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Cheap Stuff to do to BMWs

Discussion in 'Modifications and Projects' started by PatB, Jun 4, 2013.

  1. Inspired by a trip to a Historics meeting on Saturday and the subsequent discovery of this website, I've decided to pass a few hours fiddling about with stuff related to Project K200, my intended lightweight BMW K100RS trackday/P6/Rule 20 weapon. I'm beyond skint at the moment so anything to be done has to happen with either zero material input or with whatever I have in stock. That rules out seriousrebuilding or replacement of mechanical parts but there's a shitload of stripping and cleaning to be done so I might as well have at it whilst I've got the time.

    First patient is the fuel tank. Here it is after a fairly hard 20 year life, followed by kicking around my shed for almost a decade.

    Tank Before.JPG

    Don't be fooled by the quite flattering photo. The paint job is a dodgy amateur effort over what was originally silver. At least I hope it's amateur. The other alternative is that someone actually got paid to apply Bunnings gloss enamel over a coating of dead insects. With a stick.

    Here's my evidence for thinking this tank originally came from a silver bike.
    Tank Before-Underside.JPG
    As you can see, where the eye don't see, the tank ain't black. You can also see that the insulation on the bottom of the tank is in reasonable nick considering its age. I'll be leaving it in place, at least for now. There's also a residue of old petrol leakage around the various nozzles and take-offs where there's been 20-odd years of oozeage.

    First step is to pull the filler cap off to give us access to the inside.

    Tank Cap.JPG

    Four Phillips screws and the whole cap assembly lifts out, revealing a surprisingly intact squidgy plastc seal,

    Cap Off.JPG

    the fuel pump for the efi,

  2. the filter,


    and a forest of breather pipes.


    A few minutes mucking about with an 8 mm socket on a weeny ratchet and the pump is out.

    Pump Out.JPG

    Had I bothered to read the manual, I'd have found out that I could have just unplugged the thing and dealt with the little nuts in comfort on the bench. Ah well. I was also interested to note that the manufacturing date on the fuel filter was some time in 1987, suggesting a previous owner with my own approach to efi filters. Thing is, there's no real excuse on the K 'cos it's easy to change the filter through the filler cap aperture.

    Anyway, we're left with a big 'ole in a baffle where the pump used to sit

    Pomp Ole.JPG

    and a surprisingly small pile of crusty shit, considering that the tank almost certainly hasn't been cleaned in close to 30 years.

  3. Oh goodie, this should be interesting for sure. My Dad really likes his K's.
  4. Last task for the day is a coat of pickle juice.

    Pickle Juice.JPG

    Seriously though, it's some brake fluid I've had sitting on the shelf for five years with the seal off, rendering it too dodgy even for my lackadaisical approach to mechanics.

    Legal note: I am a trained professional idiot and so am able to get away with putting a toxic substance into a food container with no more ill effect than finding that the pickles taste funny. If you try the same thing and die that's your problem, not mine. Frankly, if you can't tell the difference between pickle juice and a disturbingly blue, glycol based fluid that tastes almost as revolting as alcohol free mouthwash long before you've ingested a lethal dose you're probably better off out of the gene pool anyway.

    Hopefully, by morning, at least the first layer of paint will have bubbled up nicely ready to be scraped off and disposed of responsibly by lighting a fire with it.
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  5. Lightweight K100RS? But surely those things are already light.

    Look forward to watching the project with interest.
  6. Book weight is 239kg dry. Aim is 200kg dry. Road gear and bodywork can go which, given that BMW fairings are carved from solid granite, gets me a decent chunk of the way there. That's the nice thing about pruning weight on a BMW. Everything is so massively constructed that anything you replace it with will be lighter. Even the bloody footpegs are a kilo or so each due to the anti-vibe weights.

