99S differences

What is the difference between a 99 engine and a 99S engine please.

hello do you meen 99c ,I have not heard of a 99s ,but have heard off the 99ss built from april1961 to sep1963 this engine shares the camshaft and pushrods and followers from the Norton Manxman 650

ah yes 99SS, thanks for the information , mine is a very rough manxman lookalike , guessing the previous owner ( deceased ) fancied to build himself one from accumulated parts as they seem to be a little thin on the ground. your input is much appreciated.

Previously wrote:

hello do you meen 99c ,I have not heard of a 99s ,but have heard off the 99ss built from april1961 to sep1963 this engine shares the camshaft and pushrods and followers from the Norton Manxman 650

Hi again, another query , my 99SS engine should have the camshaft etc of the Manxman, should it also have an SS head , by the NOC , May issue , the head information in it says SS heads have horizontal mounting studs, mine has the vertical stud configuration, have I the wrong head please.  

Back in 1965 John Hudson referred to my own 1959 '99' as a "99 Special" because it had quite a few of the optional factory extras, like large inlet valves, twin carbs, HC pistons, chrome mudguards, full rear chainguard etc.  I wrote to him with many technical queries during its first strip and rebuild.  His own view was that twin carbs weren't worth the bother but small-bore siamese pipes with an "SS silencer" gave a performance increase on the 99.  If your engine is a "14P" (1959 Model 99) maybe they labelled it because of the ex-works mods?  Cheers, Lionel

Hi again, another query , my 99SS engine should have the camshaft etc of the Manxman, should it also have an SS head , by the NOC , May issue , the head information in it says SS heads have horizontal mounting studs, mine has the vertical stud configuration, have I the wrong head please.  

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The factory built 99SS models, that were catalogued and available to Joe Public for a little under two years, were all stamped with 99SS on the back of the crankcases.  As opposed to just 99 or 99C on the other 600cc engines.

As part of the deal, you got an SS camshaft from the 650 engine as well as 650 barrels, 650 pushrods, twin Monobloc 376 carbs plus the option of a siamesed or standard exhaust. The most notable diffference between the 650SS and 99SS was the cylinder head. The 650 had the new splayed exhaust and twin carb job with horizontal carb mounting studs. The 99SS was sold with the old standard 1960 style 99 head with the old exhaust ports and mounting studs for the 2 into 1 car manifold.  Although, mounted in this area was now a special adapter which fitted between the head and allowed the use of twin carbs.  Strangely, in this head you had the bigger inlet valves of the 650 and some earlier 88 &99 heads plus the shorter but stiffer 650 type of valve springs.   Coil ignition was used for these engines.

Of interest, the 1962 sales brochure shows the 88SS wearing the 650 type of SS cylinder head but mentions that the 99SS has the standard head.  John Hudson once told me that the last couple of dozen 99SS bikes produced by the factory were actually fitted with the SS head but were never released to dealers as it was quickly realised that any of the previous 99SS bikes, still available, would then never sell.  Which begs the question of what happened to these proper 99SS specials?  Were the bikes re-engined with 650SS motors and sold as such or just dismantled for spares?

Hopefully attached is a photo of the 1959 to 1963 cylinder head used on the 99SS engines. Both the road and off-road Nomad version had this motor but with carb, ignition and other small differences.

Previously wrote:

Hi again, another query , my 99SS engine should have the camshaft etc of the Manxman, should it also have an SS head , by the NOC , May issue , the head information in it says SS heads have horizontal mounting studs, mine has the vertical stud configuration, have I the wrong head please.  

---------------------------------------------------------------------------------------------------------------------

The factory built 99SS models, that were catalogued and available to Joe Public for a little under two years, were all stamped with 99SS on the back of the crankcases.  As opposed to just 99 or 99C on the other 600cc engines.

As part of the deal, you got an SS camshaft from the 650 engine as well as 650 barrels, 650 pushrods, twin Monobloc 376 carbs plus the option of a siamesed or standard exhaust. The most notable diffference between the 650SS and 99SS was the cylinder head. The 650 had the new splayed exhaust and twin carb job with horizontal carb mounting studs. The 99SS was sold with the old standard 1960 style 99 head with the old exhaust ports and mounting studs for the 2 into 1 car manifold.  Although, mounted in this area was now a special adapter which fitted between the head and allowed the use of twin carbs.  Strangely, in this head you had the bigger inlet valves of the 650 and some earlier 88 &99 heads plus the shorter but stiffer 650 type of valve springs.   Coil ignition was used for these engines.

Of interest, the 1962 sales brochure shows the 88SS wearing the 650 type of SS cylinder head but mentions that the 99SS has the standard head.  John Hudson once told me that the last couple of dozen 99SS bikes produced by the factory were actually fitted with the SS head but were never released to dealers as it was quickly realised that any of the previous 99SS bikes, still available, would then never sell.  Which begs the question of what happened to these proper 99SS specials? Where the bikes re-engined with 650SS motors and sold as such or just dismantled for spares?

