Wednesday, 4 December 2013
-Richard- This is Dennis Minett riding Beart's over-bored 515cc engined machine which Francis had built to break the 750cc class Outer Circuit lap record held since 1930 by Bill Lacey with his special 588cc CS1 at over 110mph. The attempt was made on June 25th 1938 during the Cup Day meeting with Minett pushing the lap speed up to 117.19mph. Minett also rode in the 3 lap Gold Star Scratch Race winning with ease and recording a fastest lap at 115.02mph.
Dennis Minett also held the 500cc class lap record at 116.36mph with the same machine (499cc engine) and although both records were broken ( just! ) by supercharged Triumph twins, they remain the fastest speeds by a single cylinder machine around Brooklands and this also highlights Minett's riding ability.
Sunday, 1 December 2013
Friday, 29 November 2013
Thursday, 28 November 2013
-SG- My good friend Barry Tyreman has had some CR mainshaft bottom gears (CS 22g) made for the CS box. These have 17 teeth and are run with the better lasting 25T layshaft bottom gear. They were used from 1926 to 1930. A scan of the relevant section of the spares list is above.
He does not have many but they are available right now! Price is £80 each plus post and packing. Barry is not on email, but send us a message if you're interested and we will pass on his phone number.
Tuesday, 26 November 2013
Thierry in France
"Thierry: he number on the base of the barrel is 60xxx; there is no number on the crankcase, which may have been replaced at some time. The number on the barrel belongs to a 596cc Model 30, shipped on 8 November 1934 to a Geneva dealer "Demont", with an optional dynamo (Bosch) and a speedo. The frame number could have been 55xxx but unfortunately the page that contains my Norton's details is messy and the numbers are unclear. The engine has some interesting racing parts fitted: a full bronze head, magnesium cambox and the central oil feed through the camshaft to the cambox."
Sunday, 24 November 2013
-SG- John in the UK has recently come by the CS1 head illustrated which seems to be pre-'35 (it has an 18mm plug but it also has an internally threaded exhaust port). He would like to swap if possible for a reasonable 1927 Model 18 head or parts for his 1923 16H project. Main items wanted for this are a footrest assembly and good inner timing cover. Emails will be forwarded!
Wednesday, 20 November 2013
-SG- Juris in Latvia has raised some interesting questions on this subject with this old Norton bore and we invite those who have practical experience of such matters to let us have their views. Juris says:
"I am working on several Norton engines at the moment, two CS1 models of 1930 and 1938 and one Model 18 of 1930. As you know these have different lubrication systems with the 1930 Model 18 being of "total loss" and the other two of the "dry sump" type. I have got specially made forged higher compression aluminium pistons for all three and the pistons have been machined to use modern VW rings 1.75/2/3 mm. I have used modern technology Flex-Hone instruments after honing the cylinders instead of the old fashioned polishing with "Brasso" liquid metal polish as today's automotive engineering technology advises the use of a cross-hatch pattern of tiny uniform scratches on the cylinder surface to provide oil retention, better compression and less oil consumption. The modern automotive rings have higher precision and are also usually honed on the outside diameter for perfect roundness. The top ring is chromium plated as is the oil ring.
The cause of my concern is the use of the modern (high pressure) oil ring in an older engine with total loss lubrication, like the Model 18 of 1930. The ring has a coil spring which is made to fit on the inside of the ring and the pressure outwards is very substantial, compared to old-fashioned solid cast iron rings. I have successfully used forged pistons with modern automotive rings in my 1913 "total loss" REX/JAP 6HP (770cc) engine for around 4000 kilometres. This is lubricated by vegetable oil and no oil rings were fitted as this type of engine had been designed to burn a certain amount of oil. I am now wondering whether I should:
- Discard the oil ring and use the piston in my 1930 Mod 18 with only 2 compression rings, or perhaps fit a suitable width 3rd compression ring in the oil ring groove.
- Discard the inner coil spring under the oil ring and use the oil ring without the inner spring.
- Shorten the inner coil spring of the oil ring to allow for less pressure on the cylinder walls to save them from wear and to let through more oil.
I am going to use the modern oil rings with reduced spring pressure in my dry sump OHC engines. Needless to say the modern mineral oils available seem to be far superior to what was available to the rider back in 1930 or even 1938, with all those antiwear and antioxidant additives etc."
My personal experience of such matters is way out of date so I sent a copy of Juris' message to Chris in Scotland whose business involves refurbishing Vintage and Post Vintage engines and has much experience in such matters. Here's what Chris recommends:
- In 'total loss' engines, use three plain compression rings as per the original design.
- In relatively low flow dry sump engines - for instance Model 25s or Moore CS1s - use two compression rings and one stepped oil control ring.
- In higher flow dry sump systems such as the CS1s Juris is working on, use a normal oil control ring of orthodox type. I take the view that it is beneficial to increase slightly the diameter of the holes behind or just below the oil control ring.
- If you are using a modern piston then it's not a good idea to remove the spring behind the oil control ring.
Although he has no connection with the firm, Chris gets his rings from an outfit called Cox and Turner - which specialises in rings of all types. They can be contacted as follows: firstname.lastname@example.org
Monday, 18 November 2013
|Bill Lacey and CS1 Norton|
-SG- Arthur Tyler was a works rider for Raleigh and Vincent during the early thirties and this 'private' (not 'press') photo come from his personal album - courtesy of his son Stuart Tyler and Paul Ingham.
It shows Bill Lacey - I assume taken at Montlhery - after his successful Hour Record foray in 1931 at 110 mph. Because Lacey helpfully stood behind the bike, one can see considerable detail; no brake pedal as such, just the brake arm extended; rear set footrests; twin float down draught carburettor; rather spindly hand change lever on the NS type Sturmey box. Lacey's track Nortons were all fitted with Druid ES forks (like the CJs and JEs but probably the larger size).
Regrettably, his very successful efforts with Nortons are rather overshadowed by his earlier and longer spell with Grindlay Peerless. He said, at a talk he gave back in the eighties which I attended, that he had a spate of con rod breakages with his Carroll engined bikes and the powers-that-were at the factory did not take kindly to his complaints about inaccurate machining or his suggestion that they could learn a thing or two in that area from the likes of Velocette and Sunbeam!
Friday, 15 November 2013
Wednesday, 13 November 2013
-SG- Here's an uncommon shot of Bennett and his 1925 Senior TT Works Norton. The oil pump adjuster is visible on the oil pump cover (it was simplified in '26 and onwards) and one can see the drooping footrest - damaged when Bennett had a minor 'off' during the event. Note also the front brake - still very small but with brake arm pointing forward. Small or not, I can tell you from personal experience this makes otherwise rather useless small Vintage brakes infinitely better!