Straight shot manifolds on JP Norton
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DevonNorton
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Agree re the angle.
Just an observation but the first pic looks to be of Amal Concentrics - I know from personal marshalling experience (Croxford, Silverstone, Woodcote, 1973) that the '73 JPNs ran concentrics. Both pics above are for '72 JPNs.
The 2nd pic looks to be of Amal GP carbs.
Andy
Just an observation but the first pic looks to be of Amal Concentrics - I know from personal marshalling experience (Croxford, Silverstone, Woodcote, 1973) that the '73 JPNs ran concentrics. Both pics above are for '72 JPNs.
The 2nd pic looks to be of Amal GP carbs.
Andy
johnm
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I asked Norman White years ago why they ran Concentrics and he said they started with GPs but went to concentrics because they were easier and didn't seem to give any less performance.
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How do the float bowls work on the Concentrics at that angle. I have TT's with a matchbox float, on a 650SS head on a 500 Dommi I am building, the TT's are a fire hazard! I would use Concentrics if I thought they would work, I am trying to avoid putting a bend in the (long) inlets.
cliffa
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I was wondering the same thing. I wonder if they fitted a remote float bowl ( or two)
johnm
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I have Mk1 concentrics on an SS head 500 Domi and featherbed frame. Engine installed straight up as normal. The concentrics are fine. Just set the normal fuel level at the main jet location. I have never had a leak problem.
lcrken
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This is a better picture of one of the 72 JPNs showing it with concentrics. It doesn't look like they were modified to use remote float bowls, but there could be one hiding in there. I've seen it done before.
And another one with the GP carbs
Ken
lcrken
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Some good history of the early JPNs by David Bernard.
72 Works JPN Norton (F750 class)
The blue and white JP Norton 1972 came about when Norton Team obtained some sponsorship from John Player Cigarettes (hence the “JP” Norton) in December 1971.
The Norton Team for 1972 consisted of Team Racing manager: Frank Perris, Foreman: John Mclaren, Drawing office: Basil Knight, Machinist: John Fox, Mechanic: Dave Ludwell (engines) and Reg Paynter (engines), Welding Robin Clist, Mechanic: Peter Pyket and apprentice Mike Davis. Also Accounts: Ernest Harper and Store Tony Lynas. Peter Williams was Franks right hand man as development engineer and number one rider - unusual in motorcycle racing. Norman White was responsible for the assembly and race preparation of Peter Williams F750 and Production bikes.
Frank Perris the racing team boss, decided to race at Daytona USA, in March 1972, and to pursue the UK Formula 750 events and “TransAtlantic” series. It was decided that a completely new machine was required if the team was to compete with the Tridents, and the new Jap machines that couldn’t yet handle. Peter knew the trusty Norton Commando motor would be down on power and wanted a new frame from the standard frames as used in the previous years proddie racers. But it was already December, and he had to come up with something fast.
Foreman John McLaren called the team together, and stated that if they wanted to make Daytona 200, the team would have to work 12 – 15 hour days, seven days a week. Could they do it? The team agreed to go for it and have two bikes ready for Daytona in March.
During this period there was a coal strike when industry was only allowed to use electricity for a few hours a day. “We found a local fairground bloke who used to come with his bus and a great big generator and park it outside the workshop all day while he and his son sat round our coke stove and drank tea. It saved the day for us and kept out tight schedule alive”.
The bike Peter designed in many ways was to be a “mini-version” of the Doc Bauer / Bob Trigg designed road-going Commando frame. The top tubes were lowered to meet the steering head at the bottom instead of the top like the Commando. This had the effect of lowering the entire front end. The tank was low, and carried petrol in side tanks that sat alongside the cylinder heads, thereby lowering the centre of gravity to help handling. The motor was basic NVPS Production racer as used the previous couple of years in the Production racing “Norvil” or “yellow Peril, but had open exhausts and Amal GP carburettors. The petrol pump worked off a pump activated by the upwards / downwards movement of the swinging arm like the earlier works Matchlesses.
Within six weeks the prototype was ready for the mid-January launch at a London Hotel. Two bikes were prepared for Daytona: one for Peter Williams and the other for Phil Read. Whilst at Daytona the carbs played up, and the motors overheated because of the humid conditions encountered in the USA – the testing had been carried out in the UK hurriedly during a wet winter! The overheating was overcome by the fitting of car oil cooler from a Chevrolet Corvair which fitted neatly into the rear of the seat hump.
The Nortons qualified with Read at 102.152 mph, and Williams at 102.008 mph. Reads Norton passed through the timing lights at 152.54 mph. The first bikes home on race day were the new Yamaha 350s. The debut performance of the new bikes was encouraging with Phil Read being the first 750 home on a Norton in 4th place, but Peter went out with a gearbox failure - which was to plague them during 72.
