Bmw R80
 

A freind of mine is thinking of buying a 1983 R80rt (I think!) for general tooling around and a bit of two up touring (europe). It has 60,000 miles on it.

I know nothing about BMWs so thought I'd ask on here. What are the R80s like? Good things? Bad things? Things to look out for?

Cheers for any info.

Matt :)

No real reason not to buy it. when I bought mine I chose to get a 1985 monoshock model. The motor is all set up for modern crap fuel and there are no issues with the shaft on that model.

They are OK!
 

mine has 300,000kms on it. Had an engine rebuild at 180,000kms.
They are fairly agricultural in nature, simple to fix and really tough.
Parts are readily available, and fairly cheap.
Now remember that they are 24 years old and although they were top of the line then, they are a wee bit shy of todays bikes performance.
They are somewhat slow to do everything...like stop,accelerate, turn, etc...
As a cheap reliable tourer, that you can overload and abuse they are great.
Check all the regular stuff, rims, brake calipers/pads,cables,etc
some specifics are the transmission oil. check for water! it gets in through the speedo boot. Pull off the rear wheel and check the drive splines on the differential.
They need valve adjustments every 7500kms, and diff. spline lube too.
Lots of Fun in an Old School kind of way.

If it has been used and you found water in the gearbox don't be alarmed but use this to negotiate the price and afterward you should be fine with a fresh oil change and a new speedo boot, about $2 worth or keep it out of the rain.
Water in the box of a standing bike will cause a lot of condensation in the gearbox casing and because most parts are above the oil level you will find a lot of corrosion and the repairs might exceed the bikes value.

Thanks - losing power at speed
 

I bought the R80 in the end (thanks for your help) and have been more than happy with the riding experience!

Quick question on one thing though...

I've had a look at the air filter (which seems new) and the sparks don't have any tell tale problems...any idea why the bike doesn't seem to like motorway grade hills above 60mph (loses power) and shows a general reluctance to go above 75mph? It's much better at lower revs. This is my first old bike (it's 24yrs old, my last was a 13yr old Funduro), so maybe I'm just being over optimistic for a bike of this age. It's good at low revs but seems very sluggish at anything above 3800 revs. Any ideas on what to start looking at?

Any suggestions welcome.

Cheers.

I'm not a Beemer bloke but one thing comes to mind -carb diaphrams - ok that's two things .
Assuming of course that compression is ok and timing is spot on .

When checking the diaphragm replace the main needles and needle jets.
You can't check them as the minutest wear on them will have a major effect.
You will know it is the needles and needle jets if the bike refuses to rev over 4000RPM but has lots of power in the lower revs and still runs evenly balanced. Damaged diaphragms will make the machine run rough and unbalanced as you start to accelerate and you will experience a lack of power through the rev range although it will get gradually worse as the revs pick up. Worn needle jets and main needles will almost have a certain cut of when you get the feeling that the bike refuses to continue accelerating.

The main needle is attached at the bottom of the piston and the needle jet will be held in place by the venturi directly above the main jet. The main needle fit through the needle jet. To get to the needle jet you have to first remove the main jet and venturi and the rest will drop out, or if heavily gunked up, will need a gently push with the tip of a screwdriver.
When buying the needle jet make sure you get the right size. Remove the ones on your carb and you will find the size stamped on the side 2.64 or 2.68 yours will probably be 2.64 If not, it could also be that they have been replaced by the wrong ones before.
Give me your bike model and year and I can check on the electronic parts catalogue what was supposed to be on your bike.

r 80
 

it has the same engine like my r 80 gs. very good boxer machine. Bike is very good itself but a bit outdated. 83 looks a bit older.

Good and tough machine.

Thanks. It sounds exactly as you describe for the "needles and needle jets". The bike runs quite smooth and sounds/feels balanced, but the "bike refusing to continue accelerating" is the noticable problem. The bike is a R80RT first registered in 1983. Not sure if the frame number would help, but here it is just in case 6421552. I haven't bought a service/maintenance book yet for the bike. Can you recommend one? I've used Clymer ones before. Cheers for the help. Much appreciated.

Needle & Needle Jet
 

On your model the needle jet is actually a 2.66, part number 13 11 1 261 702 and the needle part number to go with this jet is 13 11 1 255 840.
I would love to try the Clymer my self but can't get hold of them in South Africa. Have one for the 70's models. More expensive but have heard it is the better one.
I work almost exclusively on the GS models and have all the factory manuals for these models but also have the Haynes manuals. be careful with these as they cover a vast amount of models over a long period of time and it is easy to read info for the wrong model, otherwise useful and better than nothing.