Hopefully attached is a photo of the 1959 to 1963 cylinder head used on the 99SS engines. Both the road and off-road Nomad version had this motor but with carb, ignition and other small differences.

Hello Phil,  the 650 barrels are 7mm longer than the 99 and the 99ss have a k2FC magneto.   I owned one back in the 70s and raced it too-  I thrashed the nuts off it, but it just came back for more - what a bike! I wish I had NOT SOLD IT what a FOOL I was!   Yours Anna J dixon

Previously wrote:

Previously wrote:

Hi again, another query , my 99SS engine should have the camshaft etc of the Manxman, should it also have an SS head , by the NOC , May issue , the head information in it says SS heads have horizontal mounting studs, mine has the vertical stud configuration, have I the wrong head please.  

---------------------------------------------------------------------------------------------------------------------

The factory built 99SS models, that were catalogued and available to Joe Public for a little under two years, were all stamped with 99SS on the back of the crankcases.  As opposed to just 99 or 99C on the other 600cc engines.

As part of the deal, you got an SS camshaft from the 650 engine as well as 650 barrels, 650 pushrods, twin Monobloc 376 carbs plus the option of a siamesed or standard exhaust. The most notable diffference between the 650SS and 99SS was the cylinder head. The 650 had the new splayed exhaust and twin carb job with horizontal carb mounting studs. The 99SS was sold with the old standard 1960 style 99 head with the old exhaust ports and mounting studs for the 2 into 1 car manifold.  Although, mounted in this area was now a special adapter which fitted between the head and allowed the use of twin carbs.  Strangely, in this head you had the bigger inlet valves of the 650 and some earlier 88 &99 heads plus the shorter but stiffer 650 type of valve springs.   Coil ignition was used for these engines.

Of interest, the 1962 sales brochure shows the 88SS wearing the 650 type of SS cylinder head but mentions that the 99SS has the standard head.  John Hudson once told me that the last couple of dozen 99SS bikes produced by the factory were actually fitted with the SS head but were never released to dealers as it was quickly realised that any of the previous 99SS bikes, still available, would then never sell.  Which begs the question of what happened to these proper 99SS specials? Where the bikes re-engined with 650SS motors and sold as such or just dismantled for spares?

Hopefully attached is a photo of the 1959 to 1963 cylinder head used on the 99SS engines. Both the road and off-road Nomad version had this motor but with carb, ignition and other small differences.

Hello Phil,  the 650 barrels are 7mm longer than the 99 and the 99ss have a k2FC magneto.   I owned one back in the 70s and raced it too-  I thrashed the nuts off it, but it just came back for more - what a bike! I wish I had NOT SOLD IT what a FOOL I was!   Yours Anna J dixon

 

 oh ,Anna J Dixon more confusion, the 650 barrels are longer ? ( as in taller , increased dimensions to make the 50 cc more I guess) what measurement would that be please , I dont know if my 99ss is 600 or 650cc, it has coil ignition, it has a  vertical stud inlet port , it has a twin carb adaptor with one of the carbs with a much reduced float bowl capacity, the port alignment when the manifold is on is atrocious, indicating to me that  it is an after market set up  rather than a factory fitted unit, has anyone got a photo of an original twin carb adaptor  please so I can determine if I am holding a genuine 99SS or a mock up. Your point that all 99SS engines had a mag ( because yours in 1970 had one ) ,is that a fact or is possible  it could have been converted back to a mag at anytime prior to your ownership .....many thanks for all the input.

Previously wrote:

Hi Adrian, As this thread is still ongoing. The attached pic of my engine block may help.

I have rebuilt this engine from sump plug to head steady and at the time tried to pin down details of the spec. There seems to be quite a bit of ‘misinformation’ to put it politely, around.

The 99ss 600cc had coil ignition, as far as I can see externally, the basic 600ss engine will look the same as standard of that year. You need to get inside to check things out, the camshaft was the main difference. Valve timing can be checked but unless you are up on 50/74/82/42 and things its not easy.

Ron.

I am unsure as to the cc , mainly for insurance reasons, I just always thought that 88 was 500cc, 99 was 600cc and then the SS was a 650  , also this is registered as mid 70's at present and needs to be reallocated a correct year reg number so i do need to sort the cc first, cam timing mathematis, like all mathematics, way beyond me, but i can build engines following a few timing dots, etc, (have a desm ducati too) my engine number is 99SS 7473, thanks for your input.

Just to add to the confusion!!  No-one has mentioned a year date for Adrian's engine yet but, from the 2 engine numbers mentioned in this thread, both must be later than 1960 as they don't have a year letter.  The last letter used was "R" for 1960. 

