New Atlas owner

I don't own an Atlas, but from what I understand, a commonly done modification is to fit Commando pistons instead of the original dished Atlas ones. This makes the vibration worse than it should be, on a bike notorious for vibrations. Look for real Atlas pistons.

Reply to post. If possible gear up to reduce vibes. If the motor is down get it balanced. Fit a compression plate.check ign timing on BOTH sides. Dont fit a Boyer. Fit a wet sump tap,and a reminder.

I owned three Atlas bikes for many years, including one that survived 5 years of thrashing round every Track Day in my area.

Lots of people bang on about the vibes being a pain and spoiling the fun of running an Atlas. They are not totally wrong but I found that a few simple mods made all my bikes a real pleasure to ride and all of mine were taken on long tours of the UK and Europe and they never left me stranded. ever.

The first thing I went for was to boost power at the bottom and mid range of revs. This was easy and consisted of fitting Commando pistons, electronic Ignition and a 32mm single carb set-up. You do have to remember to reset the ignition from 32* to 28* BTDC to allow for the higher compression but this is easy to do with an Electronic set-up.

The electronic ignition gave easy starting, even firing and was easy to adjust. This boost in power allowed me then to up the gearbox sprocket to 20 teeth resulting in roughly a 70mph cruising speed at just over 4200rpm. Well away from the teeth shattering 5000 passion killing level.

I found that I could now cruise at 70mph and get 65mpg. You won't get anywhere near that with twin carbs.

On two of my bikes, I got the crankshafts re-balanced which also made a huge difference to the engine vibes. Both being filled with oil and dynamically balanced to 72%.

I really like my Atlas. Modifications? I fitted a 2 to 1 inlet manifold and kept the original monobloc carb (so now I have a spare carb - you never know when you might need one). I fitted commando pistons with some reluctance when the original dished one split. Ignition is 25 deg btdc to allow for the higher compression and rather low octane petrol we have to cope with. When we first got it it had a rough main bearing so I cleaned the sludge trap, fitted new standard shells and mains and that was 20 years ago. It starts first or second kick every time and takes me everywhere. Vibration - yes it's there, but not excessive. It settles down to a smooth cruise at 4,200 rpm and really shifts as you hit 5,000. Oh, the other modification - electric handlebar grips. Wonderful. Enjoy your bike. Gordon.

The reason that the Norton Atlas twins vibrated when they were built at Plumstead was all because of piece work. I was told by a well know dealer who went with the Berliner brothers to Plumstead in 1966 and he watched the guy who balanced the crankshafts. One he did perfectly, and then the other nines as the first one. He then balancedone perfectly then the other nine as this one. So you can now see day in day only one in ten was balanced correctly, hence the Atlas has the really bad reputation for vibration, and it was all or mostly down to the factory. I have about ten Atlas engined bikes, and they all vibrate to some extent, but they have all been rebalanced so they are not that bad. When left standing park them on compression, as this blocks of the big end oil hole,so the oil does not leak through the big endhole so quickly.

This has takenfour times to post this and it keeps getting lost, so it is now becoming a joke if you put a long or even a short post on the web site. It is about time it was fixed. I saved it on a word document and was suggested by some one berfore but it is still a pain.

Previously wrote:

Reply to post. If possible gear up to reduce vibes. If the motor is down get it balanced. Fit a compression plate.check ign timing on BOTH sides. Dont fit a Boyer. Fit a wet sump tap,and a reminder.

Hello Fitting a wet sump tap Its BAD advise Do Not fit any thing in the inlet side too the oil pump , Fitting taps or wet sumping valves Only Masks the real problem Of a worn Oil Pump and warn presser release valve , Your AJD

Norvil do a conversion to the timing cover as per the Mk3 Commando models. Norton finally admitted via this modification that they had an oil drain problem via the oil pump. I have had oil pumps over hauled and they still drain down into the sump.Anon oil return valve was fitted by Velocette as the Velos also had a gear type oil pump. Oddly my T100R does not leak its oil via the oil pump, but that is a plunger one that i fitted from Morgo.

Previously wrote:

Norvil do a conversion to the timing cover as per the Mk3 Commando models. Norton finally admitted via this modification that they had an oil drain problem via the oil pump. I have had oil pumps over hauled and they still drain down into the sump.Anon oil return valve was fitted by Velocette as the Velos also had a gear type oil pump. Oddly my T100R does not leak its oil via the oil pump, but that is a plunger one that i fitted from Morgo.

Hello Yes oil does drain to the sump on any dry sump engine but its ONLY A Dry Sump engine When its running, And a paint of oil in the sump will do no harm to your Engine Infact it helps The engine to lubricate its self There are Only two part of a Norton Engine Thats Under Pressure from the Oil Pump One Is the Journals IE bottom end ,Number two is the return pressure to the rocker arms via the rocker spindles ,and the like, Every thing else in The Norton Engine Is Splash Feed , And it takes the oil pump 50seconds to build up the its pressure , So your Taps and Ani-Drain valves are Doing your Engine NO favorers This All UP to you If you want your engine to last then Do Not Alter The oiling system on your machine ,Burt Hopwood And Doug Hele And Jack E Moore knew what they where doing when they designed these engines in the first place , Built To last, Thats why there over 50 years old and still running Yours Anna J Dixon

Again, Anna is completely correct in saying that you shouldn't need any form of anti-drain oil valve as the term "Dry sump" only applies to a running engine. Ifoil drainingis excessive then the pump is likely to be at fault so needs servicing. No oil in the sump at startup means no splash lubrication - which is definitely a BAD thing with Norton engines! Follow Gordon's principle.

The Norton pump can have somelimited servicing in your workshop - like my favourite Jaguar XK engine pump which is naturally quite a bit bigger and is an eccentric rotor type, but the principle is the same. Face down the brass cover plate on a piece of 1/4" plate glass using valve grinding paste or 1000/1200 grade wet and dry, used wet. The pump plate should be completely smooth with no indentations at all. Polish it afterward so you can see how the gears run against it but always test this with all parts oiled. In the unlikely event that the gears have insufficient clearance you can do the same with them. You can put a straight edge across the body and check the gear clearance with a feeler guage (plate removed). If it's too great you can face down the body in the same way as before. It's actually a bit easier on the larger Jaguar pump, oddly enough! Obviously none of this can address gear wear. That will be the result of using detergent oil in a bike with no fine oil filter!

Cheers, Lionel

I have been an Atlas fan since I bought my first one in 1964. I am presently running with an 850 engine rebalanced and using a decompression plate. This gives easier starting and less vibration. This is a daily runner and does not have a wet sumping problem. Original ignition and rebuilt concentrics, high output alternator for better lighting. I love those featherbed frames.