    Don't expect rapid progress though. I've been farting around with this bike for four years off and on (more off really) and it's still mainly a random heap of knackered parts.
  7. Find a way to ditch the shaft,that will save a few k's.
    Might be exy but.
  8. I'll watch this with interest for two reasons
    The obvious one is mechanical, love watching the 'before and after' pics
    The other is that with the infrequent incursions of the Chairman, pat has the finest turn of phrase on Netrider!!!
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  9. watchin too
  10. Oh PatB, what happened to you man?

    I reckon setting it on fire would be the cheapest mod, probably save a bit of weight too! :LOL:

    Of course, I jest & look forward to further updates.
  11. Old K bikes.. Concentrate on the basics. New filters and oil. Won't hurt to whip the shaft out and use some Optimol white T paste on the shaft splines. Drain and change the diff oil. You'll usually ditch a hand full of metal filings out of there. No idea where they come from, but they always seem to be there.

    Simple mods, a length of air condition pipe insulation and a roll of electrical tape. Wrap every last bit of fuel line and the fuel rail. K bikes run fugg'in hot. The early 1985's could get hot enough to boil fuel in the tank. Also worth checking the under tank insulation. The Mothership upgraded the heat pads in about late 1986. Buy some new ones. They're reasonably cheap. Keeping the fuel cooler will give you some gain for peanuts spent. If your keeping the fairing, stuff the remaining insulation into all the knocks and crannies to get the hot air blowing out through the "shark fins" vents on the fairing. For those silly enough to ride an RT ( Road Toaster) on a hot day, this stops you from getting cooked and improved air flow.

    Check the cooking fans on your bike as well. They usually die after 20 years or so. ;) not hard or expensive to replace. The injectors are the same Bosch ones found in mid 90's Camrys. Check the serial numbers and swap them if needed. Making sure they're clean will give you some extra for cheap. Spend $20 on done good spark plugs. Old K bikes run like crap in dirty plugs. They also don't seem to need much fowling compared up Jap bikes to run like crap either. What would seem normal on a Honda will make you think the engine needs rebuilding on a K100.

    The biggest fault with these bikes is lazy morons who use the side stand. The side stand is only there to let you get off. BMW's should ALWAYS be left on the centre stand. It stops the oil running up in to the exhaust valves and the head generally, then fouling everything and being blown out the exhaust.

    Once you take care of the basics, you can move forward from there. Basics should cost less than $200. Munich Motorcycles does a service kit with all filters, O rings and plugs for about $130.
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  12. Alternately if you really want to use the side stand lean the bike to the right for 10 seconds or so, that worked well with my K and still does with the R65LS. However be aware that another good reason for using the centre stand is that older side stands are the least well engineered BMW parts and have been known to give up the ghost.

  13. Thanks. All good advice. I think I've got most of that covered as my other K100RS was my daily commuter for 100,000 km which gave me a good grounding in their care and feeding, including suffering a spline failure shortly after I got it, and needing a replacement rad fan (which was cheaper than the equivalent component on a GPX250 BTW).

    It also broke two centrestands, leaving me with no choice but to use the sidestand at times. Fixed that with a used 16V stand which bolted straight on.

    As this project is for the track only, it will have no stands and probably no rad fan, given that it will not be encountering any traffic jams.

    Interesting tip on the injectors. I knew they'd be interchangeable with something but couldn't find any data on what. Given that it's possible to get old Camrys for less than the price of a set of injectors at BMW prices that's very handy indeed.

    I may end up using the engine and trans from my other bike because the engine on the project basis has the doomsday knock from its output shaft and the gearbox has something wrong with the selector mechanism. I think I know what it is and how to fix it at zero cost but if I'm wrong...............Hence I'm treating the engine/gearbox unit as an assembly jig/source of spares rather than worrying about condition right now.

    Thanks everyone.

  14. Quote of the Interwebs
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  15. The knock is the rivets coming loose on the gear on the lay shaft. They bag and thump, but never heard of them actually failing. If your in the gearbox at any time, a punch will shut them up, but personally I think a K bike that doesn't knock doesn't sound right.

