This is just a quick 'heads up' on a couple of things I found in a recent gearbox re-build.
The box was from 'Vincent's' 1991 R65GS - a Monolever bike.
The inside of the box wasn't bad but there was some water in it and some gravel / rust deposits between the output shaft rear bearing and the oil seal.
The output shaft rear bearing was shot whilst the others were mostly OK (output shaft front was a bit worn).
It looks as though water had been getting in down the speedo drive as the drive gear was quite rusty. I cleaned it up on a wire wheel and the rust pitting can be seen here:
The rubber boot on the speedometer cable didn't look too bad, but it will need to be properly sealed when it goes back together.
The water has been in there for a while as its the first time I've seen a rust hole in a gearbox shim
I changed both output shaft bearings plus the input shaft rear bearing. Fortunately the roller bearing at the front of the input shaft was good - though I did replace the sleeve it runs on as a precaution.
That combination was a lot tighter than the new roller bearing I got from Motorworks .
Also, Vincent uses the kickstart a lot. The spring looked fine but I thought I'd change it just to be sure.
It just goes to show what happens to a spring that has been under tension for 21 years . . . Old spring on the left
Its actually relaxed by about 90 degrees .
So if you think your kickstart is getting a bit floppy - you're probably right .
The box had to come out as the Small Pawl Return Spring had broken meaning that the bike was stuck in the last gear selected:
The spring costs £1.43 - but the box has to be stripped to replace it.
I replaced all three selector springs while I was in there.
Before opening the box, I turned it upside down and tried to select the gears and with a bit of fiddling it worked . So - if you are stuck out in the wilds and the pawl spring breaks it really should be possible to select a suitable 'all round' gear such as third by turning the bike on its back. That should get you home (slowly) .
Urban Myth its not .
So, to conclude, If your bike lies out in all weathers make sure that the speedometer cable is properly sealed as water in the box does cause damage .
Bob.
The box was from 'Vincent's' 1991 R65GS - a Monolever bike.
The inside of the box wasn't bad but there was some water in it and some gravel / rust deposits between the output shaft rear bearing and the oil seal.
The output shaft rear bearing was shot whilst the others were mostly OK (output shaft front was a bit worn).
It looks as though water had been getting in down the speedo drive as the drive gear was quite rusty. I cleaned it up on a wire wheel and the rust pitting can be seen here:
The rubber boot on the speedometer cable didn't look too bad, but it will need to be properly sealed when it goes back together.
The water has been in there for a while as its the first time I've seen a rust hole in a gearbox shim
I changed both output shaft bearings plus the input shaft rear bearing. Fortunately the roller bearing at the front of the input shaft was good - though I did replace the sleeve it runs on as a precaution.
That combination was a lot tighter than the new roller bearing I got from Motorworks .
Also, Vincent uses the kickstart a lot. The spring looked fine but I thought I'd change it just to be sure.
It just goes to show what happens to a spring that has been under tension for 21 years . . . Old spring on the left
Its actually relaxed by about 90 degrees .
So if you think your kickstart is getting a bit floppy - you're probably right .
The box had to come out as the Small Pawl Return Spring had broken meaning that the bike was stuck in the last gear selected:
The spring costs £1.43 - but the box has to be stripped to replace it.
I replaced all three selector springs while I was in there.
Before opening the box, I turned it upside down and tried to select the gears and with a bit of fiddling it worked . So - if you are stuck out in the wilds and the pawl spring breaks it really should be possible to select a suitable 'all round' gear such as third by turning the bike on its back. That should get you home (slowly) .
Urban Myth its not .
So, to conclude, If your bike lies out in all weathers make sure that the speedometer cable is properly sealed as water in the box does cause damage .
Bob.