Tacho drive gear

It seems that there are 3 versions of the tacho drive gear.
1 - Plain shaft, no o-ring groove or oil spiral
2. -Shaft with both o-ring and oil spiral.
3 - Shaft with o-ring

Can anyone tell me if the above sequence is correct date-wise (i.e. the o-ring only version is the latest one?), and on which models they were used?

Thanks,
Steve in Denmark, trying to de-oil leak his Commando

SteveBorland said:

1 - Plain shaft, no o-ring groove or oil spiral

Click to expand...

06-1089,
1969(20M3S) - ?/'73.
http://www.nsamotorcycles.co.uk/06-1089 ... 5178-p.asp

SteveBorland said:

2. -Shaft with both o-ring and oil spiral.

Click to expand...

No information.

SteveBorland said:

3 - Shaft with o-ring

Click to expand...

06-5201,
?/'73 (Mk2/2A supplement from 307311)- on.
http://www.nsamotorcycles.co.uk/06-5201 ... 4876-p.asp

Thanks LAB.
My 850 MkIIa has #2 and was pumping oil out of the cable junction, even after installing the oil seal mod. I did a temp bush fix by using some blue Hylomar in the oil spiral, which seems to have helped rather a lot. I've now acquired #1, and will be trying this with the oil seal instead.

/Steve.

You have to use the unscrolled shaft with the oil seal mod. The scroll only moves oil past the seal. 2 Nortons changed to and never a drop from that area. Plus you need the breather valve exiting the engine if you really want to be oil tight.

I've used the Motormite one discussed elsewhere. It fits in the oil breather line, replacing the reduction fitting on the way up to the tank, out of view.

Cheap and works like a champ



P/N 80190, if I remember right.

Yes it's made of real genuine modern plastic and works great. 4 years on mine. Six bucks so pop the champagne. :!: