88SS and 88 crankshaft

engine VS  complete bike

All 500 are "magneto" crankshaft????

The regular dynamo AND alternator crank journal center oil bore was 1", the uprated crank was reduced to 5/8"alternator style only.

The head you have is S650/136 commonly called down draft and used on 650/500ss but "will fit" on 600.

The early 500ss and 600ss used the  88SS/136  head.

bulge or no bulge cases are not an issue for alternator 500, bulge is only necessary for 650.

All the proper named  SS bikes were alternator fitted  . Before that you could get  bigger valves ,polished ports etc on Dynamo bikes . Don't think crank breakage was much of an issue with the 88  and removing any internal stress raiser  probably more important than chasing a hard to find SS crank.

If you don't have a charging system you won't be the only occasional night rider who relies on modern LED lamps and total loss.

" I am wondering if replacing the 88 crank with a 88ss crankshaft would be of any benefit (except for the alternator mounting)...

I have been building car engines since the late 60's and since the late 80's I have been doing NHT and a few BSA twins. This includes some "specialy" engines.

In my opinion the 122 in later 62+SS tune with the S650/136 head and the SS cam would have easily been subject to crank breakage. Otherwise why would the factory make the uprated SS crank. The small bore cranks are quite rare. I was able to source one  NOS never installed $1000.

Putting big valves in a very inferior early head on a pre SS cam engine is OK for bragging rights or a little extra grunt, but I would not waste my time.

I will eventually finish my 62(type) 122 ss engine with SS cam and S650/136 head and standard bore genuine "SS" barrels. Many folks don't even know what is special about SS barrels! While I will cheat on the carbs and manifolds, the break in and initial tune will be on my chassis brake-dyno.

My 63 "20" slimline roller with 59(cases) 122 engine built as (62) 88SS+ bike will be finished as full street legal equipment and my own oil filter system.

Yes David - I think you're correct about crankshafts.  I doubt very much that the 88SS which won the 500cc Class of the Thruxton 500 Mile race three times between 1960 and 1962 would have achieved that feat with a standard 88 crankshaft.  In 1962 it was second overall and if Phil Read had not been on the leading 650SS it would have won.  Team orders were also around in those days it seems !!  Those 88SS cranks were nearly unbreakable.  Good  Luck,  Henry.

The Works Domiracer 500 is described as having a strengthened crankshaft. If you look at the cutaway diagram of this motor is is fairly obvious that the conrods have larger big end shoulders and caps. The crankshaft centre web is also massive and more like a 650 item. John Hudson said that the Engine Development Department at Bracebridge had experimented with larger big ends in order to improve the reliability of both the 500cc and 600cc engines when they were raced. He also claimed that Triumph conrods with 1.60" journals were tried in some engines. Many years ago a Nomad 500cc engine was discovered with 1.75" journals.

Henry seems to be asking about factory configuration differences.

I certainly do not know anything about which race bike hardware Howard is refering to...

It would seem that NO factory race shop equipment is readily available here in the USA. Even finding a production 62 SS crank is super rare here. Even USA based claimed  Norton experts are/were unaware of the small bore cranks.

The picture you provide of the open cases look to be T2153 which are likely not 62 alternator (bulge) cases as they also have weld reinforcement and signs of the central cast bar being carved out. It is probably a dynamo case like the ones on the table right behind me....

Micheal

There is nothing particularly notable from Phils pix about cams/.

" I immediately spotted the needle roller bearings for the camshaft"      ?  HOW... LOL

 Why do you think that is special? How is a MK4 different from a MK3? Especially  for a 500?

"But as far as I can see from the diagram, it is not oil-fed as my Dunstall cam is- it has a delivery hole on each lobe, but I was never able to figure out the correct feed- this entered somehow where the disc breather valve goes".

None of this is new, despite your excitement or inexperience with Dunstall equipment.

 It would be nice if we could return to the OP's inquiry and open a new thread for your satisfaction....

I know from personal experience that 88SS cranks do fail.

I was  rebuilding my 1962 88SS engine (with 1.5" journals) recently. The bike was raced in South Australia by a well known motorcycle journalist for a number of years.

As a matter of course each time I rebuild a h.w.t. engine I always send the crank out for crack testing.

Sure enough there was a crack about half way round where the mainshaft meets the cheek.

It was enough to scrap the bottom end.

Definitely an 88SS crank as both sides were stamped 88SS.

Ian - Of course everything can fail especially after the perilous conditions for an engine met in racing.  My point was not that they never fail - just that they are a lot more reliable than the standard versions as fitted to the 88 and 99.  I often wondered why the strengthened big-end journal of the 88SS did not get into the 99SS but I suppose as it would have a very limited production run,  with the Export 650 already in production, the Factory considered it not worthwhile.

I should also like to point out to David and any other overseas readers that the Thruxton 500 Mile races were for factory produced road bikes not racers.  The races began in 1955 and had run their course by the early 1970s.  The rules were such that any particular model could only be entered three times unless substantial design changes had been made by the factory.  Certain safety features were permitted eg racing tyres, racing brake linings, single seats and factory produced rear-set footrests. Centre stands were removed. The races were originally for classes of 350cc and under ; 351cc to 1000cc singles and 351cc to 1000cc multis for 9 hours with two riders sharing the bike.  Nortons did enter the races in the fifties with little success with Inters and wideline Dominators.  Attrition was high.  In 1958 a new format was introduced to get more factory interest.  Classes of up to 250cc, 500cc and Unlimited capacity were established and the race was set at 500 Miles.  Top riders were encouraged to ride by the factories wanting to sell their products to young men with bulging pockets.  The pairing of  Mike Hailwood and Dan Shorey won in 1958 on a Triumph T110.  The clear favourites of Bob McIntyre and Derek Powell were second on a RE Constellation.  In 1960 Phil Read and Brian Setchell were fighting for the lead on a Syd Lawton 99SS but retired on lap 131 with a split petrol tank.  Then the dealer, Denis Parkinson, entered an 88SS in 1960, 61 and 62 and was victorious in the 500 Class for those three years. Also, Syd Lawton,  entered a 650SS in 1962,63 and 64 and won the Unlimited Class three years in a row.  It was widely believed that in 1962 as the 88SS of Fred Swift caught the leading 650SS  of Phil Read, team orders were made, to keep the 650 in the lead.  So it was that the 650SS won and the 88SS was second.  Under the three year rule the Nortons were unable to get entries for subsequent races and the Atlas was entered as a Matchless ridden by Peter Williams in 1965.  Paul Dunstall took up the challenges with his 750s until the Factory Commandos came along in the seventies. 

My point is that the 88SS won the top endurance race of the day three years running and was never beaten in its class.  The special crankshaft kept it all together and made that history possible.  Not a bike to be underestimated.  Cheers, Howard

OK David, what is special about SS barrels please?

For the enlightenment of we lesser mortals.

OK, pressure fed cam = good, but where was the crankcase breather repositioned to? Not obvious in the pictures/drawings.

Just wondering. 

George 

George, found this online in a Paul Dunstall catalogue, which gives a little more info about the cam lubrication mod.

Andy 

Hello Alan - The 88SS barrels (and 99SS, 650 and Atlas) had wider pushrod tunnels within the casting. Their part number was 20712B.  The Model 88 barrel used on the De-Luxe and Standard had part number 20712.  The extra width was required to accommodate the hollow-blown alloy pushrods used in the SS models which had a much bigger diameter for most of their length.  If these fatter pushrods were used in a standard barrel they touched the casting in the tunnels and were weakened very quickly.   The 88SS barrels are usually stamped SS on the top face.  Cheers,  Howard.