Bmw R80

[Matt Cartney]

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

[oldbmw]

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.

[Cameron]

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.

[gsworkshop]

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.

[bungle]

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.

[Dodger]

Originally Posted by bungle

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 .

[gsworkshop]

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.

[Samy]

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.

[bungle]

Originally Posted by gsworkshop

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.

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.

[gsworkshop]

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.

[gsworkshop]

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.

[Cameron]

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

[bungle]

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.

[gsworkshop]

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.

[AliBaba]

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.