Phil, I wasn't aware that an SS head like your photo was available from 1959 - it's not in my Parts List book for that year or 1960, 1961/62, but I haven't got any SS Parts Lists.  The 1959 list only has the optional equipment of a head with larger inlet valves - subsequently made standard from 1960-on.  Mine is a standard looking head without the machined-off side fins but with large inlets;  Part No.21325A.  The same head was also available for the 88 and was normally fitted with twin carbs and high comp pistons.  This would have made a "pseudo-SS"!  Did the one in your photo have wider-splayed exhaust ports?  It doesn't look like it.

As the parts from this era can be pretty much "mix-&-match" it migh be difficult to estimate the actual capacity of an engine without measuring the bore size!  Even then it's not clear cut as a 500cc 88 may have been bored out to 67mm and the standard bore size of a 99 is 68mm - accurate measurement will be essential.

In my correspondence with John Hudson in 1965/66 he never mentioned an SS version at all!

Previously wrote:

Just to add to the confusion!!  No-one has mentioned a year date for Adrian's engine yet but, from the 2 engine numbers mentioned in this thread, both must be later than 1960 as they don't have a year letter.  The last letter used was "R" for 1960. 

Phil, I wasn't aware that an SS head like your photo was available from 1959 - it's not in my Parts List book for that year or 1960, 1961/62, but I haven't got any SS Parts Lists.  The 1959 list only has the optional equipment of a head with larger inlet valves - subsequently made standard from 1960-on.  Mine is a standard looking head without the machined-off side fins but with large inlets;  Part No.21325A.  The same head was also available for the 88 and was normally fitted with twin carbs and high comp pistons.  This would have made a "pseudo-SS"!  Did the one in your photo have wider-splayed exhaust ports?  It doesn't look like it.

As the parts from this era can be pretty much "mix-&-match" it migh be difficult to estimate the actual capacity of an engine without measuring the bore size!  Even then it's not clear cut as a 500cc 88 may have been bored out to 67mm and the standard bore size of a 99 is 68mm - accurate measurement will be essential.

In my correspondence with John Hudson in 1965/66 he never mentioned an SS version at all!

Previously wrote:

Previously wrote:

Hi Adrian, As this thread is still ongoing. The attached pic of my engine block may help.

I have rebuilt this engine from sump plug to head steady and at the time tried to pin down details of the spec. There seems to be quite a bit of ‘misinformation’ to put it politely, around.

The 99ss 600cc had coil ignition, as far as I can see externally, the basic 600ss engine will look the same as standard of that year. You need to get inside to check things out, the camshaft was the main difference. Valve timing can be checked but unless you are up on 50/74/82/42 and things its not easy.

Ron.

I am unsure as to the cc , mainly for insurance reasons, I just always thought that 88 was 500cc, 99 was 600cc and then the SS was a 650  , also this is registered as mid 70's at present and needs to be reallocated a correct year reg number so i do need to sort the cc first, cam timing mathematis, like all mathematics, way beyond me, but i can build engines following a few timing dots, etc, (have a desm ducati too) my engine number is 99SS 7473, thanks for your input.

Previously wrote:

Previously wrote:

Previously wrote:

Hi Adrian, As this thread is still ongoing. The attached pic of my engine block may help.

I have rebuilt this engine from sump plug to head steady and at the time tried to pin down details of the spec. There seems to be quite a bit of ‘misinformation’ to put it politely, around.

The 99ss 600cc had coil ignition, as far as I can see externally, the basic 600ss engine will look the same as standard of that year. You need to get inside to check things out, the camshaft was the main difference. Valve timing can be checked but unless you are up on 50/74/82/42 and things its not easy.

Ron.

I am unsure as to the cc , mainly for insurance reasons, I just always thought that 88 was 500cc, 99 was 600cc and then the SS was a 650  , also this is registered as mid 70's at present and needs to be reallocated a correct year reg number so i do need to sort the cc first, cam timing mathematis, like all mathematics, way beyond me, but i can build engines following a few timing dots, etc, (have a desm ducati too) my engine number is 99SS 7473, thanks for your input.

Hi Adrian, I think you have worked out that the extra 50cc of the 650 comes from length of the stroke,

600cc Bore 68mm Stroke 82mm. 650cc Bore 68mm Stroke 89mm.

If your engine is clearly marked 99 it’s a 597cc engine. The head type will not change its displacement.

It’s very unlikely that someone would have changed the crankshaft, this is where the extra stroke length is generated (that is 3.5mm up & 3.5mm down) and hence the extra 7mm in barrel length. But this extra length is not visible on the outside of the engine.

The number that is shown with the 99SS is not what is generally given as the engine No I would like to know what it is, in my case its not the works build No.

