Atlas or Not-las?

The frame number points towards a 1966 Model 88SS.

I might be wrong but generally the frame is stamped with the Model indentifier.....which for a 500c Norton would be 122 and not 88.

On the frame plate......14 would be used for a 600,  18 for a 650 and 20 for a 750 engine.

The 500cc range used 12,  then 122 and finally 88SS on the left engine cases.

Your frame is a post-1963 version of the Slimline which was used by the 88SS, 650SS and Atlas engines. These frames have the welded-in top gearbox cross-bar.

The engine seems to have a barrel from a 99 Model.  That's fine so long as if the rest is 650cc it will have had the slots added to the barrel for the heavier con-rods.  I have never seen 88 stamped on the frame plate. You could change an 8 to a ! as 18= 650cc.   Good luck, Howard

Thats a good Puzzle.  Early front end , 99 barrel, (well spotted Howard) later frame , later ignition switch position. could be a 650 or 99 capacity  with those cases .  It most likely to be 650 cc but could have issues with 650 pushrods and 99 barrel , or  99 pushrods with  650  valve springs !.  Could even be a very low compression engine with an 88 crank and 99 pistons ! .  Its all been done before to use up parts . If it runs and rides ok then  why not ?. I like the workshop,  mostly wood (kind to old bikes) with good light .

I have similar issues with my 63 ,  later  wrong headlamp ,clocks etc . Also not run yet , how far to go with checking ? .  Your rear guard looks odd , ?? . 

My year 1963 88SS has plain number 10xxxx on the frame.  No model number.  The engine is numbered 88SS/10××××/P.  No sign of a 12 or 122 on engine or frame.

Looking at your frame and the top of the  area cleaned off , it  would appear there are other numbers you have yet to reveal .

Hello again Dave,  The engine number that you quote is a Plumstead one. The slash P as a suffix signifies this.  The crankcases on these later bikes did not show the 122 Model number but it was still evident on the frame plate.   Is it possible that you have yet to remove enough paint to reveal it ?  Good luck, howard  

Kit, the steering damper you show on your images is a Norton Accessory that was available as an extra from 1962 for the SS Solo Models.  The kit had Part number SD/4 and with all the fittings it cost purchasers a measely £1 6s 8d.  regards, howard

Damper not really needed for solo riding but very usefull if leaning the bike against a lamp post ,tree ,wall or inside a van ,     locks the steering. Also cannot be ridden .anti theft !. Instant crash.

The numbers stamped on the frame are not Bracebridge or Plumstead numerals. Style is more like those for a Japanese engine.

Any chance of a clearer photo of the engine numbers???

The engine number is for a 650SS built just before Sep 1962 .

The barrel number 22709 was used for both 99 and 650 barrels but as Howard says the fins suggest that it belonged to a 99 in a previous life.  The problem with using an early 99 barrel on a 650 engine would be the size of the pushrod tunnels. These were generally not large enough to cope with the fatter SS pushrods operating inside without rubbing against each other or the barrel / heads lips.  The later 22710 99 / 650 barrel had larger P/R tunnels.

The cylinder head is the correct 650SS  22707 item.

The three barrels shown are left to right a 650 then late 99 and finally 88 dynamo engine. Your barrel appears to match the centre version. Note how the top fin of the centre barrel has a straight front  edge and hence more surface area where the head exhaust ports would be..

A question that you need to ask yourselfbefore you get too deep is what exactly are you wanting.

If you aspire to an 'as it came from the factory' machine, then go ahead and seek out the barrels/pistons and various other parts you need. Might become expensive mind you. Then you will find some people saying it isn't 'matching numbers' so it isn't a real one.  

If you are simply after a reliable 'old bike' then why worry too much. There is nothing wrong with a 'mongrel ' as long as it has been assembled well- my bikes engine, gearbox and frame certainly didn't leave the factory (factories?) at the same time but it is, to me, none the worse for it. It gets ridden a lot.

Be aware that 650 barrels came in spigots and non spigoted types, and you will need the correct type to go with your head. If the crank and rods are indeed 650, then the barrels you have must have already been modified to suit and should work just fine.

Add in that the pushrod issue is only really relevant on how you intend to use it. If you have the 'SS' valve springs (only needed to stop valve float at very high rpm ie. over 6500-7000rpm) and intend to use the full rev range, then the stiffer pushrods are a very good thing. If you intend to use it like most owners nowadays where a max of 5000 through the gears and cruising at a max of 4-4500rpm seems the norm, the earlier springs and slim pushrods will work perfectly well for you.

Best thing is that this club is made up of a lot of really helpful members that will offer advice and help to you.

Unless I missed it,  you haven't said whereabouts you live, but hopefully there is a local section not too far away.  You could find that meeting up with fellow 'Noccers' quite invaluable.

Keep asking. 

Regards,George 

Finding  "correct"  good quality parts  is now a  difficult process ,and as George says  pretty pointless if the bike works well . I do think that its prudent to look carefully at the whole bike as this should give you a good idea of the level of mechanical  competance of the previous owners  and go from there.