hi folks just new here, currently looking at purchasing a BMW k100 i have found cheap and hoping to learn a bit in a quick space of time to help me decide. i have a long background in dirtbikes....
look forward to chatting to some more knowelegable folk about these bikes after i have done some background reading so i dont ask previously answered questeions, 
cheers.

Welcome from another Aussie, though temporarily in France.

You've probably noticed that there is a lot of expertise here, so you're in the right place.

We can help best if you tell us what you know about the bike you are thinking of such as year model/variant, whether it is currently running, and if not, what do you know about when it last ran and was last registered, and also if not running, its storage situation in the intervening time.

You can also get some clues to look for by clicking on the portal tab, then You just bought a used K100, so what now?


Best wishes,

Bill

Hi and welcome.  I'm only slightly ahead of where you are now having made the same purchase a few months ago.  There  is so much here to learn from and it all goes toward the best part - riding a really fantastic motorbike!

ok, would love to hear some thoughts....
not sure exactly which model other than build date is 83 and has basically no faring compared with others i have seen.
its been sitting covered in a shed for years, but has little corrosion or signs of weathering, and is clean , tidy and compleate, except the fuel cap.
the bike cranks over but wont fire and i cant hear any fuel pump running so thats the first thing i gotta try to nut out.
i can get this bike for a steal ($700ish aus) but im still not sure. i could be looking at wrecking it or just trying to get it going and passing along, or possible a scrambler conversion as i am a dirt bike kid a 1000cc dirt bike sounds like fun.... 
open to comments.

Only you can make the decision, but my 2 cents worth would be to go ahead at that price. Proviso is that you have some mechanical competence and willingness to learn some electrical/electronic stuff if you don't have those skills already. Good people here to learn from.

At '83 and with no significant fairing, its likely to be a basic. Round headlight? In your north Queensland neck of the woods, likely a better prospect than an RT or even an RS. Full fairing is great in the rain, but not so good in the heat.

Sitting unused for significant time means some rubber/plastic based components may be degraded, and some work will be needed to get it running and satisfactory. Don't expect to spend a couple of hours on it and all will be well. A well sorted one is very rewarding to ride, though. 

Scrambler conversion is an item of some differing opinions here. If the bodywork around the headlight and radiator is still OK, many would be sad to see it anything other than substantially original. Even the 'original' purists are OK with scrambler/café racer etc. for one that is already pretty trashed in the body, just to see another K back on the road, but cringe and cry if a good one is converted that way. That said, your bike, your choice.

Let us know how it turns out.

Bill

hey bill thanks for your interest.
i know my way around dirtbikes fine, up engine rebuilds and suspension revalving but i would have a lot to learn about fuel injection and multi cylinder engines....
after seeing this bike, and how good a nick it is in, something positive should happen to it rather than to continue to live in a moist shed....
even if i just buy it and pass it onto someone who can get her going would be satisfactory to me me, as long as i can make it worth my while obviously....
i'll have to get back out to it and take a few photos but for a bike of its age its very neat, not even a tear in the seat....
do you think there would be much of a market for parts for these bikes? , worst case scenario i could wreck it as tank is dint and rust free, plastics are all good, doesnt ever look to have been dropped or anything and only 100,000 km on the clock which i understand is the run in period for these bikes

looks like this one....

Hi Tyson welcome to the Knuthaus
It would be a real shame to see an original 83 Basic broken up.
What is the frame number. Right side on the frame directly above the footpeg we can tell a lot from that.

WelKome to the forum Tyson. That's an early model 'Basic'. Would be interesting to have the VIN.

There's a lot to be said for buying a going concern. A K-bike that's been sitting for a few years will definitely have some issues to work thru. However, a 'basic' in good condition would be well sought after. I would not suggest parting this bike out at all.

