Hallo! 

Hello everyone. Figured id introduce myself here.

New owner of a 1985 (vin says 1984? #F0050486) K100RT (47,287 Mileage) Found this on craigslist at a motorcycle-dismantler. 

Was looking for a project for the Winter-Spring, and I didnt find that the Kawasaki/Honda/Triumph look to be what I was looking for. So I went with a Beemer. 

Funny actually, my uncle runs a BMW repair shop in California. So maybe its a family thing. 


Anyway this "Flying-brick" I found on craigslist. They wanted $1500 for her. I drove 2:15 to get there (Sacramento). 
Had been sitting for 7 years in a warehouse. They pulled her right out, drained the gas-tank (after trying to start with that crappy fuel). Put some race-fuel in the tank, hooked up the battery and after about 5 or so minutes of fussing, started right up. 


PICTURES (When I bought her)


She needs alot of work, fluids changed just to start. And both the throttle handle (grip and all) and the clutch handle (grip and all) need to be replaced too. 
The ECM and Fuel-pump had been replaced some time ago when the dismantler bought her. But they have never been used. I take it those both go for ~$300?

If so I probably got a $2100 (seven years ago) bike for $900. Did I say $900 above? Because that is what I was able to bargain for.


My goal is a Scrambler or something like this: 

Goal or Goal #2 


I have been an avid member at ADVRider for some years now, but never really had the wheels to do it. 
Id like to ride the entire HWY 1 (Pacific Coast Hwy) from California to the Canada border this Summer.


 Anyway I'm looking to probably take everything apart, rebuild the engine, paint and all- since I have no paperwork on previous mechanical work. 

I have no idea though on how to do simple stuff like changing the oil etc. (Since this is completely new machine). 

Looking for some friendly people and manuals...


Are these suitable?

http://www.motobrick.com/index.php?topic=2252.0  
or
http://service.tanga-moteurs.ro/data/BMW__k100%20%26%20k75%20Haynes%20Manual.pdf 

Not sure if those cover rebuilds and things like that but yeah im a newbie.

Looking forward to this. It will be fun!


good website?

http://verrill.com/moto/moto.shtml


Im picking her up sometime in the next 4-6 weeks. Id like to have some knowledge on replacing the fluids and buy them ahead of time.

-jjs1234

Welcome to the forum and congrats on your purchase.

There is a section on the home page on what to do if you have bought a K. Have a good read.

A few things, first don't run it. You may have been lucky and the guys cleaned out the gas tank. The gas pump inside the tank sits in a damper that breaks up and the bits clog the pump and gas filter. If they cleaned it out that's good.

If it was stored dry under cover then you should have a good bike.

The engines are unburstable and to be honest I wouldn't be dismantling the engine. You now know it runs. I have an ex BMW friend who in all his time from the first K never dismantled a K engine or even took a head off for maintenance, only crash damage. 47K is low miles. You don't do things like rebore them, the Nikasil lining means they cant be bored but they do last well. A performance tweak is to fit K75 pistons instead of K100 pistons, higher compression ratio.

Check out the timing chain and tensioners, if you want to feel really comfortable replace them, the kit isn't too expensive. While you are at that check the valve clearances.

The oil/water pump is another likely fail as it may be a bit corroded if it was sitting. I would be inclined to go the whole way with that, impeller, shaft, seals etc as it will fail in time and leak. The one shaft does both oil and water. Both of these jobs are very accessible, at the front of the engine.

The forum here has all the manuals and everyone is really helpful. We will throw the odd well meant wisecrack at you but you wont beat the help and assistance here.

Have a look under your engine, you will see a circular finned cover with 3 Allen bolts, that covers the oil filter, but you need a tool to remove the oil filter. The sump plug is near it. By your right foot, underneath you will see the round sight glass showing your oil level, centre dot on centre stand on level ground is your correct level.

The long cover across the front of the engine has the timing chain inside. The circular cover low down at the front of the engine houses the oil/water pump.

Rubbers perish, so replace the fuel lines, crankcase vent, check out the intake manifolds.

Probably start a thread for yours and then everyone will add in their bit. Don't ever be afraid to ask a question, we all started out somewhere.