    The injectors used in the L-jetronic injection are pretty common. They used them in everything from Porsche 944's to Camrys. I know last time I went to replace a set in my old RT, surprisingly they were cheaper in a genuine BMW packet Via Munich Motorcycles or MotorBins. Everywhere else were far more expensive, by up to double. Because they are so common, they are really cheap to have rebuilt and cleaned.

    If you know K bikes, its also worth checking the water pump for leaks. If you want to dump at least 5-8kgs, drop the stock exhaust. You will need to find someone with a welder and a BFH to make an aftermarket fit.
  16. And here we are again after another coupler of hours' work.

    Bloody brake fluid did nothing. At all. Well, alright, it softened a bit of paint round the filler aperture which was quickly scraped off.

    No Effect.JPG

    So, having removed approximately 1% of the paint and having nothing in the budget for proper paint stripper we're down to the mechanical removal of the stuff. Let's have a lok at the weapons of choice.

    Weapons of Choice.JPG

    From left to right we have a 60 grit flap wheel in an air powered die-grider, an orbital sander with bear's arse grade paper on it and an angle grinder with a wire brush on the end.

    All have ther pros and cons. The die-grinder offers excellent control, gets into tight corners and leaves a decent surface finish but is slow, uses huge volumes of air so the compressor runs all the time and, for some reason, attracts the dog who puts his pointy little nose about 5mm from the whirling abrasive. The sander won't do concave areas and any coarse enough paper to get through the paint in a reasonable time leaves a crappy finish on the underlying ally. It is, however, marginally less noisy and messy than the other two. The wire brush on the angle grinder is fast and doesn't chew up the ally too badly but it tends to melt the paint layer into a hot, tarry goo which it proceeds to smear across the surface and throw around the work area in roughly equal quantities. It also throws out wire splinters with some enthusiasm so eye protection is even more vital than it might otherwise be.

    What all these tools have in common, though, is that they're noisy, messy and mildly dangerous. After a couple of hours of work I've got an incipient headache and a good coating of black snot in my nose. Pretty much inevitable with mechanical paint removal. Regardless of the claims of numerous magical inventions over the decades it's always a noisy, shitty, horrible job that's easy to abandon halfway through. I hate it.

    Here's the tank after a go with the sander

    After the Sander.JPG

    and here it is again at stumps on day 2 after I tok out my frustrations on it with the angle-grinder.

    State of Play.JPG

    Just the edges, corners and badges to deal with. I'm really glad that's nearly over. Then I have to put a decent finish on it. I'm not after a high polish, just a reasonably smooth, burnished look. There's a limit to how much it's worth doing. Once all the paint and filler are off, the surface is surprisingly lumpy with raised seams, stamping marks etc. all over the shop, not to mention decades of stone chips and minor dings. It'd look like crap with a mirror finish. I forsee lots of hand work with various grades of wet & dry.
  17. With the cost of electricity these days,paint stripper may have been cheaper than the sander.
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  18. Has anyone else noted the dichotomy between this thread and Pat's signature line? ;)
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  19. Have seen this said numerous times about old K series bikes but never about Rs.

    However on the rare occasions when I rode the R100RT to work in summer I had to park it on the side stand. In the summer sun the centre stand used to just sink into the bitumen and the footpath outside work is pockmarked from when I tried. Had a couple of occasions when it had sunk so deep that I barely managed to get it off the stand because it involved lifting the entire bike to the higher level of the surrounding footpath. Also one day I came out to find that one side had got more sun than the other and the bike was on such a lean that it was perilously close to falling over.

    However parking it on the side stand was embarrassing as I had to fire it up in pedestrian peak hour just as thousands of commuters were making there dash past on their way to the station and some of them used to get lost in the ensuing blue cloud. A number of times the only thing which saved me from an angry lynch mob was that I managed to escape while they were still trying to find anything resembling oxygen in the smoke.
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