Don't stress about these parts as they are really cheap and you don't need a better manual than this forum.
I suggest you start with one carb and shoot some digital pics as you go along and post them here with all your questions and you will have the carbs sorted in no time. Getting info here as you go along also help others as lots of guys will read this thread.
Actually when you start, rather start a new thread and call it "Rebuilding of R80 Carbs" or something so that others can immediately recognise what the subject matter is.
Good luck and I will be looking out for your questions to give you more advice and even post images if it will help.

Hello Bungle,
Welcome to the club.
I am assuming you are in Bonney Scotland.
Some good parts sources are, motorworks,and Motobins, both in the UK.
I use a Haynes manual and find it better than the clymer.( I have both)
You can get BMW part numbers from the A/S cycles website as they have a section with parts diagrams, but these will be for north American model bikes.
There are lots of Airhead fanatics and mechanics around, so you should be able to find some fairly close to help you out if you have any problems.
Good Luck

Thanks guys. I am indeed in Bonney Jockland. I live in Leith in Edinburgh if that means anything to yoos...

I'll start a new forum soon as gsworkshop suggests so you can see progress. I recently had my tools stolen (and my old bike) so I'll have to wait until the insurance company get me the replacement tools before I start.

To do the carbs you will need only a Philips and flat screw driver and a 8 and 10 spanner.
With these you will be able to remove and completely strip the carbs.

The carbs should be rebuild from time to time, as Gsworkshop says. It’s an easy and nice job but it might be smart to get someone to help you adjust them.
It also increase mileage – for a short while

A few years ago my R80 didn’t run well above 5000 RPM, it ran out of power but was smooth all the way up. This developed over time and carbs and valves was in good shape. I changed the ignition cables and everything worked fine – they are pretty exposed to the elements.

This manual covers R80GS, R100GS and R100R.
It’s almost the same...
http://www.actiontouring.com/bmwtech/manual.pdf

This is a German partlist for R50-100 and has a lot of nice drawings/exploded views (it covers ”all” airheads from 1969)
http://www.actiontouring.com/bmwtech/parts.pdf

This one is also nice:
RealOEM.com Online BMW Parts Catalog

It’s a great bike, congratulations!

Cheers guys. The theiving ****** that stole my toolkit have been caught and they left me one screw driver and the two spanners mentioned. If I'm going to do the rebuild is it worth replacing all the gasket seals while I'm at it? Is there anything else that you would recommend renewing?

Buy a carb overhaul kit, only use those gaskets that need replacing.. grease all paper gaskets first. It is worth removing the carbs and holding them in a vice. DO NOT try to replace the needle jets with the needles installed. Replace the jets first.

I reccomend teh Haynes manual, so far it has been accurate :)

Quick update
 

Well I've finally got round to having a look at one of my carbs. I'll do a proper photo and description for the second carb but I thought I'd share this now as there are some issues that I'd appreciate your opinions on.

On disassembling the carb I found that :

1. The diaphram is burst (and looks like it's been that way for a while).

2. The Idle adjust screw broke off under very little pressure, fracturing the casing (but high up - see pics, I'm not certain it's a fatal thing as it's high enough up to not involve the thread). However this presents a problem now as I can't adjust the idle at all (the screw is well and truely bonded in it's original position).

3. It seems that the jet types are wrong (Needle jet 2.64 instead of 2.66, and Main jet is 148 instead of 150). All of this is according to the descriptions for the 1983 R80RT Clymer manual. My bike is registered in April 1984 so I am assuming it is an 1983 model (the first R80RT).

My big question for you is what to do about the Idle adjust screw. Does anyone know anything about the jet sizes also. How can I tell exactly what year my bike was manufactured?

Thanks.

Also the dust fragments pictured with the main jet above seem to be the remnants of an O-ring. I take it this is a sign that the carb has not been maintained for a long long time or that it got very heated in there at some point? I noticed dark soot on the Air Valve/Slide. Also you can see a slight abrasion on the Air Valve top. Is that something to be concerned about? The Float Bowl also has some build up on it. Someone's obviously scoured around in there too with a screw driver. More pics attached.

How did you postthe pictures ?

I would say that you need that idle screw to work properly, so one technique is to keep spraying it with WD40 or similar and gently "worrying" it until it frees up.

Also, that looks a lot of "dust" for one O-ring. Got to be muck collected over the years surely?

Dave

R80 Carb overhaul.
 

Hi,
Bit of a newbie here myself and no expert but I managed to do a good job on my R80/7 carbs after reading all the tech tips in this forum, asking the questions you are asking and trawling the Internet for cost effective solutions.
I'm not sure if your carb will ever be 100% efficient in view of the physical damage, that is for one of the clued up fellas in this forum to advise you. However, I can tell you where you will find some of your solutions.

