oil consumption Norton Dominator 650 ss

My 99 ( in good condition) uses about the same as your commando, but my engine breather goes into the oil tank which saves oil on startup. Without this it would use double.A lot depends on useage. Lots of shortish rides will produce condensation in the oil and the level won't drop much with my breather arrangement,A long fast trip will burn off the water and I will notice a big drop. I think this is normal for these old clunkers which run relatively big clearances with rudimentry oil seals and burn oil. I remember doing decokes (in the Distant past) ,who does one on a modern machine?.There are lots of reasons for excess oil consumption on a 650SS but Tomas has asked the RIGHT question ,what is normal?.

Not Dominator but Edgar Franks suggests 200 - 250 miles per pint for the singles......

Previously Tomas Tesar wrote:

Hello, can anybody help what is standart oil conumption on this bike? on valve guides there are seals. new reborn cylinders and new pistons, motor has 2000km from General repair . on my commando i have 0.6l per 1000km but domi takes much more.

Thanks.

Tomas Tesar

Hello there is no inlet valve oil seals On a 650 but you may have your return oil-way blocked at the bottom elbow this is common on most nortons the oilway runs from and base of the valve seat collars in let side , and if these are not in the right place they can block the oil way and the 650 were fitted with in let rocker cover breather banjo has from the First 650 Manxman november 7th 1960 my one is a december 7th 1960 Norton Manxman 650 these had the five peace oil rings with the expander ring at the back of the five oil rings, it was may 1961 when the twin flex oil rings were fitted to the 650s and oil consumption should be about the same as your commando, Ps the timing cover oil seals have to be in good condition if not these give you problems yours anna j

Two years ago I had my 650 Manxman engine rebored to +20 thou. The pistons used were good second hand 99 type with the skirts cut away to match the crankshaft central flywheel. At the time of the rebore I asked the engineer to hone the bore so that I could use the bike as soon as possible for fast riding. This turned out to be a big mistake as the honing was so fine the rings did not bed in properly for nearly 3000 miles. The consequence of this being massive oil consumption for the first 1000 miles and then 1.5L for the next 1000. It was only late in this year that I no longer had to carry spare oil with me on rides over 400 miles. The engine now swallows about 500ml every 500 miles.

Hi Tomas,

I'm currently facing the same issue with my 65 650ss. Mine smokes from the right exhaust on tick over but stops under acceleration. The engine gets through a lot of oil I'm told this is likely a cylinder head/valve guide issue, not sure why?

Previously Tomas Tesar wrote:

Previously paul_dudill wrote:

Hi Tomas,

I'm currently facing the same issue with my 65 650ss. Mine smokes from the right exhaust on tick over but stops under acceleration. The engine gets through a lot of oil I'm told this is likely a cylinder head/valve guide issue, not sure why?

Paul and your engine is rebuild ?

Hello the other thing I found with the 650 is the ring end Gap compression rings should be 8 thou to 10 thou no more then this, oil rings 8 thou, max , and with twin flex rings there easy to get a cracked oil ring if one is cracked it will smoke on that side , you must take great care in fitting the pistons into the barrels have a friend in to help or make to barrel fork out of ply wood this wooden fork fits around the connecting rods to stop the barrel dropping to far give you a chance to fit the rings into the barrel even if you are using piston clamps and you need your base gasket in first be fore you start fitting the barrels I use Stag wellseal and apply with a small artists paint brush sparingly and let dry, a bit , yours anna j

Hi Tomas,

yes re sleeved and bored back to new standard pistons. I've now got the head off and it appears a poor fitting right inlet valve is the culprit. They seemed fine when the engine was rebuilt but clearly this one isn't, no idea why. I'm fitting +0.05 guides and new valves all round and hopefully it will be sorted. Thanks to Anna i have checked the oil way is clear to drain. Good luck. Paul.

1 litre of oil every 100 km, wow! Must have been making more smoke than HMS Hood at 30 knots! Lucky for the planet that you found the cause.