Would R80 speedo work on R65?

[Mucci]

The speedo on my '83 R65 blew up. I'm about to go on a trip and it'd be nice to have a working speedo. I've got one from an '85 R80RT. I realize it reads to 140mph but I was wondering if the ratio is the same as the R65's so that I could pop it in before I leave.

[georgesgiralt]

Hello !
At the bottom of the front face there is a Wxxx number.
It give the number of turns you need to advance one mile on the odo.
If the two number match, bingo, you've got it. if not, sorry it won't work (speed won't be accurate and odo false).
As the gearboxes are all the same, ration wise, the difference lies in the rear. you have to check that the R65 has the same rear drive as the R80 which she normally has not.
I hope I'm not wrong on this but you can check the numbers for yourself ;-)

[jp9094]

Monsieur George is correct. However the discrepancy may not be that great. My  original speedo quit shortly after I acquired the bike. The replacement I found had a different Wxxx number. I tested it and it is off exactly 5 miles per hour (indicates faster).  As a "field expedient" it might save your trip.  I tested mine on one of the many  Radar speed stations found in various locations around New York City.

[Mucci]

Great, thanks guys. I'll have a look.

[Barry]

Speedo ratios in both miles and km that match with a particular final drive.

[Mucci]

R65 is W 1318 and R80 is W 1244 :/

Wonder how off that would be. Better than nothing if it's only 5mph or so.

[k_enn]

I believe that somewhere (Snowbum's site?) I saw a table that relates the tachometer reading to speed for the various gears.  Since the real speed issue is usually on highways, it top gear, you could locate that number and gauge your speed by your tach reading.  I did that for a while until I got my speedo repaired. 

Another alternative is available if you have a portable GPS.  Most of those are capable of tracking speed, and when I have mine mounted on the bike, I often check speed off of that. 

k_enn

[Barry]

R65 is W 1318 and R80 is W 1244 :/

Wonder how off that would be. Better than nothing if it's only 5mph or so.

It's only an error of 5.6 %

Bear in mind though that the odometer and trip meter would also be 5.6 %  in error

[Tony Smith]

Any number of GPS based speedo apps for mobile phones. My wife and I used one in the Kombi when the 40 year old cable broke 800km from home.

Bicycle computers such as the low end Magellan range can be found on special for well under even 100 Australia Pacific Pesos.

Another alternative is to buy a cheap (around US $70) 85mm (or bigger) GPS speedo and then pay an instrument fitter to use it to replace the "gubbins" in  the original speedo. I have gone this route, in that I've bought the GPS speedo and a dead R65 speedo still yet to  send it all to an instrument fitter. In the US of course you have the option (at a price) for sending your dead R65 speedo to speedhut.com and have them fit GPS internals to it.

Of course the last alternative is to simply repair the original, I posted a source of gears a few weeks ago, failing that a visit to a toy shop will secure a number of the wrong sized gears made of suitable material and then armed with fine rat tailed files you can make your own.

[k_enn]

Is WireSpokes still around (on this forum, or BMWMOA) and does he still repair speedos?  He did mine a few years ago (but be warned, it took a while to get the job done). 

[Barry]

I've see him more often on ADVrider.

[orforester]

Wirespokes rebuilt mine about two months ago, I highly recommend him, real quality work at a fair price.