Norton JAP
Some bikes defy any need for a clever or witty standfirst; this Norton JAP is one such creation
What if you wish for speedway thrills on the road? Build one, of course, with a Norton frame and JAP engine. And a saucepan.
Aconductor brings a number of elements together to create a harmonious, finished piece. I have specific instructions not to name the creator of this machine, so I will call them the Conductor, for they have done a similar job of bringing a number of elements together, creating such a harmonious machine.
With age comes experience, and with experience comes the inner strength to have what you want, how you want it. That could form from something you’ve seen, a dream you have or a memory... and so it is with this Norton JAP. Our Conductor started riding on an Ariel Arrow, or rather, three of them, all donating to keep one on the road. These would be added to bikes for playing with, costing a few quid, which would then be cut down, or bobbed, with all unnecessary parts removed.
There would often be a set of motocross handlebars added with a cross brace, then they’d be roared around wherever was, or was not, allowed. Being in the country, and especially summer and harvest time, there were no shortage of places to roar.
These creations would emulate racing machines. “Speedway up Norwich with the Stars, or Scrambles at Lyng was all we knew weren’t it,” explains our Conductor. And dozens of bikes throughout the years have followed this philosophy of building what you would like with what you have about you.
Decades later, and back to the bike you see here. The starting block was a rebuilt 500cc JAP 4B single cylinder engine, so often seen powering a speedway bike or even racing cars from many different decades since its inception in 1929. The 4B has larger inlet tracts to the preceding 4 and 4A versions, in case you wanted to know.
These are proper racing engines; no less than the Ford DFV, or Norton’s Manx unit, with a two-ring piston. Oil is total loss with an adjustable, doublechamber pilgrim pump delivering said black magic to the big end and to the rocker box, while none other than a saucepan (thanks, Steve) acts as a catch tank – literally – hanging below. Like an open-air sump.
To make it more road-friendly, this one has been built and superbly converted by Alan and Jamie Bellham, of Speedway Service Ltd (01553 829197), to run petrol instead of methanol, and a lower compression ratio, thanks to a sandwich block between the crankcases and the Alfin barrel.
With a different cam, and the large new Amal carb fitted and jetted appropriately, it weighs just four stone (25kg) and runs with the manners of a choir boy. “I could’ve had a Jawa for a lot less (money) with better reliability, but it’s no JAP.”
Next was to find a cycle with which to fit such a superb engine. “I always wanted a speedway bike but you can’t use them; tuned engines, silly low gearing and no gears... you don’t want a speedway engine to be on the road.” So the only way to get that feeling of a speedway bike was to put it into a road frame with a gearbox, “and the only frame that sounded right to me was a Norton rigid”.
“The JAP engines look so old, but so good. So I went looking for a frame that would suit the engine. I wasn’t fussy; I first found a Triumph rigid (a 5H) but it was almost complete and, once I’d had a look, certainly too good to muck up. It even had a good engine. So I stopped and did that up to put back on the road first. That goes better than I thought, especially with sidecar gearing.” We’ll keep that delight for another day.
Triumph excursion aside, a rigid Norton frame became the ideal solution for a variety of reasons. Then, by chance, a Norton 16H frame cropped up: “It was in good condition and I had some Norton hubs laying around, so I thought that’ll do.” That’ll do. Presumably you measured the JAP in all dimensions and saw that it fitted into the 16H all right? After all, the 16H is a sidevalve engine and the JAP an overhead valve and therefore taller? “Well, it looked about right and the sidevalve frame isn’t too different to the Norton overhead valve frame (like the ES2, Model 18 and Model 50).” I suppose that is true. And there was no choice, as “I didn’t want to alter the frame because if I wanted to, I could just stick a
Norton engine in it”. Did it have to be a rigid frame? “A swinging arm frame is much easier to ride, but they don’t look right. It had to be a rigid in my eyes.” Did you ever think about making your own frame? “No, it’s too much hassle and when something’s right, that’s right, and the Norton frame was right.”