After Daytona, the engine cowling designed to flow cool air through the engine and above the engine to the carbs (a forerunner to the modern airboxes) was discarded and the GP carbs were also replaced with Amal Concentrics.
Dave Croxford was signed as back-up rider for Peter in straight production machine events. Tony Rutter joined the team for the Transatlantic Match races at Brands, Mallory and Oulton, but didn’t stay on. John Cooper was drafted in for the TT, and Mick Grant was drafted in later in the season. By the time the TT came round in June, Norton had three reasonably competitive machines, and three potential race winners in Williams, Read and Grant. But the TT was not a success in 72. During practice the Norton’s hit persistent gearbox problems. The problem was that the clutch was about two inches from the gearbox main baring so the lengthy main shaft tended to flex. The resulting misalignment was transmitted through to the gearbox with detrimental results to the meshing between main shaft and layshaft dogs. The result that either the shaft or the gears in the box broke under load - there was simply too much horsepower for the old Norton box design. A number of variations of clutch size and cush drives were tried without initial success.
Norman recalls “ by the end of the TT in a desperate attempt to overcome the gear box problems, we fitted cush drives to the JPs Manx rear wheels, by reversing the hub, and bolting the six segment cush assembly to the small diameter side of the hub (the opposite side to the normal sprocket side). In the F750 race itself the problems struck again putting all three riders out – Read and Grant on the first lap, and Williams on the second.
Back in the UK, the bikes went really well – when the gearboxes weren’t breaking. The Norton team went to the big Hutchison 100 (raced the “wrong way” at Brands Hatch.) Peter won, and Phil Read beat Paul Smart on his Ducati, and a few weeks later Peter had some good battles with the fastest Truimph triples at Snetterton.
Jodi Nicholas raced at Silverstone that year – but he retired with a broken gearbox – the end result at Silverstone was three broken cylinder barrels and two broken gearboxes. Not a good weekend. However shortly later Phil Read won the “Evening News” Race of the South. So mixed results in 1972.
Norman recalls “ In the end it was Peter who figured out to resolve the flexing shafts. He designed a form of outrigger bearing that fitted in between the primary sprocket to the rear wheel and the clutch. He designed a new primary case and in its outer casting was able to put the bearing which supported the shaft. It worked, and the design was kept throughout the rest of the JPN series. By the end of the season the 72 bikes had the two in one exhausts replaced with twin exhausts, and the oil cooler was repositioned in the front of the machine with a small slot in the front of the fairing, feeding a channel connected to the cooler”.
By the end of 72 Peter was already working on some ideas he had for an all new design – a monocoque Norton. 1972 had been good when the gearboxes held together. With the gearbox sorted, could 1973 be the year of the Norton?
Thanks to Norman White for assistance for this article.
David Bernard.
The 72 JPN “works” Nortons were raced at:
12 March Daytona USA
31 March Brands Hatch: Anglo American series
2 April Mallory Park
3 April Oulton Park
?? April Imola
?? May Cadwell Park
?? May Brands Hatch
7 June Isle of Man 750 TT
The 1972 ex-Phil Read bike was sold in 1975 by Frank Perris (JPN team manager) to Dutch dealer Bas van Asten who kept it in his showroom, until purchased by Willem Koppejan of Holland. In October 2000 the bike was auctioned at the Brooks auction at Stafford and purchased by the Birmingham National Motorcycle Museum. The bike was partially destroyed in the Birmingham Motorcycle museum fire; was rebuilt / restored by Norman White Norton, and is now on permanent display at the musuem.
Ken
72 Works JPN Norton (F750 class)
The blue and white JP Norton 1972 came about when Norton Team obtained some sponsorship from John Player Cigarettes (hence the “JP” Norton) in December 1971.
The Norton Team for 1972 consisted of Team Racing manager: Frank Perris, Foreman: John Mclaren, Drawing office: Basil Knight, Machinist: John Fox, Mechanic: Dave Ludwell (engines) and Reg Paynter (engines), Welding Robin Clist, Mechanic: Peter Pyket and apprentice Mike Davis. Also Accounts: Ernest Harper and Store Tony Lynas. Peter Williams was Franks right hand man as development engineer and number one rider - unusual in motorcycle racing. Norman White was responsible for the assembly and race preparation of Peter Williams F750 and Production bikes.
Frank Perris the racing team boss, decided to race at Daytona USA, in March 1972, and to pursue the UK Formula 750 events and “TransAtlantic” series. It was decided that a completely new machine was required if the team was to compete with the Tridents, and the new Jap machines that couldn’t yet handle. Peter knew the trusty Norton Commando motor would be down on power and wanted a new frame from the standard frames as used in the previous years proddie racers. But it was already December, and he had to come up with something fast.