First.
Get the engine and frame number, visit this site, BMW Motorcycle Engine & Chassis Numbers , and you will find the exact model and year of manufacture of your bike. If you don't know where the numbers are on the bike, visit there anyway, then, using the links on the same page, you will be able to find out lots of information about the bike.

Second.
Log onto these sites:
BMW Motorcycle Parts // Welcome
Motorworks - BMW Spares - home
BMW Motorcycle Spares - Motobins Ltd - Hints & Tips
By the time you have waded through their parts list, catalogue, exploded diagrams etc. you will have found every part you need. ( and how much it is going to cost) Remember to check the head to carb inlet rubbers and clips, any ingress of air here will upset the running ( one of mine was split causing rough running and impossible down changes because the revs did not 'die down' when the throttle was closed causing me to suspect sticky linkage or cable). Also check the condition and smooth operation of the throttle and choke cables and linkages. Any fouling or 'stickiness' here can mess things up. Again, cables and ancillary fittings (rubbers, grommets etc) are readily available mail order or from ebay.

Third.
If your carb body is damaged beyond repair, fear not, Bing carbs for airheads appear regularily on ebay so it will not cost you a fortune if you want to replace the broken part. I believe that you can get 32mm Carbs and 40mm carbs. I think your R80 will have the 32mm. There are also domed top and flat top versions of this carb. I have the flat top, you may have different, its just a visual check! (The carbs have numbers on them)
There are at least two or three regulars on ebay who break airheads ( that is a sin in itself!) plus the occasional private seller so you should be able to get a reasonable cost replacement if the carb is broken.

Fourth.
Whether you have replaced the damaged carb or not, the next step ( Judging by the condition of the carbs in the pics) is to clean and overhaul both carbs. The basic overhaul kit is around £16 (pair) and this includes all gaskets, O rings and diaphrams ( Which you definitely have to replace). You can easilly get all the other bits you will need depending upon condition. Floats, jets, needles etc. Needless to say, this is best done by removing the carbs from the bike. (A very simple operation). Do the job methodically, use the proper tools, don't bodge and keep it clean.

Fifth.
When the carbs are overhauled and replaced, you will have to set them up approximately at first. I won't describe it ( I may get it wrong) but this operation has been described in one of these forums before. The bike is then started ( hopefully) and given a ten minute warm up. Then the carbs can be balanced. This is best done with the proper vacuum gauges but, again, various cheaper methods are available. It is very important to get the Carbs balanced properly on an Airhead for smooth running and economy ( etc etc). Before I did this, I filled the tank with fresh petrol of the correct grade and fitted a new air filter at the same time. ( Don't forget to clean any in line petrol filters too)
..
An obvious tip here, if you have removed the carbs from a working bike, don't be tempted to do other work or adjustments like points, timing etc until AFTER the carbs are back on and running. If you adjust too many things while the bike is immobile and it does not start again, it is more difficult to isolate the problem.

Hope some of this may be helpful, I'm sure some of the experts on this forum can fill in the fine detail about which screw to twiddle and by how much.
Just don't forget to visit the sites I have mentioned, especially the bm bikes techie site. All the info you will ever need is right here.

Regards
Ian.

It's an option at the bottom of where you add your message (a seperate box). you can only upload 3 images at a time.

Thanks Ian most helpful.

Just a thought but i had a simialar sluggishness above about 60mph on my R80RT which turned out to be petrol tank sealant that had dropped to the bottom of the tank and partially blocked the fuel pipe. A clue was that when going on to reserve it was often difficult to get fuel to flow until removing the petrol pipe from the tap. Hope this might help.
BMW MARTIN

Just returned from a great week's biking in the Outer Hebrides with the R80. I replaced the broken right carb with a second hand one off ebay. I cleaned it but didn't replace the jets, needle, O rings or diaphragm as these looked in good condition. I bought the left hand carb from the same bike also and fitted it to ensure no differences.

The bike now accelerates well through the range (and sits at 85mph on the motorway without any fuss). Previously it had great difficulty getting past 3750rpm. In setting the carbs up I stuck with the recommended mixture settings from the Clymer manual. I adjusted one carb by minus 1/8 of a turn after noticing a sight smoking on the left carb.

The only issue I have now is that between 4000 and 4400rpm it runs a little rough (like it's very slightly out of time on each piston). Above that and below that it's fine. Is this likely to be a needle jet problem? Also can anyone point me to the carb adjustment article I've heard reference to in various places but haven't been able to find. Cheers.