Hi I am not sure if the question is well formulated in English but the issue is as follows: Have a speedo R80G/S W=773 Needle is crazy, odo went to zero, nothing seems to work. Can't find direct swap. But was offered a W=747 What do I need to change and were to make this speedo work accurately Question # If I buy a W=773 speedo from another bike can I use the guts of that one to repair mine and if so what chance I hae of success? The issue with the other speedos is the location of the trip meter, unsuitable for the R80G/S pod. Yes Yes I know I should buy a vapor but I got a Sigma as a spare and well I am stubborn and old bikes are to be kept original and functional so I want to fix this. Besides I do not like to have to concentrate on small screens prefer a needle for easy reading. Thanks for clarifying this and or suggesting another alternative, but I want to fix this speedo!
From the numbers you listed, I'm guessing those are metric speedos? And I'm guessing that the one you've been offered is a taller ratio. Perhaps it's the one that came with the R80ST for the optional taller final drive. If you install that one, you'll probably read close to right on or maybe lower than actual speed, but the odometer will show less than actual distance travelled. The bezel will need to be removed to replace the speedo, so why not take a look at it first? A lot of times the problem is water entering through the reset button and rusting the mechanism. Perhaps the rust can be cleaned up, the mechanism lubed, and it'll work again. Worth a try!
This is nothing new to us Airheads.... I would open the old set up and see what is going on. A lot of pieces are plastic and after some time give up or jump out of place. It may be a simple fix. You will not know until you open it up. Any Airhead speedo will work, but you will have to calculate the differences based on your stock set up (speedo and rear drive) and what you are replacing it with... You may be able to get a used speedo and and harvest the parts and fix yours...
I hadn't compared the two - the G/S style and the regular airhead style - but think they're way different and not interchangeable. Usually I notice things like that. It is possible to mount the regular airhead gauges on the G/S (seen it done) so know it can work - and it looked pretty good. Don't know how they'll survive on a G/S though. But you mentioned wanting to keep the bike stock, so that option is out.
This information was valuable to me and helped me fix my odometer: http://www.airheads.org/content/view/160/98/
The 80GS and 80G/S Speedos - mono and para - are the same R80GS & R80G/S MPH/KPH = W1244 3.36 (RATIO 37.11 SPEEDO 1.244) The older Speedeos would have been expressed this as 1.244 rather than 1244 W773 = R80G/S and R80ST KPH only W means 'Wegsteckenzahl' ('travel-distance-index-number'), which equals the number of rotations for 1Km and/or 1mile (a mile would need more W's) travel on the speedo - this is both for recorded mileage and speed to answer your question - the speedo matches the rear drive ratio Hope this helps
hey thanks to all for the amswers but I am none the wiser. Yes the speedo is Km/h But not all the speedos in Km/h are the same. I have a 773, I can see one which looks the same and is also in Km/h but is a 747 I cannot play with the broken speedo. I am about 10000 miles from the bike! I cannot send it to a repair shop and wont have the time to do that. I wonder if it is worth to buy the guts of another speedo or the 747, or it is just a lame idea and a waste of time and money. Or if I can buy a R80 speedo and use the guts. Thanks
Simply put If you fit the 747 - and if it fits, it will be 3.5% different, (less accurate), than the 773. i.e. the rear wheel on a standard R80G/S turns 773 times per kilometer and that is why it needs a W773. The normal R80 rear wheel turns 747 times per kilometer Don't ask me why they are different The correct Speedo for a standard R80G/S is W773 or W1244 You should be able to pick one up for under US$100 - used BM Speedos are not particularly accurate - if you want complete accuracy, use something else
would very much appreciate your expert advice. My 81 R80 has of course Motometer W1244. These are impossible to get new any more. But I have found for a good price a brand new W1202... claimed to be off a BMW R80 GS ( not G/S) so I preseume a paralever. When I lkook up the part number on a BMW fiche it says in the notes "I=3,20 MPH" . The part is 62121244647 My gut tells me this is a Para R 80 speedo, and will wrok perfectly on my 37/11 ratio stock 81 R 80 G/S. Or am I all screwed up? Here is the link http://www.realoem.com/bmw/showparts.do?model=0471&mospid=51686&btnr=62_0213&hg=62&fg=05&hl=4 I am sure you know them..a very good factory fiche. Hoping to hear soon as this speedo will not be around long!
