help: broken speedo-will i put it in a garage at last!!

[batman]

bah, the bike is finally runnin fine after my ring replacement, fixin overheatin probs and (thanx to keith) powervalve cleanin
now the speedo is gone-i havent looked at it yet, but dont actually know what i am lookin at! what ususally causes speedo failure?
should i go for another rip it apart and see what happens?
or should i send it in for the first check by a garage it will have had?!!
thanx all

[Doddmaster]

take out the end of the cable that goes to the speedo. roll the bike slightly and see if the wire inside the cable is turning. If it isn't, then the problem is either a broken speedo cable (which happened to me) or your speedo drive in the wheel is bust

[Bob]

If the front wheel was out of the forks during the engine rebuild it could be the speedo drive is not engaged properly. This needs checking as if not correctly fitted if is possible to damage the wheel bearing (not difficult or expensive if you have).

First check is as Dodd says disconnect the cable from the back of the speedo (unscrew nurled nut it should only be finger tight). Spin the front wheel if the inner is turning it is probably ok, if not or looks jerky disconnect from the wheel end (a single cross headed pin) if the cable is broken it should now be fairly obvious as the inner will either be in two bits or one end will be damaged.

The speedo end should have a definite square shape to it, the wheel end has a flat screw driver shape to it. If the cable appears ok then spin the front wheel and look in the speedo drive, a slotted drive shaft should be seen turning if it is jerky or not turning the problem is in the speedo drive.

Take out the front wheel the speedo drive gear box will drop of the side of the wheel examine it there should be two slots on the inside that mate up with lugs on a ring sitting in the wheel hub. The lugs and the slots should mate cleanly, no part of the assembly should come into contact with the inner race of the wheel bearing or the dust shield in the bearing, the drive ring should only contact the wheel hub and the outer race of the bearing. Any problems here and I would look at replacing the front wheel bearings and if the drive ring is damaged you may need to replace it, but if the lugs on the drive ring are damaged / bent back towards the wheel bearing with care they can usualy be bent back into place but if they are not there or break off then you will need to look for a new drive ring.

Sorry for the long winded speal but I have seen a problem reported speedo packed up after fork seals where replaced when I checked the cable and drive found the gear box not working took the wheel out and had a nice little cascade of ball bearings fall out. The speedo gearbox had just been placed over the hub and the lugs not located in the slots, when the wheel was tightend back in the forks the gearbox assembly pushed the drive lugs back into the bearing were they started ripping the dust shield and stripping balls out of the bearing. Up to this point there was no apparant problem with the front wheel, it was scary because the bike had just come back from a 120 mile run and the speedo did not work through out the ride. A wheel bearing collapse at 80mph does not bear thinking about.

[Robby]

its nice to know RS125s are reliable and dependable. out of interest, have you yet had one week on it with no trouble?

[bikerboy1]

YUP no troblem with mine!!!!! my mates has had his for a year and a bit and the other thing that went wrong was someone at his work reversed into it!!! and knock it over!!! but i depends if you looks after it or not

[batman]

ive had a year-most of the problems that came up were after we did the rings
they were that the coolant was too thick we put in, and that the powervalve was stuck
the bike has done 10,000km now and has never been in a garage, and it is runnin perfectly
i know 2 nsr's with broken speedos too, its a commom occurence
thanx for the help all, just dont wanna have to send it in until necessary!

[Kickstart]

Hi

Aprilia seemed to have a bad batch of speedo drives recently (strange as the old ones were fine), and my guess is this is the problem you have

All the best

Keith

[batman]

i think its the drive-at the mo im not too worried because the mileage isnt goin up!! still 9600, could do wonders for resale value!