If the engine is running OK and has under 300k miles then leave it alone. I would change the oil 1000 miles after the first change to get rid of the excess crud stired up and leave it at that.

jjs1234 wrote:
I have been an avid member at ADVRider for some years now, but never really had the wheels to do it. 
Id like to ride the entire HWY 1 (Pacific Coast Hwy) from California to the Canada border this Summer.

Welkome to the knuthouse.  

When you've done HWY 1 over there, come over to Australia and do Highway 1 over here, which is also the Pacific Coast Highway from Melbourne to way way up North.

Bill

92KK 84WW Olaf wrote:Welcome to the forum and congrats on your purchase.

There is a section on the home page on what to do if you have bought a K. Have a good read.

A few things, first don't run it. You may have been lucky and the guys cleaned out the gas tank. The gas pump inside the tank sits in a damper that breaks up and the bits clog the pump and gas filter. If they cleaned it out that's good.

If it was stored dry under cover then you should have a good bike.

The engines are unburstable and to be honest I wouldn't be dismantling the engine. You now know it runs. I have an ex BMW friend who in all his time from the first K never dismantled a K engine or even took a head off for maintenance, only crash damage. 47K is low miles. You don't do things like rebore them, the Nikasil lining means they cant be bored but they do last well. A performance tweak is to fit K75 pistons instead of K100 pistons, higher compression ratio.

Check out the timing chain and tensioners, if you want to feel really comfortable replace them, the kit isn't too expensive. While you are at that check the valve clearances.

The oil/water pump is another likely fail as it may be a bit corroded if it was sitting. I would be inclined to go the whole way with that, impeller, shaft, seals etc as it will fail in time and leak. The one shaft does both oil and water. Both of these jobs are very accessible, at the front of the engine.

The forum here has all the manuals and everyone is really helpful. We will throw the odd well meant wisecrack at you but you wont beat the help and assistance here.

Have a look under your engine, you will see a circular finned cover with 3 Allen bolts, that covers the oil filter, but you need a tool to remove the oil filter. The sump plug is near it. By your right foot, underneath you will see the round sight glass showing your oil level, centre dot on centre stand on level ground is your correct level.

The long cover across the front of the engine has the timing chain inside. The circular cover low down at the front of the engine houses the oil/water pump.

Rubbers perish, so replace the fuel lines, crankcase vent, check out the intake manifolds.

Probably start a thread for yours and then everyone will add in their bit. Don't ever be afraid to ask a question, we all started out somewhere.

Thanks for the advice. I did notice that when we filled the tank (partially) a puddle formed- it was leaking quite fast. 

What would you recommend if I wanted to repaint the engine? Or clean it?


So Replace:

-fuel line/fuel filter (and run some Seafoam)
-battery
-oil
-coolant
-transmission oil?/Final drive oil? (im reading: So you just bought a used BMW K-Series Motorcycle... by Ted Verrill)
-Spark Plugs
-Air Filter
-Spline Lube?
-Check the brake fluid/brakes...

G'day jjs 1234, 
youve arrived at the correct detination , welcome .
friendly people and extensive know-how in abundance .
enjoy .
N

jjs1234 wrote:
Thanks for the advice. I did notice that when we filled the tank (partially) a puddle formed- it was leaking quite fast. 

What would you recommend if I wanted to repaint the engine? Or clean it?


So Replace:

-fuel line/fuel filter (and run some Seafoam)
-battery
-oil
-coolant
-transmission oil?/Final drive oil? (im reading: So you just bought a used BMW K-Series Motorcycle... by Ted Verrill)
-Spark Plugs
-Air Filter
-Spline Lube?
-Check the brake fluid/brakes...

I just know that I want to treat it as if the previous owner did no maintenance whatsoever. 

-Check to see if the fuel/water pump is corroded...

Also buy:

Buy a manual

BMW Tool Kit

Oil filter tool

Take the gas tank off and pour some fuel in, shake and empty any debris?

Are the manuals I linked good?

Thanks so much

I'd replace/do all the above except perhaps the BMW tool kit. You could well find that putting together your own will be more comprehensive and cheaper than the BMW kit.
The spark plug leads are designed to work on a plug with the terminal nipple screwed on. Many new plugs don't come with them, so make sure you keep the old ones or get some new ones.