The number needed for the VOSA Doc will be the number on the drive side. You should be able to trace more details of the original bike from this.

Ron.

I am unsure as to the cc , mainly for insurance reasons, I just always thought that 88 was 500cc, 99 was 600cc and then the SS was a 650  , also this is registered as mid 70's at present and needs to be reallocated a correct year reg number so i do need to sort the cc first, cam timing mathematis, like all mathematics, way beyond me, but i can build engines following a few timing dots, etc, (have a desm ducati too) my engine number is 99SS 7473, thanks for your input.

Evening Gents,

You seem to be working it out.

Adrian, If you are able to turn the engine, you could confirm the stroke with a 6" length of welding rod. Another pair of hands would be helpful.

Rest the rod on top of the piston, turn the engine until the rod stops descending. Mark the rod with a fine felt tip pen, level with the top of the plug thread. Turn the engine again until the rod stops rising and make another mark in the same way.

You'll most likely have 82mm!

With the 650's (also 750's & 850's) having 7mm more stroke, also larger big end journals, the crankcases had to be enlarged to clear the big ends. I'm attaching a picture of the area of the drive side crank case where the difference is obvious, when compared with 600cc crankcases.

The steel rule is resting on the enlarged area of the 650 case.

I'm also experimenting with the text on this website to see if I can send more legible messages. So please bear with me if that doesn't work!

Paul.

I wrote a few minutes ago

Adrian, If you are able to turn the engine, you could confirm the stroke with a 6" length of welding rod. Another pair of hands would be helpful.

On second thoughts, maybe a 12" length of welding rod would be better. Certainly a lot easier.

Paul.

Previously wrote:

Adrian Gidney wrote Thursday 08:09

 

I am unsure as to the cc , mainly for insurance reasons, I just always thought that 88 was 500cc, 99 was 600cc and then the SS was a 650  , also this is registered as mid 70's at present and needs to be reallocated a correct year reg number so i do need to sort the cc first, cam timing mathematis, like all mathematics, way beyond me, but i can build engines following a few timing dots, etc, (have a desm ducati too) my engine number is 99SS 7473, thanks for your input.

Evening Gents,

You seem to be working it out.

Adrian, If you are able to turn the engine, you could confirm the stroke with a 6" length of welding rod. Another pair of hands would be helpful.

Rest the rod on top of the piston, turn the engine until the rod stops descending. Mark the rod with a fine felt tip pen, level with the top of the plug thread. Turn the engine again until the rod stops rising and make another mark in the same way.

You'll most likely have 82mm!

With the 650's (also 750's & 850's) having 7mm more stroke, also larger big end journals, the crankcases had to be enlarged to clear the big ends. I'm attaching a picture of the area of the drive side crank case where the difference is obvious, when compared with 600cc crankcases.

The steel rule is resting on the enlarged area of the 650 case.

I'm also experimenting with the text on this website to see if I can send more legible messages. So please bear with me if that doesn't work!

Paul.

Aha Ron!  The plot thickens!  My 1959 parts list PS 206 has that cylinder head in the 'Optional Equipment' section at the back (red type-face).  This one is presumably what my bike has, although I have no idea whether the inlet ports are at wider centres than the earlier 'standard' head - haven't got one to compare it with!  Apparently it was available from some time in 1958 (Steve Wilson says from May).  Then it was supposedly fitted as standard from 1960 - YET there is another head mentioned in literature which says/implies they had another, different new head in 1960!  Steve Wilson taks about the milled off crosses between the exhaust and inlet rocker spindle plates.  Mick Walker's book just says it had improved cooling by way of "increased and deeper finning".  It sounds as if they are talking about two different heads - one from 1958 and one from 1960.  The "new" head 21325A from the 1959 optional list and the "new" head with milled off sections are obviously different heads yet the head assembly with valve guides - p/n R12-2/136 - is the same as the one listed in both PS 208 for 1960, and PS 214 for 1961/62!

The Supplementary Spare Parts List PS 208 refers to PS 206 (1959) for any parts not listed.  It doesn't list a bare cylinder head but it lists the large inlet valve as per the 1959 optional version - p/n 17221 - as you would expect.  By "Elementary Sherlock Holmes deduction" using these lists, the head listed as extra for 1959 and standard for 1960-62 should be the same!

Confused?  You should be!

Re: camshafts - I've not even gone there but I was told by John Hudson that mine had the Daytona type with Quietening Ramps ("QR").  This is confirmed in many sources as the issue for the 1959 99.  Like a fool I sold the original camshaft to Barry Lawton (Syd's son) who wanted to use it in his Domiracer on the I.o.M.!  Dunno if he won any races with it!  I then bought a cheap 88 engine (for £5!) which had an SS camshaft in!  I used that one in my 99 but kept my original radius-based cam followers - couldn't afford a set of new SS ones!  I have since had them re-faced flat by the same engineering workshop that rebored my 99 barrels (and who do work for Norman White at Thruxton).  So- IF I reassemble the engine with what I've got, it will be an SS spec cam & followers but not with twin carbs - I really can't be ar*ed to go that route!