Here's what you could be up for.
Refurbing the inside of the tank could cost up to $250 if parts are needed and that's very likely. Pump ($80), vibration damper $50, possibly a pump mounting, fuel lines ($20), filter ($15), and that doesn't include the possibility of a second hand fuel level sender.... if you can find one.
Take a look inside the tank. If it looks like a black mess then all the rubber parts have disintegrated. It'll need a bit of cleaning.
If the tank has had some water inside then you may have a bit of corrosion in the very bottom corner on the left. Have a good look for any slight blistering in the paint in this area.
Anything made of rubber will likely need replacing. Throttle body rubbers, crankcase breather tube and a host of seals, o-rings and grommets.
Injectors will likely need a good cleaning as they don't like to be left sitting around, and if one or two don't scrub up then you'll need a new set. There are a few options as the oem injectors are no longer available.
If the tyres are old, you'll need to replace them. There's a date code on the side.
For sure you'll need to pull the gearbox back to grease the clutch splines. Probably best to pull the gearbox off altogether and check the clutch and replaced the main seal and o-ring while you're at it.
An old bike like that there could be a bit of wear on the FD splines which seem to get chewed out if not looked after.
Check the steering head bearings ($100). Its a reasonably big job.
There are 2 weep holes. One under the water/oil pump at the front and another under the intermediate housing. A bit of oil misting here will mean seals/o-rings will need replacing. That may be hard to see if it's been sitting for a while.
In the absence of any recent service history, I'd be inclined to replace the timing chain and guides as well as the front crankshaft seal behind the timing rotor ($140).
Brake master cylinders may have some corrosion from water absorbed by the brake fluid over the time its been sitting.
Take a look at the brake rotors. They can cost you $200 to $350 each. Pads about $30 a set.
You could add another $200 for service consumables. Oils, filters, coolant, spark plugs, spline lube.

There are all sorts of electrical issues you could find, but you may be lucky.... or it could turn into a labour of love.
One thing is for sure. If you go down that road you'll be walking a well worn path. There are many stalwarts here with the knowledge and experience to help. The end result will be a bike that will treat you very well.
Cheers

thanks for the replys
details to come...
i looked in the tank, a bit of minimal lacquering but no rust or nasty looking stuff...
forks have no signs of pitting or rust but a bit spongy.... rear shock is not quite as nice but seems servicable.
engine sounds fine turning over, no noises, clutch works, gears engage fine.
most dash lights come on, and handlebar switches seem serviceable, horn etc work fine.... 
no signs of being dropped or undue abuse, tyres good, forks recently honed, ....
seat isnt torn but "collapsed" a little.
all rubbers except two small vacuum hoses look in good condition, with no cracking but they do look hard.... 
engine has seemingly fresh oil in it but no coolant i can see in the overflow bottle at least......
i have a week to decide/ play around a bit to find out more......

RicK G wrote:Hi Tyson welcome to the Knuthaus
It would be a real shame to see an original 83 Basic broken up.

Hear, Hear!

If you decided to pass it on and I bought it, I'd be afraid of being ambushed by several forum members on the way south. It mightn't arrive home!

As Holister said in more detail than me, There is likely to be significant work required, but your experience will translate well, and multi-cylinder is just a single repeated, mostly. The K is easier to work on than most because of the engine layout. In many ways its more like a car than a bike.

All the best as you consider.

Bill

guys, thanks for being so friendly.
and with the enthusiasm that is being show, i think my plan is:
go and get some good photos, vin etc, and post em up.... 
see if can wrangle the price a fraction more, even though its cheap (if it was a dirtbike of similar condition of similar age it would be seriously cheap, thats what i know.... lol).....
have a play around with it, see what i can learn..... maybe/ hopefully get it to run,-----
and if all else fails, hope i can find a good home for her , make a bit of beer money, learn a bit, and save a nice old bike.... 
sound fair...?

Sounds like a plan. I would've thought about $500 max for that but I'm not too sure about the intrinsic value of it being a Basic model.
Any history from previous owner/s would be handy.
Get the date code off both tyres as well.
Make sure she has coolant before you try to start her up

The fuel pump will only run when the engine is turning. (like when starting or running) Put your ear to the left side of the tank while attempting a start to see if you can hear it.

If the fuel pump isn't running you can tell if it's getting spark by pulling the air intake off of the right side of the air box (it's just mounted in a large rubber grommet so pulling it out should be easy) and spraying in some starter fluid.  If it's getting spark then that should make it run for a few seconds.