Some of the fluids may not necessarily need replacing, but not too expensive to be sure. Definitely engine oil, coolant and brake fluid.

For the fuel tank clean, remove the fuel cap assembly first - 4 phillips head screws. (You have to do that to get the fuel pump & filter out anyway.) Much better chance of the debris coming out with the fuel.

The manual from Motobrick (Frankenduck) looks like the factory manual - always better than the aftermarket ones. Haynes manual is useful, but has significant gaps, often where the info wanted is critical.
Download them both, look up anything you want on the computer, and print just the bits you need to take into the workshop if necessary.

Bill

As far as redoing the water/oil pump, is it something I should take the cover off and eyeball or just go ahead and do it? I read somewhere that if the impeller has a nut it is a old pump? And if it has a bolt it is a new pump? Also do I need to drain the Oil/Coolant before hand?

-Seals
-Impeller
-Bolt
-?

On Motobins (https://www.motobins.co.uk/bmw-parts.php?model=K%20Series ) ENGINE PARTS > OIL PUMP AND WATER PUMP 

I see 2 toothed gears, is that what I would be replacing? Seals, Impeller, Bolt and the 2 toothed gears? 






Thanks so much Indian!

Welcome,

i can give you a few notes on your Bike:

  Vehicle Identification Number 0050486
  Type
  Model K100rt - USA
  Development Code K589
  Chassis
  Steering
  Doors 0
  Engine 4-ZYL
  Displacement 1.00
  Power 66
  Drivetrain
  Transmission MECH
  Color Bajared Metallic - 578
  Upholstery Nicht Gemeldet - *
  Production Plant
  Production Date 1984-08-01
  Options
  749 La California La Californien

  Oil/Water Pump:
  Have a look at the shaft! If it is rusty (little wholes in it), it's broken. In this case, you have to replace the pump with (used) spare part...
  If the Shaft looks good, you only have to replace the Seals.
          
  Be careful! Parts of the seal are ceramic! Can be break easily!


have fun, Michael

jjs1234 wrote:As far as redoing the water/oil pump, is it something I should take the cover off and eyeball or just go ahead and do it? I read somewhere that if the impeller has a nut it is a old pump? And if it has a bolt it is a new pump? Also do I need to drain the Oil/Coolant before hand?

I see 2 toothed gears, is that what I would be replacing? Seals, Impeller, Bolt and the 2 toothed gears? 

Thanks so much Indian!

My pleasure, jjs. Just reflecting what I did with my own K100 when I bought it, and general mechanical experience.

Re the oil/water pump, I've never needed to work on one, so I'll leave it to those with more experience on these machines.
Generally, replacing gears is only necessary in case of a catastrophe but water pump impeller is more commonly needed from reading others' posts.

You will need to drain oil and coolant for this, so look at the pump while you have them drained anyway for replacement. While you're at it, check the water hoses for condition.

Bill

My RT is also 84, Baja Red, no 22575 from August 1984.

Looking at old water pump posts for the earlier ones [as in 84] you end up after you have gone that you find the shaft needs to be replaced as well. Even my ex BMW friend who did mine as I was too busy decided to buy the parts and then had to go get the shaft, even though I had told him do the shaft. Having bought the bits he then had to get the shaft to suit. My thought is buy the whole kit including the shaft. If you don't use it you can sell it on.

On the gas tank they are prone to pin holes from inside but they can be repaired. The spigots at the hose connectors can also get damaged if mishandled. There are also 2 drain spigots under the centre of the tank, don't damage these either. One of them is connected up to the little drain hole beside the filler cap and which must be on the left side so don't be tempted to reverse the filler cap. Front left of the gas tank the electrical connector can get a bit lose. Close up the four female ends inside the plug just a little to make sure you have good mechanical and electrical contact with the male pins on the underside of the gas tank. The 749 Californian reference may have the Californian gas tank vapour emission set up, I am not familiar with the workings of that.

