198X R80RT Stuff: Sprockets forum: Grassroots Motorsports Magazine

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Aug. 21, 2009 6:39 p.m. Stuc HalfDork

Well! I sure never thought I would be posting here, I'm more of a 4 wheel person but! I inherited a 198X BMW R80RT that needs a little work and I thought you guys might be able to help lead me in the right direction.

From what I've been told it's a we think 1984.

My mom dropped it a couple times but it still ran. I heard right now it just needs a battery, gas drained and maybe the carbs rebuilt since it had the ethanol fuel sitting in it for 2 years. We believe the fuel lines were updated but we're not sure about everything else.

Anyway, I know my way around a car pretty well now... but then realized I'm not sure how to tell if this thing is in gear, and if it is, how to change it. From what I can tell the mechanics overall are pretty simple, but I'm going to need some guidance fixing the fairing, etc.

Hopefully I'll be able to get you guys some pictures.

So my question is... I don't even know! Where to start, I suppose. Are there any good guides for this bike? How do the fuel systems take to the new fuel?

Thanks, -Stu
Aug. 22, 2009 1:41 a.m. confuZion3 SuperDork

I can tell you how to find out if it's in gear. Try to push it with the clutch out. If it moves easily, it's in neutral. If it doesn't, it's in gear. Most bikes have a neutral light as well that will tell you when the bike is in neutral when the key is on.

If it is in gear and you want to select neutral, press down on the shift lever a bunch of times to get it to first gear (the very bottom selection). Then, pull the shifter up a half-click until you just hear the transmission make a sound. You might have to rock the bike back and fourth a few times to get it to row through the gears.

Unless the fairings are in bad shape, I wouldn't worry about fixing them now. You will more than likely drop the bike yourself a few times--maybe even before you ride it (like, when moving it around the garage).

Buy a battery and try to start it. If it runs, great! If not, I'd start with the fuel tank. I tried to get an SV-650 started for a month with my brother. We tore it apart, cleaned the carbs, changed the fuel lines, and even lit it on fire. Nothing worked. Finally, I took a simple vacuum-operated petcock valve off, hit it with a screw driver a few times, and got it to open. It was stuck shut. A $5.00 part was keeping fuel from reaching the entire fuel system. After that, it ran beautifully.

Start with the tank and work your way down from there. The tank is where all the fuel will congeal.
Aug. 22, 2009 8:18 a.m. 914Driver SuperDork

Stuc wrote:

Well! I sure never thought I would be posting here, I'm more of a 4 wheel person .... Thanks, -Stu

Need a BMW? (car)

Here's a link to my local BMW Bike Shop; on the left side click "Parts Catalog". They have micro-fische like schematics of the bike and all of its components. This will give you an idea how things come apart or go together.

http://www.maxbmwmotorcycles.com/

http://www.maxbmwmotorcycles.com/fiche/MainDiagrams.asp?mospid=47877

Dan
Aug. 24, 2009 11:58 a.m. alex HalfDork

The 10th digit of the VIN corresponds to the model year (different, sometimes, from the date of manufacture), beginning in 1980 with the letter A, like so:

A = 1980, B = 1981, C = 1982, etc through Y = 2000; then 1 = 2001, etc.

For the record, the letters I, O and Q are never found in a VIN.

The last 7 digits are the BMW serial number, which you can use for parts lookup. (That Max BMW fiche above is the one I used daily as the parts manager at an independent BMW specialist. And Max BMW, in general, is a great shop, with a friendly and knowledgeable staff.)

On the headstock of your bike, there's also a VIN tag with a month/date of manufacture. BMW made lots of mid-model-year changes, so don't be surprised if you need to know that month/date combination to get the right part on occasion.

I highly recommend BMW factory parts, in the majority of cases. On average, they're not all that much more expensive than aftermarket (there are a few headscratchers, but plenty of stuff is surprisingly cheap, too), and you know they'll work. BMW is great about long-running support of its vehicles, so you'll be able to gte just about every little thing for your R80 direct from a dealer.

Good luck.
Aug. 24, 2009 12:13 p.m. BoxheadTim New Reader
Couple of suggestions from experience dealing with airhead beemers that stood for a while:
- Drain the tank and if there are any traces of tank coating in the fuel (run it through a coffee machine filter or similar), you'll need to reseal the tank unless you fancy cleaning the carbs every five minutes. The coating looks like red oxide paint but AFAIK isn't. The dust from the coating is often fine enough to pass through an average fuel filter. As I found out...
- Carbs on these tend to leak if the bike stood for a while. Conveniently, they tend to drip gas right on your boots. Pull the float and float valve and have the carb body cleaned in an ultrasound cleaner. Check that it shifted the red oxide coloured stains on the float valve seat if there are any
- Carb diaphragms don't seem to like standing around, but they're cheap. Definitely pull the carb tops and check them for tears or holes. Any of them, however small, and you'll need to change them.
- The big 'crown' nuts that hold the exhaust in place tend to corrode on. Make sure you have the special spanner to remove them and if in doubt, sacrifice the nut before you risk to damage the exhaust thread because that's a head off job and more expensive than the nut.
- Battery - they're big and expensive. If you want to keep the bike long term, stick an Odyssey (sp?) battery in. They're expensive, too, but they last longer
- Yes, the brakes are that bad
Aug. 25, 2009 11:11 a.m. motomoron Reader

I actually know everything there is to know about these. I'll admit it. I rode these things forever, even when I was roadracing real motorcycles; I worked for a BMW specific parts place years ago, and later ran the parts department and did vehicle sales for a BMW dealer. I was "The airhead boxer guy". In fact I only finally got the courage to sell my '83 R100CS I'd had for nearly 20 years last fall.

Feel free to email me at motomoron (at) yahoo (dot) com if you've got specific questions.

I'd start with a complete rebuild of both carbs, new fuel lines, and a couple disposible inline filters. Drain the tank, wash it out. Unless they're completely rusty they're usually OK. The petcocks and inline filters will usually catch most of the crap, and being big, dumb twins the idle jet orifices are pretty big compared to say, a modern 600 inline four which clogs with no provocation...
Aug. 25, 2009 2:23 p.m. pinchvalve UltraDork

Nothing wrong with an old Beemer! Pics when its on the road!