Dommie breather oil leak

I have piped the breather into a tower on my oil tank and installed a larger exit breather from the tank. With the regular oil changes and the generally hot running air cooled motor condensation is not a problem andthis has been a vast improvement on the orriginal set up.I used 3/8th copper end feed fittings used in gas installations,and plumbers solder.

I did much the same except that I fitted an oil tank from an Atlas - that comes ready equipped with an oil separator tower and saved the effort of adding breathers to the original oil tank. Lazy, huh?

Dear Mr Osborne,

I've had similar issues with my Inter and Easy2 but the best solution is simply to fix a duck's bill breather, part no 140167 from Hitchcock's Motorcycles Ltd, Solihull, Tel No 01564 783192 for about £4. They are approx 8" long so will need to be shortened with a stanley knife and then simply attached with a couple of tie-wraps because the bore is slightly bigger than the outside diameter of the Norton breather pipe. The law of unintended consequences works here: because they are so efficient you have occasionally to oil the chain with an oil can.

Regards,

Peter Bolton

I think what Jon is describing is a normal consequence of wetsumping, particularly if it only occurs after the bike has been unused for a while. As the pressure builds up, the oil in the sump has to go somewhere - usually out of the breather pipe. Personally I wouldn't worry about it. My dommi does the same thing after being laid up for a few weeks, I find the easiest solution is to drain the excess oil from the sump and tip it back in to the tank before starting.

Compared to the earlier Dominator oil tank, the later one (650, Atlas with high pressure rocker oil feed) has a large inlet to which the breather pipe (3/8" diameter) is connected and a breather/overflow pipe which is connected to the top of the chainguard. Not quite so good for keeping the chain oiled as the original breather pointing at the gearbox sprocket but much better for keeping the garage floor clean. Gordon.

Mine is a DL so it has an extended filler pipeto under the seat. Easy to drill holes for the 3/8th copper pipe for in and out after i sawed off the old small bore breather pipe from the neck. The rear chain now gets little oil but is better off with modern chain spray and a modified (improved!) fully enclosed chain case.I modify everything ,and if its not broke i'll fix it anyway.

Sorry if this is stating the obvious...but when you had the engine apart did you check out the crankcase breather assembly at end of camshaft ?

Just a thought

regards John

Previously john_baker2 wrote:

Sorry if this is stating the obvious...but when you had the engine apart did you check out the crankcase breather assembly at end of camshaft ?

Just a thought

regards John

well have got the timed breather spring in the right way, as it goes in between the camshaft and the breather end plate to keep the breather end plate running against the timed breather plate in the cam tunnel end, and this part of the oiling system on all Norton twin is down too splash feed, from oil been flung of the center fly wheel when your engine is running ,and I keep posting the same thing trying to get this into the owns heads that the biggest part of the oil system is down to splash feed or atmospheric from the engine breathing , My 650 Norton manxman as a Breather banjo fitting from the center of stud fitting on the top of the inlet rocker cover, the pipe from this goes the a T fitting to the pipe that oils the chain at the top of the chain guard, the breather from the crankcases goes to too my oil tank via a ball valve fitting in line but really I feel there sound be a small breather tank for its , in stead of breathing in to the oil tank via the tower, I am goning too experiment with this one and see witch works the best, sometimes there no easy answers so you got to think things thorough first, and Were do you get oil pump gears from , as I look at the the supplier and no one sells a set of replacement oil pump gears , some of these oil pumps in use in our Nortons twins are well over 50 year old and this is were most of this wet sumping lies from near worn oil pumps, but the body of the oil pump will be ok its just the gears that do the work, that need replacing, and the oil seal so it one to look in more depth . yours anna j