The warning about he ceramic seal is important. As a side note when mine was done there was a small drip immediately afterwards/ My friend said to keep an eye on it and if it persisted to come back. It dried up and all has been fine since.

You may well get by not doing it. Run it first with the new fluids and see how it goes but...that original impeller can disintegrate to the point of being ineffective. Trying to replace the impeller on its own, theoretically possibly seems to mostly go wrong.

jjs,

Looks like your 1/8/1984 bike is the first of the 1985 models. 

For the toothed gear you will need the one with part number 11535 (it is expensive).  This one has the 19 teeth on it and the later one from 1990 had 32 teeth.  The smaller gear is not required as it will be fine.  If the shaft of 11535 has any corrosion (rust) around its circumference then best to replace. 

The photo of the five piece kit has the ceramic water seal at the top (the one with the blue ring on the side).  Buy two, yes buy a spare.  You will thank me later.  The little black o ring goes on the end of the smaller toothed gear.  You will see it when you pull it out. 

The black seal (lower right) is the oil seal.  It gets bashed (with a socket) into place on the water pump housing.  The bolt and impeller with both be required due to the age of your bike unless the water pump has been repaired before.  The older design is not much use, not even for a paper weight. 

There are a number of tutorials on how to do them.  If it has not been done before then there will be a bit of crud inside that needs cleaning. 

The easy option is to buy a complete water pump but hey, that takes the fun out of being a K owner.     It could also be one way of offsetting the dreaded K pox .....

Can you post up a photo of what you got. The Google photos are not accessible to all of us. As I mentioned I have K100RT 22575 as August 1984, your number is much higher. Photo will help.

The 2 'goals' are different models first one being 8 valve and 'Monolever' final drive. Very early Monolever final drive to drive shaft is a 16 spline shaft, later is a 20 spline drive shaft so be careful if you are in there.

The second one looks like a 16 valve as it has the later footrest hangers and has the drive train [Paralever] etc of the 16 valve. This conversion can be done to the 8 valve if you want to go there.

Hello!

The old water/oil pump has a cast iron flywheel.
The picture shows on the left side the old pump and on the right sight the new pump.


Replacing the water/oil pump seals
https://www.k100-forum.com/t1070-replacing-the-water-oil-pump-seals

Cheers

Welcome!  It looks like you have fully activated the support network here.  Am looking forward to your getting her on the road and tales of adventures on Highway 1.

Regarding the fuel puddle, these tanks are notorious for leaks caused by aluminum corrosion.  It normally occurs at the low spot just behind the badge where water in the fuel can sit and work on the metal.  There are several fixes, including various epoxy patches that can be applied.  Personally, if it were my bike, I would look into having a weld repair, or possibly this stuff(http://durafix.com/index.html) a copy of which I believe can now be found at Harbor Freight.  Just be sure to drain and dry the tank thoroughly before putting a torch to it.

Speaking of Harbor Freight, they have some very nice Allen Key sets and torque wrenches which are frequently on sale.  I have two of the torque wrenches 1/4" and 3/8" and they are very accurate.  Well worth the $28 I have invested in the two of them.

Another point, get a can of DeOxIt.  You can find it on eBay.  Keep it close at hand and give every electrical connection you come across a quick shot and a couple connect/disconnect cycles.  One of the main problems on these old girls is corrosion in the electrical connectors.  Being proactive is the best defense against operating issues on these machines.

Moderators, since this thread has already ascended into repair discussions, perhaps it can be transferred to the projects section with a new title so as to avoid starting a new one.

Chocolate wrote:Hello!

The old water/oil pump has a cast iron flywheel.
The picture shows on the left side the old pump and on the right sight the new pump.


Replacing the water/oil pump seals
https://www.k100-forum.com/t1070-replacing-the-water-oil-pump-seals

Cheers

Thanks Chocolate for the link

Hey 92kk here are your pictures you requested:

92kk wrote:Can you post up a photo of what you got. The Google photos are not accessible to all of us. As I mentioned I have K100RT 22575 as August 1984, your number is much higher. Photo will help.

The 2 'goals' are different models first one being 8 valve and 'Monolever' final drive. Very early Monolever final drive to drive shaft is a 16 spline shaft, later is a 20 spline drive shaft so be careful if you are in there.

