Double Speed Oil Pumps :

In another thread Bernhart wrote:

".....double speed oil pump were fitted from 1966 on, it was a common mod to fit these oil pump gears to earlier bikes."

This is the second or third time I have seen in print that double speed pumps were not original equipment on heavy Norton twins until mid to late Atlas production run. I have a Norton published service manual ( no date of publication) that so states double speed pumps were "fitted to later models".

Here is my mystery: I bought my Atlas new. It is titled '63, but according to serial number, was built late '62. It has a double speed oil pump...as original equipment. It was not likely a dealer installed mod.

Bernhart also points out the oil gallery diameter was increased in later years. In my case, I find the diameter is reduced compared to an early Cdo pump. Thus in summary, my '63 has early oil gallery geometry and late oil pump.

I am more than curious. There are other anamolies about the bike, but they are fodder for another thread.

Any explanations?

Slick

learn something every day, I was always of the belief that the 6 start gears were only fitted to Commando engines.

Naaa, Nortons had a lot of trouble with that left side piston seizing.
They added an oil squirt hole to the conrods, and made the pump spin faster.
Somewhere along the way, they also added pressure oiling to the head.

It was later found that the piston design/manufacture was the 'oiling problem'
and the oil squirt holes were a solution looking for a problem.

Quite how you would tell if an oil pump was fitted originally must be quite a skill.
Don't any owners think a Dealer can make a perfect job of retrofitting stuff.
Or an owner with a good screwdriver, come to that.. ??

Rohan said:

Quite how you would tell if an oil pump was fitted originally must be quite a skill.
Don't any owners think a Dealer can make a perfect job of retrofitting stuff.
Or an owner with a good screwdriver, come to that.. ??

Click to expand...

Now why would a one man dealership, with one mechanic (part timer at that) take a Norton out of the crate and install a 6 start pump and drive gear? I doubt that Buzzy, the dealership owner, would know a 6 start drive gear if it fell into his health food blender. I am the original owner, and I know the provenance of the bike.

Mystery: How does a Norton get a part several years before its time?

Slick

Didn't the factory issue bulletin(s) about fitting the 'upgraded' oil etc pump ?

The pump would have been out, several times at least, over the decades - to fix wet sumping ??
The same pump always went back in ?

You still have a scavenge-fed oil system to the head ?

Most likely they had developed the 6 start gears much earlier for racing or endurance purposes.

So the parts were probably available. Doesn't answer why they were fitted to your bike, or by whom, but as you say the factory (or importer!) would seem to be the most likely candidate when en-route to you, not the dealer.

Now, if the factory or importer thought the bike was going to be used for some specific purpose, like road testing or production racing?

Just idle (and probably pointless ) speculation, but I bought a new bike in '75 that was one of the first batch of its type in the UK.....It was identified by the dealer as significantly faster than other bikes of the same model they received, and faster than their own production racer...out of the crate...you ask them how they found that out!. The dealer speculated that the bike was intended to end up with the road testers. Who knows?

I just continued my own road test programme after fitting some Dunlops

My information came from the Green cover Norton workshop manual, covering all Atlas models, purchased cir 1970.
My 1965 Atlas had originally 3 start worm oil pump gears.
Your Six start worm was a mod available from people like Dunstall, Gus Kuhn and other Norton dealers.
Statside bikes were often 1 year ahead of the ones available in the UK,
i.e. the 650ss and Atlas to name but two, were not available in the UK until 1 year after they were in the dealers showroom in the US

SteveA said:

Most likely they had developed the 6 start gears much earlier for racing or endurance purposes.

So the parts were probably available. Doesn't answer why they were fitted to your bike, or by whom, but as you say the factory (or importer!) would seem to be the most likely candidate when en-route to you, not the dealer.

Now, if the factory or importer thought the bike was going to be used for some specific purpose, like road testing or production racing?

Just idle (and probably pointless ) speculation, but I bought a new bike in '75 that was one of the first batch of its type in the UK.....It was identified by the dealer as significantly faster than other bikes of the same model they received, and faster than their own production racer...out of the crate...you ask them how they found that out!. The dealer speculated that the bike was intended to end up with the road testers. Who knows?

I just continued my own road test programme after fitting some Dunlops

Click to expand...

I have always felt SteveA's explanation was the most plausible one. That is, factory or importer had something in mind when it was built. Perhaps it was a "Beta" model to road test the 6 start pump years before putting it into production. But if that were the case, I think there would have been some follow up questionnaire, but it is easy to imagine how such follow up could fall thru the cracks, particularly coming from a small dealership.

In another post, regarding Atlas performance, I proposed the bike might be that sort of "one off", and took a lot of flack. As I said, this bike has more than one anamoly.

As far as the dealer responding to a Norton service bulletin, that is wildly implausible. If such an upgrade were so important to the factory, why did it take so long to become standard production?

Slick

As a postscript to my earlier reply, I drilled the bigger oil holes to the oil pump in the crankcase while the engine was stripped, with the benefit of hindsight I wish I hadn’t bothered as all this caused the oil to wet sump quicker than ever before, fitting the Commando rocker feed pipe and longer bolt would be all that I would do with the 6 start oil pump gear.

Longer bolt ? Please explain.

KHK said:

Longer bolt ? Please explain.

Click to expand...

I was thinking for the Commando rocker feed, you might not need it.

Bernhard said:

KHK said:

Longer bolt ? Please explain.

Click to expand...

I was thinking for the Commando rocker feed, you might not need it.

Click to expand...

Will this allow alternative means of lubing rockers? That is eliminate bypass off return oil line?

Slick

The pressure fed rockers and oil squirt holes in the rods were the reason the extra oil capacity was introduced.

If you have extra oil capacity, and its not used, all that happens is the oil pressure relief valve just dumps it all...