Cheers, Lionel

Previously wrote:

Previously wrote:

Previously wrote:

Previously wrote:

Hi Adrian, As this thread is still ongoing. The attached pic of my engine block may help.

I have rebuilt this engine from sump plug to head steady and at the time tried to pin down details of the spec. There seems to be quite a bit of ‘misinformation’ to put it politely, around.

The 99ss 600cc had coil ignition, as far as I can see externally, the basic 600ss engine will look the same as standard of that year. You need to get inside to check things out, the camshaft was the main difference. Valve timing can be checked but unless you are up on 50/74/82/42 and things its not easy.

Ron.

I am unsure as to the cc , mainly for insurance reasons, I just always thought that 88 was 500cc, 99 was 600cc and then the SS was a 650  , also this is registered as mid 70's at present and needs to be reallocated a correct year reg number so i do need to sort the cc first, cam timing mathematis, like all mathematics, way beyond me, but i can build engines following a few timing dots, etc, (have a desm ducati too) my engine number is 99SS 7473, thanks for your input.

Hi Adrian, I think you have worked out that the extra 50cc of the 650 comes from length of the stroke,

600cc Bore 68mm Stroke 82mm. 650cc Bore 68mm Stroke 89mm.

If your engine is clearly marked 99 it’s a 597cc engine. The head type will not change its displacement.

It’s very unlikely that someone would have changed the crankshaft, this is where the extra stroke length is generated (that is 3.5mm up & 3.5mm down) and hence the extra 7mm in barrel length. But this extra length is not visible on the outside of the engine.

The number that is shown with the 99SS is not what is generally given as the engine No I would like to know what it is, in my case its not the works build No.

The number needed for the VOSA Doc will be the number on the drive side. You should be able to trace more details of the original bike from this.

Ron.

. I attach a pic of my inlet manifold but I can’t guarantee it’s a genuine Norton part, no part No. Unfortunately there are two sizes.

hope that  manifold is not resting on  the wifes best table cloth  ???, ha ha....thanks very much i will inspect mine in great detail tomorrow to compare.

Previously wrote:

Previously wrote:

Adrian Gidney wrote Thursday 08:09

 

I am unsure as to the cc , mainly for insurance reasons, I just always thought that 88 was 500cc, 99 was 600cc and then the SS was a 650  , also this is registered as mid 70's at present and needs to be reallocated a correct year reg number so i do need to sort the cc first, cam timing mathematis, like all mathematics, way beyond me, but i can build engines following a few timing dots, etc, (have a desm ducati too) my engine number is 99SS 7473, thanks for your input.

Ron Corbin wrote Thursday 20:39

Hi Adrian, I think you have worked out that the extra 50cc of the 650 comes from length of the stroke,

600cc Bore 68mm Stroke 82mm. 650cc Bore 68mm Stroke 89mm.

If your engine is clearly marked 99 it’s a 597cc engine. The head type will not change its displacement.

It’s very unlikely that someone would have changed the crankshaft, this is where the extra stroke length is generated (that is 3.5mm up & 3.5mm down) and hence the extra 7mm in barrel length. But this extra length is not visible on the outside of the engine.

The number that is shown with the 99SS is not what is generally given as the engine No I would like to know what it is, in my case its not the works build No.

The number needed for the VOSA Doc will be the number on the drive side. You should be able to trace more details of the original bike from this.

Ron.

 

Evening Gents,

You seem to be working it out.

Adrian, If you are able to turn the engine, you could confirm the stroke with a 6" length of welding rod. Another pair of hands would be helpful.

Rest the rod on top of the piston, turn the engine until the rod stops descending. Mark the rod with a fine felt tip pen, level with the top of the plug thread. Turn the engine again until the rod stops rising and make another mark in the same way.

You'll most likely have 82mm!

With the 650's (also 750's & 850's) having 7mm more stroke, also larger big end journals, the crankcases had to be enlarged to clear the big ends. I'm attaching a picture of the area of the drive side crank case where the difference is obvious, when compared with 600cc crankcases.

The steel rule is resting on the enlarged area of the 650 case.

I'm also experimenting with the text on this website to see if I can send more legible messages. So please bear with me if that doesn't work!

Paul.

Before we put Adrian into a flat spin, is the crankcase bulge more subtle than it looks, or is it just machined inside for 650cc. or are we learning something here. See pic.