The second one looks like a 16 valve as it has the later footrest hangers and has the drive train [Paralever] etc of the 16 valve. This conversion can be done to the 8 valve if you want to go there.

I have no idea what a Monolever is. Your talking about the drive-shaft correct? You mean be careful if I decide to redo the lube in there? 

Edit: I see you were referring to the GOAL pictures I posted. Okay thanks for the info  

Is the later Paralever more reliable or is it just Apples & Oranges?


So far I have bought all the Oil (I was tempted to go semi-synth), filter and gear oil. The full kit. 
Also bought a clutch lever with the switches as that seems to be missing. 

So that tank leak is caused by two things that I have read:

-bad O-ring
-holes in the tank...

I will go to Autozone to pickup some more things. RTV is required for this im guessing, since I didnt see any gaskets. Dielectric Grease, some other stuff: DeOxIt


On another off-topic note:

I heard running higher octane cuts down on vibration and it runs better?

Also I am a bit curious as if this model has the California Cams or Euro Spec. But that was initiated in 85, and technically I have the 84...


Thanks so much for the info guys! 

Yeah so much for the intro- this just became the thread I was going to create!

-jjs1234

You have a Monolever swing arm.  That is the standard for all the older K bikes.  Don't worry about Paralever.  That didn't come out until the 90's with the K1.

jjs1234 wrote:
....

On another off-topic note:

I heard running higher octane cuts down on vibration and it runs better?

... higher than what?  With modern higher performance engines, you'll get pre-ignition with low octane fuels (wasted fuel, vibration etc).
BMW recommend a minimum 91 octane for the K. I use 95 mostly and sometimes 91. I keep accurate fuel consumption records and I see no real difference between these. However, my best fuel economic runs have been on 91 octane. What I stay clear of is anything with ethanol in it and the cheaper independant fuel outlets. I've picked up some crap fuel from some of these.

Ah okay. For a second I was thinking 89 but its 91. Its kinda hard to find fuel without the BS mandate of 10% eth...

The Feds here in the states are easing up on the sale of corn-free gas.  There are web sites you can use to see where the real stuff is being sold.  Station owners are finding that corn-free 91 octane generates a lot of traffic from the motorcycle, high performance and vintage car owners and can justify putting in the tanks and pumps for it.  It costs a little more, but it's worth it, especially when I am putting the bike away fro the winter.

I wont use straight 91 especially in the K75 or K1100. 11-1 compression does not like the low octane and Nicasil bores don't get along with detonation. I use 98 if I can or 95 and 3rd choice is 91 with 10% ethanol because the ethanol will not detonate any where as much. I always run the ethanol out as soon as I can.
BTW .75 I see you are getting a big blast from the arctic at the moment.

Rick, I think there are different octane rating systems between our countries.  Perhaps TWB can comment.  For example, here in the U.S. BMW specifies the use of 87 octane or higher.  I have no problem running 87 in any of my bricks.  I use the 91 which is corn free only because I have found that E-10 is rather hydrophilic and the water can separate out causing corrosion problems.  It's also tough on plastic and rubber.  The higher octane rating of the corn free is a bit of a bonus, but isn't really necessary.  I've never had any preignition with any of my bricks, even when I've run 87 octane in temperatures up to 95F.

Here they recommend 95 for the cars and bikes so from that it seems the 95 here is the equivilant of 87 there.
I use the 98 almost all the time and when I di fill with 95 I notice a small difference in performance plus about 1 extra mpg on average.
One thing I did get told was that following me a friend could tell when I was using 95 because the exhaust smelled a bit but that could be just tuning.

Hi guys, interesting reading the discussion re octane ratings in USA versus OZ. I had a quick look at good ol' Wikipedia and found the info below at this link.

It suggests that the different method of nominating the octane rating results in a 4 to 6 number difference.

Measurement methods[edit]

Research Octane Number (RON)[edit]

The most common type of octane rating worldwide is the Research Octane Number (RON). RON is determined by running the fuel in a test engine with a variable compression ratio under controlled conditions, and comparing the results with those for mixtures of iso-octane and n-heptane.