Foreman John McLaren called the team together, and stated that if they wanted to make Daytona 200, the team would have to work 12 – 15 hour days, seven days a week. Could they do it? The team agreed to go for it and have two bikes ready for Daytona in March.
During this period there was a coal strike when industry was only allowed to use electricity for a few hours a day. “We found a local fairground bloke who used to come with his bus and a great big generator and park it outside the workshop all day while he and his son sat round our coke stove and drank tea. It saved the day for us and kept out tight schedule alive”.
The bike Peter designed in many ways was to be a “mini-version” of the Doc Bauer / Bob Trigg designed road-going Commando frame. The top tubes were lowered to meet the steering head at the bottom instead of the top like the Commando. This had the effect of lowering the entire front end. The tank was low, and carried petrol in side tanks that sat alongside the cylinder heads, thereby lowering the centre of gravity to help handling. The motor was basic NVPS Production racer as used the previous couple of years in the Production racing “Norvil” or “yellow Peril, but had open exhausts and Amal GP carburettors. The petrol pump worked off a pump activated by the upwards / downwards movement of the swinging arm like the earlier works Matchlesses.
Within six weeks the prototype was ready for the mid-January launch at a London Hotel. Two bikes were prepared for Daytona: one for Peter Williams and the other for Phil Read. Whilst at Daytona the carbs played up, and the motors overheated because of the humid conditions encountered in the USA – the testing had been carried out in the UK hurriedly during a wet winter! The overheating was overcome by the fitting of car oil cooler from a Chevrolet Corvair which fitted neatly into the rear of the seat hump.
The Nortons qualified with Read at 102.152 mph, and Williams at 102.008 mph. Reads Norton passed through the timing lights at 152.54 mph. The first bikes home on race day were the new Yamaha 350s. The debut performance of the new bikes was encouraging with Phil Read being the first 750 home on a Norton in 4th place, but Peter went out with a gearbox failure - which was to plague them during 72.
After Daytona, the engine cowling designed to flow cool air through the engine and above the engine to the carbs (a forerunner to the modern airboxes) was discarded and the GP carbs were also replaced with Amal Concentrics.
Dave Croxford was signed as back-up rider for Peter in straight production machine events. Tony Rutter joined the team for the Transatlantic Match races at Brands, Mallory and Oulton, but didn’t stay on. John Cooper was drafted in for the TT, and Mick Grant was drafted in later in the season. By the time the TT came round in June, Norton had three reasonably competitive machines, and three potential race winners in Williams, Read and Grant. But the TT was not a success in 72. During practice the Norton’s hit persistent gearbox problems. The problem was that the clutch was about two inches from the gearbox main baring so the lengthy main shaft tended to flex. The resulting misalignment was transmitted through to the gearbox with detrimental results to the meshing between main shaft and layshaft dogs. The result that either the shaft or the gears in the box broke under load - there was simply too much horsepower for the old Norton box design. A number of variations of clutch size and cush drives were tried without initial success.
Norman recalls “ by the end of the TT in a desperate attempt to overcome the gear box problems, we fitted cush drives to the JPs Manx rear wheels, by reversing the hub, and bolting the six segment cush assembly to the small diameter side of the hub (the opposite side to the normal sprocket side). In the F750 race itself the problems struck again putting all three riders out – Read and Grant on the first lap, and Williams on the second.
Back in the UK, the bikes went really well – when the gearboxes weren’t breaking. The Norton team went to the big Hutchison 100 (raced the “wrong way” at Brands Hatch.) Peter won, and Phil Read beat Paul Smart on his Ducati, and a few weeks later Peter had some good battles with the fastest Truimph triples at Snetterton.
Jodi Nicholas raced at Silverstone that year – but he retired with a broken gearbox – the end result at Silverstone was three broken cylinder barrels and two broken gearboxes. Not a good weekend. However shortly later Phil Read won the “Evening News” Race of the South. So mixed results in 1972.
Norman recalls “ In the end it was Peter who figured out to resolve the flexing shafts. He designed a form of outrigger bearing that fitted in between the primary sprocket to the rear wheel and the clutch. He designed a new primary case and in its outer casting was able to put the bearing which supported the shaft. It worked, and the design was kept throughout the rest of the JPN series. By the end of the season the 72 bikes had the two in one exhausts replaced with twin exhausts, and the oil cooler was repositioned in the front of the machine with a small slot in the front of the fairing, feeding a channel connected to the cooler”.
By the end of 72 Peter was already working on some ideas he had for an all new design – a monocoque Norton. 1972 had been good when the gearboxes held together. With the gearbox sorted, could 1973 be the year of the Norton?
