Oil spray over rear wheel of 47 ES2

Norton, in their wisdom, designed the crankcase breather to vent over the gearbox sprocket. This was a geat idea, no need to oil the rear chain. Unfortunately, depending on oil level, and how hard the bike was driven, it also lubricated the rear wheel!! A simple solution is to run a plastic tube, from the breather pipe to the rear mudguard, and let it blow out behind the bike. Slightly more ecologically friendly, is to run it into a small can. There are several more technical methods, but, in any case, you will have to remember to lubricate the chain manually.

Hi.

John's pretty much nailed it. The only thing I can add is thatthe sleeve (4th)gear has no oil seal on the upright gear box which adds to the problem. Fitting a bearing with a rubber 'shield' helps. There is also a second engine breather that runs through the centre of the crank drive shaft exiting at 6 'o' clock behind the engine sprocket end of the primary chaincase. Although little, if any, oil is blown out through the breather per se,there is nothing to stop oil from the mains making its way out along the shaft and out the breatherhole in the crankcase- this is why the primary chaincase often appears to leak yet never runs out of oil.

If there is a lot of oil coming out of the breather then, provided the rest of the motor is in good nick, it's worth checking the pump for wear on the scavenge side -after 65 years it's probablysucked the remains of at leasta couple of big ends through it by now!!!

Regards,

Ian.