Ron

my head is off... not the one on my shoulders of course, so if i  go to B.D.C and measure to the  top of cylinder barrel, then turn engine to T.D.C and measure the protrusion of piston crown, deduct that measurement from the first measurement that will be the stroke ? like i said  my mathematics.... not so good

Previously wrote:

Aha Ron!  The plot thickens!  My 1959 parts list PS 206 has that cylinder head in the 'Optional Equipment' section at the back (red type-face).  This one is presumably what my bike has, although I have no idea whether the inlet ports are at wider centres than the earlier 'standard' head - haven't got one to compare it with!  Apparently it was available from some time in 1958 (Steve Wilson says from May).  Then it was supposedly fitted as standard from 1960 - YET there is another head mentioned in literature which says/implies they had another, different new head in 1960!  Steve Wilson taks about the milled off crosses between the exhaust and inlet rocker spindle plates.  Mick Walker's book just says it had improved cooling by way of "increased and deeper finning".  It sounds as if they are talking about two different heads - one from 1958 and one from 1960.  The "new" head 21325A from the 1959 optional list and the "new" head with milled off sections are obviously different heads yet the head assembly with valve guides - p/n R12-2/136 - is the same as the one listed in both PS 208 for 1960, and PS 214 for 1961/62!

The Supplementary Spare Parts List PS 208 refers to PS 206 (1959) for any parts not listed.  It doesn't list a bare cylinder head but it lists the large inlet valve as per the 1959 optional version - p/n 17221 - as you would expect.  By "Elementary Sherlock Holmes deduction" using these lists, the head listed as extra for 1959 and standard for 1960-62 should be the same!

Confused?  You should be!

Re: camshafts - I've not even gone there but I was told by John Hudson that mine had the Daytona type with Quietening Ramps ("QR").  This is confirmed in many sources as the issue for the 1959 99.  Like a fool I sold the original camshaft to Barry Lawton (Syd's son) who wanted to use it in his Domiracer on the I.o.M.!  Dunno if he won any races with it!  I then bought a cheap 88 engine (for £5!) which had an SS camshaft in!  I used that one in my 99 but kept my original radius-based cam followers - couldn't afford a set of new SS ones!  I have since had them re-faced flat by the same engineering workshop that rebored my 99 barrels (and who do work for Norman White at Thruxton).  So- IF I reassemble the engine with what I've got, it will be an SS spec cam & followers but not with twin carbs - I really can't be ar*ed to go that route!

Cheers, Lionel

 

Hello Lionel.

Yep got it, err well may be not! I’ve sent a pic of my 1961 99 engine. This is a R12-2/136 cylinder head 99.9% certain. The milled section between the rocker spindles can be seen. Extra cooling fin area, easiest clue to spot is the finning above the exhaust ports is now all horizontal. It’s not that obvious but the inlet manifold fixings are just that bit further way from the edge of the enlarged ports. I think this fits Steve Wilson’s / Mick Walker’s description.

If you can get hold of a set of 650cc pushrods this would be a nice upgrade, they would be used one’s, not available new but they are very nice lightweight hollow aluminium (special grade) tapered each end, people say barrel shape. You know, red line 8000rpm.

Regards Ron.

Hello Lionel.

Yep got it, err well may be not! I’ve sent a pic of my 1961 99 engine. This is a R12-2/136 cylinder head 99.9% certain. The milled section between the rocker spindles can be seen. Extra cooling fin area, easiest clue to spot is the finning above the exhaust ports is now all horizontal. It’s not that obvious but the inlet manifold fixings are just that bit further way from the edge of the enlarged ports. I think this fits Steve Wilson’s / Mick Walker’s description.

If you can get hold of a set of 650cc pushrods this would be a nice upgrade, they would be used one’s, not available new but they are very nice lightweight hollow aluminium (special grade) tapered each end, people say barrel shape. You know, red line 8000rpm.

Regards Ron.

Previously wrote:

Previously wrote:

Previously wrote:

Previously wrote:

Previously wrote:

Hi Adrian, As this thread is still ongoing. The attached pic of my engine block may help.

I have rebuilt this engine from sump plug to head steady and at the time tried to pin down details of the spec. There seems to be quite a bit of ‘misinformation’ to put it politely, around.

The 99ss 600cc had coil ignition, as far as I can see externally, the basic 600ss engine will look the same as standard of that year. You need to get inside to check things out, the camshaft was the main difference. Valve timing can be checked but unless you are up on 50/74/82/42 and things its not easy.

Ron.

I am unsure as to the cc , mainly for insurance reasons, I just always thought that 88 was 500cc, 99 was 600cc and then the SS was a 650  , also this is registered as mid 70's at present and needs to be reallocated a correct year reg number so i do need to sort the cc first, cam timing mathematis, like all mathematics, way beyond me, but i can build engines following a few timing dots, etc, (have a desm ducati too) my engine number is 99SS 7473, thanks for your input.

