I’ve got a small oil leak coming from the seal around the gear shaft, it’s on the vertigo parts list as a lip seal is this just a standard oil seal ? 

It's a standard oil seal, and you can replace it, but it'll just leak again almost immediately. All the early ones did. They made a change to later models to alleviate pressure building in the cases, which is believed to be what causes the leak, but I don't know if it worked or not. 

Mines never done it before, but I have had an issue with oil coming out of the breather pipe in to the airbox, I’ve now got two breathers fitted one on the kick start side where it should be and one on the sprocket side where they where on the earlier bikes and that’s stopped it coming out the breather 

Did you check the primary shaft cover? Sealing area of the cover to crankcase is tiny. 

Yep, that's the shift shaft seal leaking... 

I'm tellin' ya... I replaced mine twice. Never stopped the leak.

Got to give it a try, it will do my head in leaking all the time 

Do these seals just come out with the shaft in place ? 

It’s poorly designed there appears to be very little of the gear selector shaft (smooth sealing area) protruding for the seal lip to slide against. Can the seal go into the recess further, does the shaft have too much float (in and out play). An alternative would be a sleeve resin bonded to the shaft to allow the seal to work on or a shaft with a longer seal land area. I would even consider working the seal housing so that the seal can actually fit further in by a couple of mm. Not had one of these so I could talking nonsense, however from each idea comes another. It does look as though there is insufficient smooth surface for the seal to work on in my opinion.

Edited August 28, 20187 yr by section swept

If it was mine I'd put the seal in the "wrong" way round. Got to be worth a try ?

O ring/rings  including the seal.

1 hour ago, oni nou said:

O ring/rings  including the seal.

Think the o/p is still trying to work out what "wrong  " means ......

Judging by your photo, I would say that that oil seal is the wrong size. The seal has too large of I.D hole for the shaft size, should not have that large of a gap..the outer dust lip of the seal should even be in contact with the shift shaft. Try source a slightly smaller I.D seal, will fix your leak

I've changed the seal for a new SKF one and had run round on it 

for 20 mins or so and it didnt leak and hasnt since so touch wood

the new seal has sorted it