Motor Octane Number (MON)[edit]

Another type of octane rating, called Motor Octane Number (MON), is determined at 900 rpm engine speed instead of the 600 rpm for RON.^[1] MON testing uses a similar test engine to that used in RON testing, but with a preheated fuel mixture, higher engine speed, and variable ignition timing to further stress the fuel's knock resistance. Depending on the composition of the fuel, the MON of a modern pump gasoline will be about 8 to 12 octane lower than the RON, but there is no direct link between RON and MON. Pump gasoline specifications typically require both a minimum RON and a minimum MON.^{[citation needed]}

Anti-Knock Index (AKI) or (R+M)/2[edit]

In most countries, including Australia, New Zealand and all of those in Europe,^{[citation needed]} the "headline" octane rating shown on the pump is the RON, but in Canada, the United States, Brazil, and some other countries, the headline number is the average of the RON and the MON, called the Anti-Knock Index (AKI), and often written on pumps as (R+M)/2). It may also sometimes be called the Posted Octane Number (PON).

Difference between RON, MON, and AKI[edit]

Because of the 8 to 12 octane number difference between RON and MON noted above, the AKI shown in Canada and the United States is 4 to 6 octane numbers lower than elsewhere in the world for the same fuel. This difference between RON and MON is known as the fuel's Sensitivity,^[4]and is not typically published for those countries that use the Anti-Knock Index labelling system.

All I will say to that is don't try to start or run your Harley on any of that lot because the glow plugs will ignite the fuel that dribbles out of the injectors and the damn thing will catch fire again.

92KK 84WW Olaf wrote:
The engines are unburstable and to be honest I wouldn't be dismantling the engine. You now know it runs. I have an ex BMW friend who in all his time from the first K never dismantled a K engine or even took a head off for maintenance, only crash damage. 47K is low miles. You don't do things like rebore them, the Nikasil lining means they cant be bored but they do last well. A performance tweak is to fit K75 pistons instead of K100 pistons, higher compression ratio.

Hey 92kk, I did want to ask you about this. I was casually searching for parts for my upcoming rebuild as it appears that on my deeper inspection of my bike on this thread here, Robmack based on my pictures mentioned this:

Robmack wrote:robmackYou've got some issues with oil / coolant leaks.  Also fuel pump surround, fuel lines, crankcase vent and maybe other stuff

- oil on the sump bottom is probably a leaking water / oil pump seal.  You'll need a new seal kit or find a replacement pump (second option might be easier)
- oil coming out the weep hole on the bottom of the bell housing indicates one of two possible problems.  Pick up a drop on your finger and smell it.  if it smells sulphur-like or is very pungent, you have a leaking input shaft seal on the transmission.  If it is mostly odor-free or smells like motor oil, it's a leaking O-ring on the main output shaft most probably. Either problem means you're going to have to tear into the transmission / clutch area to fix.
- crankcase vent pipe is the Z-shaped rubber hose going from the air box to the crankcase. It needs to be replaced as other have pointed out.
- fuel lines have to be replaced as others have pointed out
- The fuel pump surround may be degraded by the evidence of rubber bits lying in the bottom of the tank.  There are two clips that hold the pump in position.  Squeeze the clips to extract the pump and examine the rubber surround for deterioration.
- The staining of the temperature sensor connector and the timing chain cover might be a coolant leak coming from deteriorated rad hoses, not necessarily a broken rad core..  Examine all of them and replace those that are bad.

While it doesn't seem that I need to disassemble the engine, I believe I will need to drop it. 

In any-case I was wondering if putting the k75 heads in a k100 is a viable option. You do mention it but I ran into this thread here where forum member "Two wheels is better" posts about it.

Now I guess my question is...

Is this a simple swap? Or do things need to be adjusted to make up for the greater compression etc. 

Putting the K75 pistons in a K100 is a simple proceedure if you are familiar with that type of engine work. The head has to come off and the crankcase cover but the engine can stay in place. They are a very easy engine to work on. The compression goes from 10.2 - 1 to 11 - 1. You shouldnt need to do any adjustments.

and you wont need to take the motor out of the frame even

wish I had done it when I did my pull down - rebuild

good luck