Hi Adrian, I think you have worked out that the extra 50cc of the 650 comes from length of the stroke,

600cc Bore 68mm Stroke 82mm. 650cc Bore 68mm Stroke 89mm.

If your engine is clearly marked 99 it’s a 597cc engine. The head type will not change its displacement.

It’s very unlikely that someone would have changed the crankshaft, this is where the extra stroke length is generated (that is 3.5mm up & 3.5mm down) and hence the extra 7mm in barrel length. But this extra length is not visible on the outside of the engine.

The number that is shown with the 99SS is not what is generally given as the engine No I would like to know what it is, in my case its not the works build No.

The number needed for the VOSA Doc will be the number on the drive side. You should be able to trace more details of the original bike from this.

Ron.

. I attach a pic of my inlet manifold but I can’t guarantee it’s a genuine Norton part, no part No. Unfortunately there are two sizes.

hope that  manifold is not resting on  the wifes best table cloth  ???, ha ha....thanks very much i will inspect mine in great detail tomorrow to compare.

Previously wrote:

Previously wrote:

Just to add to the confusion!!  No-one has mentioned a year date for Adrian's engine yet but, from the 2 engine numbers mentioned in this thread, both must be later than 1960 as they don't have a year letter.  The last letter used was "R" for 1960. 

Phil, I wasn't aware that an SS head like your photo was available from 1959 - it's not in my Parts List book for that year or 1960, 1961/62, but I haven't got any SS Parts Lists.  The 1959 list only has the optional equipment of a head with larger inlet valves - subsequently made standard from 1960-on.  Mine is a standard looking head without the machined-off side fins but with large inlets;  Part No.21325A.  The same head was also available for the 88 and was normally fitted with twin carbs and high comp pistons.  This would have made a "pseudo-SS"!  Did the one in your photo have wider-splayed exhaust ports?  It doesn't look like it.

As the parts from this era can be pretty much "mix-&-match" it migh be difficult to estimate the actual capacity of an engine without measuring the bore size!  Even then it's not clear cut as a 500cc 88 may have been bored out to 67mm and the standard bore size of a 99 is 68mm - accurate measurement will be essential.

In my correspondence with John Hudson in 1965/66 he never mentioned an SS version at all!

Hi.Lionel, My 99ss left the factory in June 1961 ( Slimline ). Your suppositions for the Sports Special are as mine.

From my Original Parts Book 1961/62, PS214 that includes supplementary list for 88SS 99SS & 650ss + the Optional Equipment list.

Part No :- " 21325A Polished cylinder head, complete with valve guides and large inlet valve seat insert ". For Models 88, 99. STD and D/L Price £20 2 6

Part No :- 18542 Inlet manifold (for dual carburettor fixing) For Model 88 99 STD Price £1 17 2Also listed are various High Compression pistons 8.9 9.45 10.2

Now, like you I think that this upgrade was the basis of the New Head introduced in 1960.

This is where the inlet manifold fixing centres changed, 1.5in to 1.625in

Part No :- R12-2 /136. The large inlet valve ( Known as V195 ) now standard. 22707K cast in head.

From the Parts List I can see the difference in various 99SS parts.

Cylinder Head. same part no for 99 & 99SS £18 18 0.

Valves, no different Number given, assume the same.

Cylinder Barrel 99 = 22709. 99SS = 22709D. By the way 650SS = 23263

Valve Springs 99 = 19302inner 19303outer. 99SS = 22839 inner 22838 outer. Note. same as 650SS.

Push Rods 99 = M14/82 IN M14/82 EX. 99SS = S650/82 IN S650/82EX Note. same as 650SS.

Camshaft 99 = 21225 99SS = 22729 Note same as 650SS

A question. I think we agree that models share some parts, but does the 99SS share 650SS parts or does the 650SS share 99SS parts. Which came first.

Ron C.

 hello all 650 Manxman Was the First to have the Downdraft Cylinder head First one built was on NOVEMBER 7TH 1960  MY  Manxman was Built on the 28th december 1960 and as not got a R stamped on As it was a Export Bike The Cylinder Head Part Number is s650/136, barrel part number 23263, 650 as 3.5 mm extra bottom flange ,And wider cutout for connecting rod ,piston where made by BHB ,My manxman its Standard bore part number for piston are 23268LH and23269RH  Supplied over sizes +010 +020 +030 camshaft part number 22729 hope this helps Yours Anna J Dixon

 

Previously wrote:

Just to add to the confusion!!  No-one has mentioned a year date for Adrian's engine yet but, from the 2 engine numbers mentioned in this thread, both must be later than 1960 as they don't have a year letter.  The last letter used was "R" for 1960. 