Thanks to Norman White for assistance for this article.
David Bernard.
The 72 JPN “works” Nortons were raced at:
12 March Daytona USA
31 March Brands Hatch: Anglo American series
2 April Mallory Park
3 April Oulton Park
?? April Imola
?? May Cadwell Park
?? May Brands Hatch
7 June Isle of Man 750 TT
The 1972 ex-Phil Read bike was sold in 1975 by Frank Perris (JPN team manager) to Dutch dealer Bas van Asten who kept it in his showroom, until purchased by Willem Koppejan of Holland. In October 2000 the bike was auctioned at the Brooks auction at Stafford and purchased by the Birmingham National Motorcycle Museum. The bike was partially destroyed in the Birmingham Motorcycle museum fire; was rebuilt / restored by Norman White Norton, and is now on permanent display at the musuem.
Ken
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I had the same problem of the gearbox shafts flexing when making good power. It was so bad that the gears were actually wearing on an angle. So I welded a reinforcing plate to the cases with a connection that extended to an outrigger bearing and that cured it.
DevonNorton
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Thanks to Ken for posting the detailed JPN info.
Concerning the '72 JPNs they definitely raced at many more UK meetings that year, e.g. at Mallory Park, Oliver's Mount and later in the year at Brands Hatch.
I saw them at the Snetterton 'Race of Aces' Meeting on 27th August '72 when Peter Williams finished 3rd behind John Cooper (BSA 750 triple) and winner Giacocmo Agostini (MV500 triple).
In those days the track included the long (nearly a mile) Norwich Straight so the Norton would have struggled a bit to keep up.
The race programme is on my friend Dave Riley's excellent website here: https://daveriley.weebly.com/uploads/4/8/4/5/4845046/snetterton-raceofaces-1972-plus.pdf
Here is a photo by Hayden Williams of the bikes at Oliver's Mount. Mick Grant leading Peter Williams and Phil Read. A 'home' circuit for Mick Grant. The JPNs are followed by Ray Pickrell and Percy Tait on Triumph Triples.
Good memories.
If I have time I'll try and fill in other 1972 UK dates.
Andy
Concerning the '72 JPNs they definitely raced at many more UK meetings that year, e.g. at Mallory Park, Oliver's Mount and later in the year at Brands Hatch.
I saw them at the Snetterton 'Race of Aces' Meeting on 27th August '72 when Peter Williams finished 3rd behind John Cooper (BSA 750 triple) and winner Giacocmo Agostini (MV500 triple).
In those days the track included the long (nearly a mile) Norwich Straight so the Norton would have struggled a bit to keep up.
The race programme is on my friend Dave Riley's excellent website here: https://daveriley.weebly.com/uploads/4/8/4/5/4845046/snetterton-raceofaces-1972-plus.pdf
Here is a photo by Hayden Williams of the bikes at Oliver's Mount. Mick Grant leading Peter Williams and Phil Read. A 'home' circuit for Mick Grant. The JPNs are followed by Ray Pickrell and Percy Tait on Triumph Triples.
Good memories.
If I have time I'll try and fill in other 1972 UK dates.
Andy
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Thanks for the info johnm, the engine is in a Seeley Mk4 so not straight up. I have some concentrics I can rob off another bike so will play around as it obviously can be done (also a pair of Keihin CR’s in a drawer somewhere
).
lcrken
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This picture, although kind of fuzzy, shows the Quantel Cosworth Norton fitted with MK2 Concentrics modified to use matchbox remote float bowls. I remember seeing them and thinking how clever that was. The seemed to work quite well, although Quantel eventually switched to fuel injection.
An even better picture from Brands Hatch showing more details.
Ken
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DevonNorton
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Thanks Ken. I never get bored of anything to do with JPNs.
I've told the story before but in 1973 I was marshalling at Woodcote when Dave Croxford had his famous 'off'.
I little lad from from the crowd came over to me and said, 'Do you want these mister?' and handed me a pair of Mk1 Concentrics with velocity stacks and cables attached. These went in the pick-up van with the rest of the monocoque JPN in 'kit form'.
The carbs had been launched over the crowd fence which would have been over 10 feet above track level.
Just great memories of fast races at Silverstone and a very lucky Dave Croxford.
Andy
I've told the story before but in 1973 I was marshalling at Woodcote when Dave Croxford had his famous 'off'.
I little lad from from the crowd came over to me and said, 'Do you want these mister?' and handed me a pair of Mk1 Concentrics with velocity stacks and cables attached. These went in the pick-up van with the rest of the monocoque JPN in 'kit form'.
The carbs had been launched over the crowd fence which would have been over 10 feet above track level.
Just great memories of fast races at Silverstone and a very lucky Dave Croxford.
Andy
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