (which i also had trouble getting to switching to "ignition" position). I got power! Decided to see if it would crank over, and the bike churned out a few spins. The battery was crap but at least I know it's not seized, starter works, and it puffed out some smoke. It's definitely going to live again very soon. Now if I can find a damn battery somewhere...

[Vespa no more]

Change the oil. No point trying to run it with bad oil.
You should go through the basics and clean them first - drain bad fuel, oil, coolant. Injectors might be reluctant to come out. Maybe new 95 or 98 octane might let you dodge this ... forcing the injectors out might dislodge the pintle cap and damage lower o-ring... then it's service time at approx $30 each.

What is the brake master cylinder like? Mine was seized and ... bought a new one. Should have reused the old one until the bike was ready to return to the road. $193 for the piston and rubbers only(complete unit). Welcome to BMW pricing (admittedly some things are acceptably cheap). Hope a brake fluid flush will work. If brake lines are blocked, they might clear with some tie wire pushed up the line. My front master cylinder to steering head was beyond reuse but the others cleared easily.

See my post on cleaning the fuel tank ... vinegar wipe repeat rinse

we will be interested to see if your creature from the black lagoon gets back on the road.

Regards

Guy

[iiXioM]

Change the oil. No point trying to run it with bad oil.
You should go through the basics and clean them first - drain bad fuel, oil, coolant. Injectors might be reluctant to come out. Maybe new 95 or 98 octane might let you dodge this ... forcing the injectors out might dislodge the pintle cap and damage lower o-ring... then it's service time at approx $30 each.

What is the brake master cylinder like? Mine was seized and ... bought a new one. Should have reused the old one until the bike was ready to return to the road. $193 for the piston and rubbers only(complete unit). Welcome to BMW pricing (admittedly some things are acceptably cheap). Hope a brake fluid flush will work. If brake lines are blocked, they might clear with some tie wire pushed up the line. My front master cylinder to steering head was beyond reuse but the others cleared easily.

See my post on cleaning the fuel tank ... vinegar wipe repeat rinse

we will be interested to see if your creature from the black lagoon gets back on the road.

Regards

Guy

I'm sure the injectors need to be cleaned up and tuned. 

The brakes are definitely not seized. They definitely do need to be flushed though. I doubt they've ever been since my buddy got it.

Creature from the black lagoon...I'm going to have to stamp that on the bike somewhere. Or call it Gillman once it hits the pavement!

[iiXioM]

'Nother nice update:

Had a few min and decided to tinker. I popped off the gas cap and proceeded to empty out the tank. The gas in it was very watered down since the gasket was essentially useless on the cap. Surprisingly, the inside of the tank was very clean. A few rust spots here and there but very similar to Vespa no more's second image in his fuel tank cleaning here: http://www.motobrick.com/index.php/topic,8283.msg62911.html#msg62911

I did buy a bunch of vinegar (Gotta love sales) which I'll use for rusted screws/cleaning other rusted parts. Do ya'll recommend I run vinegar through the tank anyways? If so, should I pull the fuel pump out? The actual fuel line inside the tank looks great, but I will replace it anyways.

Also, great news! I got this thing to turn on! Testament of BMW reliability. After I drained the tank, dried it, I threw in some fresh 93 octane gas, played with the starter and choke, and started it. As you can see here, it was sort of happy to start:



So i've noticed two things:

The starter does the spinning thing. I remember seeing something about a fix for this somewhere, so I know that's repairable.

The somewhat pinging sound that can be heard, would this be associated to the the gearbox like this?



Thanks for all your help guys. This forum definitely helps a lot!

[Martin]

Did you yell IT"S ALIVE if so you can call it Frankenstein well done.

[iiXioM]

Did you yell IT"S ALIVE if so you can call it Frankenstein well done.

I yelled it out, and then proceeded to cackle like I had a frontal lobotomy. Or a bottle in front of me. I can't remember which. Muahahahaha! It was definitely exciting. I plan on tearing it down soon, hopefully the inside inside isn't too bad. This'll be the first motor I ever really crack into. Should be fun.

[Elipten]

Congrats

[Laitch]

I plan on tearing it down soon, hopefully the inside inside isn't too bad.

Why are you tearing it down—low compression values or what?

[orforester]

I am with Tim Tyler. Part it out.  I had a 85 that I worked over, but it was running, good, no smoke, gas tank good.  Spent $2K getting it back to good shape, not pristine by any means, just reliable.  You will spend a lot of money on that thing and you can buy them in PNW for $100-$2500 in great running shape.  Cut your loses. Just my Opinion.

[Vespa no more]

Looks like it came out of a swamp. And on this basis be careful what you clean - if you want to keep THAT look.

I hope you changed the oil. False economy not to.

The pinging maybe the antibacklash spring but let the bike get to operating temp first. It is not a small job. Turning the silver idle screw (yeah the one with blue loctite on it) to increase revs to approx 1000 or 1100 may lessen the noise (record how many turns you did for later). I saw someone with a microphone go round the motor and measure the noisiest section (ie output shaft behind alternator) which is best method I have seen.

The whine is normal.

Best to flush the tank. Once dry, I vacuumed mine to remove grit. replace fuel filter - doesn't need to be BMW brand. Check this forum for alternative BMW parts.

Clean and gap plugs (0.6 - 0.7mm), check the fuel lines for cracks and replace (inside tank needs submersible hose not standard fuel hose). The fuel in under pressure - don't want any leaks and fires. Check and clean air filter (mark the outside edge and top before removing. Easily put back in wrong).

Allow to get to operating temp and check that fan comes on. The bearing in these is a bush I believe and can go bad. Haven't had mine out.

injectors are probably dirty but check you can check the spray from each by removing the FI rack and keep injectors in place. This is not accurate. Also check on youtube for others' suggestions. Caution: injectors may be hard to get out. Clean the area around them. Crud will build up around body and may significantly hinder removal. Some spray might help (WD 40 et.al) but don't then let it fall into cylinders. Use a air compressor to clear beforehand. Vice grips (or similar) can be used to grab the metal body (quite robust) as I had to on number 1 injector. O-ring and pintle cap may be damaged and require servicing ... see post on 4 hole pintle on this forum.

Anyway your bike seems to be firing on all cylinders ... maybe leave well enough along for the next week. Just change that oil. And don't rev the shit out of it (up and down up and down) when cold - build the revs gradually and give it a chance to settle and come up to temp. Once the fan comes on then rev it if you must. As we all know motors don't mind being used - just not abused. And this is the huge appeal of K bikes - that quality motor. Look after it.

A manometer is a useful item for balancing throttles - assuming all else is fine... unlikely because rubber hardens as it ages (dehydration??) and air-tight seal is accordingly compromised.

You might have fluked a bike that under the dried green slime / residue might be quite roadworthy (something we are all unlikely to agree on - 'cept that it needs to be safe)

Keep the pics coming

Regards

Guy