If you are talking about the speedo from the guy in France on Ebay I bought one for my G/S. Yes it worked, but at an indicated 70, I was doing about 62. Kind of annoying, but I just did the conversion and liked the odometer for fuel fill ups.
Most of that difference is due to the 'optimism' of the original speedo. The difference between a W1202 and W1244 is only about 3.5% or a bit over 2mph at 62.
My '81 G/S has its original W773, odo is not working. Found (and bought) a W735. Hope the "new reading" will be not too far from real speed. Does anybody know a "serious" speedo workshop somewhere in Europe? Found some in USA, but shipping is expensive and the "honest italian customs" will make me pay import taxes to get back MY speedo when fixed.
I've never done this but given the speedo ratio is the number of cable revolutions per Km traveled then answer can only be be that there has to be different gearing inside a W747 and a W773 speedo. Logically if the gearing wasn't different the odo meters wouldn't record the correct distance. If I had to guess I'd say the change would be in the input gears otherwise there would have to be a separate corrections for both the speedo and the ODO. I'd take both of them apart to try and spot the difference in the gears.
Reviving an old thread. I have a cafe racer that is a parts bin special, but all with BMW parts from other models. One thing I've noticed is that my speedo (which is the original W-691 speedo) seems to read a bit fast. When doing an indicated 120km/h the GPS speed is in the region of around 105km/h - it thus overreads by around 15km/h. Not sure if this is normal. I'm not running the original 33/11 final drive anymore, instead I have a 31/11 final drive with a 160/60x17 sized rear wheel. The tyre/rim combination is smaller than the original 4.00x18 wheel, but with the changed ratio, the overall effect I've calculated to be the same (within 2km/h), so I'm expecting the speedo to not be much affected by the change. If I do intend "recalibrating" the speedo to read more accurately, has anyone figured out if there are different gearing in the speedos related to the W-numbers?
gorma - I've not heard of a 31/11 FD - guessing it's a 32/11? It gets confusing, but I'm thinking the original diameter wheel would have gotten the speed reading about right, and the smaller one negated the switch to a taller final drive. From the factory, the speedometers read high, but the odometers are pretty close. Have you calculated how many revolutions the wheel turns in one kilometer? What's the circumference of the tire? How does the distance compare between the GPS and the odometer? Yes, the W number indicates a particular series of six gears driving the odometer. That gearing converts speedo cable revolutions into the mileage reading - in your case, 691 revolutions/kilometer. It can be changed and adjusted. The speedo is actually two gauges in one - speedo and odometer. They're two individual and separate gauges joined at the input shaft. If all you're interested in is the speed reading, that can be adjusted without correcting the odometer, if it is off - which it might not be with the wheel/tire change.
Go to snobums site. He has the corresponding W for each final drive ratio. Generally swapping speedo is the easiest solution. Edit: Should have just waited for wirespokes response ;-) I'll defer to him....
The final drive is a 31/11 Paralever unit from a R1100RS if I recall correctly. It might well be that the speedo reads correct albeit a bit on the optimistic side - would however be great to adjust it if at all possible, but need to figure out how it works. Here’s the front face showing the W number There are two white gears turning the mechanism containing the odo via direct gears and the speedo via the magnet. On this one (a spare unit I have) the white gears have 12 teeth each…I suspect it could be these that differ between the various W numbers? Or not? Below is the magnet pickup on the speedo. From my gearing/wheel size calculations, I’m happy that the odo should be very close to accurate (if the original setup was accurate). The speedo however is the component I’d like to get to read about 10km/h slower which should then over read by a more acceptable 3-5km/h. Any idea how to do this? Perhaps remove the needle and remount in a different position?
Kiwiabbo, that is certainly one way to solve the problem, and I would imagine the calibration can be set to get the speed fairly accurate. I have considered alternatives, but more along the lines of something that would fit the original housing…quite like to look of it. But then again I may also fit an S fairing in future and that would hide the instrument cluster in any case.