Phil, I wasn't aware that an SS head like your photo was available from 1959 - it's not in my Parts List book for that year or 1960, 1961/62, but I haven't got any SS Parts Lists.  The 1959 list only has the optional equipment of a head with larger inlet valves - subsequently made standard from 1960-on.  Mine is a standard looking head without the machined-off side fins but with large inlets;  Part No.21325A.  The same head was also available for the 88 and was normally fitted with twin carbs and high comp pistons.  This would have made a "pseudo-SS"!  Did the one in your photo have wider-splayed exhaust ports?  It doesn't look like it.

As the parts from this era can be pretty much "mix-&-match" it migh be difficult to estimate the actual capacity of an engine without measuring the bore size!  Even then it's not clear cut as a 500cc 88 may have been bored out to 67mm and the standard bore size of a 99 is 68mm - accurate measurement will be essential.

In my correspondence with John Hudson in 1965/66 he never mentioned an SS version at all!

hello  the 88,500cc  barrel as 8 cooling fins and 99/650 as 9 cooling fins the 650 as a long flange at the bottom for the longer stroke the 99ss crankcase are the same as 650 Manxman ,not all 650s where SS there was a DE-LuXed  model and a standard model from October 1961 to august 1962 as the 99 models allso ended in 1962 as Bracebridge Street works closed and every thing moved to Plumsted and wolverhamton AMC works hope this helps  yours anna j dixon

Previously wrote:

Previously wrote:

Hi Adrian, As this thread is still ongoing. The attached pic of my engine block may help.

I have rebuilt this engine from sump plug to head steady and at the time tried to pin down details of the spec. There seems to be quite a bit of ‘misinformation’ to put it politely, around.

The 99ss 600cc had coil ignition, as far as I can see externally, the basic 600ss engine will look the same as standard of that year. You need to get inside to check things out, the camshaft was the main difference. Valve timing can be checked but unless you are up on 50/74/82/42 and things its not easy.

Ron.

I am unsure as to the cc , mainly for insurance reasons, I just always thought that 88 was 500cc, 99 was 600cc and then the SS was a 650  , also this is registered as mid 70's at present and needs to be reallocated a correct year reg number so i do need to sort the cc first, cam timing mathematis, like all mathematics, way beyond me, but i can build engines following a few timing dots, etc, (have a desm ducati too) my engine number is 99SS 7473, thanks for your input.

 hello your engine number this stamped at the front left hand side just above the end of the camshaft tunnel and shud start with 96xxx or 97xxx so theres  number missing and the 99ss was only built for 14 months ,march 1961 to august 1962  yours anna j dixon

my engine  is stamped 14 and its number is 98123, front left hand side, the 99ss  7473 being stamped to the rear just inboad of the crankcase breather outlet. never got around to any measuring this weekend , maybe one night this week, thanks for ALL you wonderful people's  input

Previously wrote:

my engine  is stamped 14 and its number is 98123, front left hand side, the 99ss  7473 being stamped to the rear just inboad of the crankcase breather outlet. never got around to any measuring this weekend , maybe one night this week, thanks for ALL you wonderful people's  input

Hello adrian  Now This Machine was built  at the end of May 1961 ,The 7473 number is the Norton workshop Number  And You (99SS) As A bore of 68mm and a Stroke of 82mm 600cc 

I had a (99ss) Cafe racer And I thrashed the hell out of it And It just wanted more thrashing And I raced it too , well thats was back in the 70s  My dad Sold It When I was At sea ? 

Yours   Anna J Dixon   Happy thrashing??   Ps Theres not much diffrence between the top speed  this 99SS and the speed of the 650ss  ??? About 118 mph

Previously wrote:

Hi, I realise we are well into anorak territory here but if there is anyone still interested!

It seems from all the inputs so far the important bits are :-

Crankcase, as the newly introduce 650cc machines.

Barrels, are also 650cc?

Cylinder Head, As new design for standard 99 in 1960, but with uprated valve springs, 650cc spec.

Camshaft, Hotter cam as used in 650’s.

The barrel base flange on my 99SS barrels is about 12.3mm. Can anyone give the thickness of an early 650cc flange? As the 99SS & 650cc machines use the same pushrods, suggests to me that the extra 7mm of stroke is accommodated somewhere else. Shorter Conrods? The 650cc bigend journal size was larger, so a new rod, was this new rod shorter than the pervious 600cc rod? I know from my barrels there was plenty of ‘ unused ‘ bore at the bottom end, so the working stroke could be further down in the bore for the 650cc. Does anyone have any rod length data? Different height pistons are possible but I can’t see this from parts list.

sorry to cause you guys a headache , your leaving me behind now  , shorter rod means a greater throw on the crankpins would be necessary which uses up the spare unused barrel length which in turn increases the cc to 650 , so a different crank for 650 , with moded crankcase to accomodate and an increased bore size too.  is that right

many many thanks to all for all the info , it is very much appreciated.... happy motorcycling to you all.