Another reason for the Norton frame, apart from that heritage, was the want for a doll’s head Norton gearbox. “I’d always wanted a Norton with a doll’s head gearbox, but could never afford one. And that got me thinking how all the clutch actuator and so many parts of the doll’s head are outside, and it would look good with a JAP.” This oft-used ‘box has its own charm and look – a look our Conductor thought would marry well with the upright stance of the JAP engine. It also fits perfectly in the frame, having been the ‘box the frame was designed for.
The doll’s head gearbox was constructed from a collection of parts, built up from many years of bartering, autojumbles and collecting. But some parts were still needed, and our man couldn’t work out exactly how it worked. So a friend kindly loaned a complete doll’s head ‘box, so the way it goes together and works was easier to understand. Norton specialist Norvil and eBay helped with the missing parts, which finished the hardened-steel jigsaw.
With a rebuilt gearbox and a fully-built engine ready to work together in the frame, engine plates needed to be sought. “I got some back plates and the standard gearbox plates, then I got some standard
16H plates made up with an inch more ‘meat’ on the engine side so I could profile for the crankcases.
“Because the engine needed an oil catch tank, I tried to get the engine as high as possible, then making the front plates.” Did you use cardboard to make the templates? “I did, but I couldn’t weld it so I used 4mm steel….”
To get the gearbox and engine to mate, an offset belt pulley was made and moved the clutch in a bit on the gearbox mainshaft to get them lined up... then the Bob Newby belt drive worked perfectly.
The tank is another find, although no one is sure what it’s from. The closest photograph found is from a 1930 two-stroke Royal Enfield with two filler caps for the two tanks and a speedo in the top.
“The tank is another find, although no one is sure what it’s from. The closest photograph found is from a 1930 two-stroke Royal Enfield with two filler caps for the two tanks and a speedo in the top.”
“I’ve put a rev counter in there and I like the profile. That came from my old friend Roger Loye years ago. He was a good old boy and was very clever, building and restoring bikes. I can’t build bikes with paint on ‘em, but he would assemble a bike, get it right, then strip it, get it painted and build it up again. We lost him years ago.”
The Norton early rear hub was laced with a hub from Devon rims, who offered two types: a perfect one, or one with a few scratches. “I like to use my bikes so a few scratches don’t worry me, but when it came I couldn’t see anything wrong. At the front is the wheel from my Norton 500T replica, which has a small 6in Ariel hub on a 21in rim. I had the bike sitting next to it, wondering what wheel size to use, when I thought, that’ll do.”
The Brampton forks are another unknown; found from a friend, who sold them to another friend who didn’t use them due to looking so small. “They are Brampton double diamond – the front tube goes straight down and the back one kicks in a bit. But they are possibly racing ones – I’ve seen them in obscure bikes, like Grindley Peerless and other ‘odd’ bikes.
“They pitch forward a decent way, and give good rake for stability. But they suit the light engine well and were easy to fit. They’d been in a Harley 45 frame and someone had made a solid stem but that was too short and made another from an old BSA steering
stem and a couple of spacers, making an old top clamp up with Norton head races, but the base had to be turned down on the lathe. That went together well. Those bars were Norton straights, but I ended up with Thunderbird ones. They feel about right.”
The exhaust is all speedway and sounds wonderful, if unusually conservative for the Conductor’s machines... cacophony would normally be a better term. Tyres are Pirelli trials items, while the seat is another ‘hanging around’ part. Since the photos were taken, a front mudguard has been fitted, together with a lovely aluminium belt drive and a kink in the down pipe to lift the silencer. “Even with the folding footrests (re-jigged Norton items) it was draggin’ on right-handers.”
Most noticeably, the saucepan has been retired, since Alan fitted a return pump they use mostly on Jawa engines. No more pouring Rock oil castor oil in like it’s petrol.
It rides well, once I’ve got it started, which can be a couple of kicks. It’s light off the rear stand and, for a one-off, all the controls feel to hand. It’s built for large work boots – don a pair and the gear lever and footrests make sense... though Maria had a go and size 5 feet didn’t feel quite at home!
After 20 or so miles, the plug oils up – the pump needs adjusting to feed less oil to the top – and you needed to check the oil level before the new pump was fitted. But it’s quick and the lack of inertia from the competition engine gives an instant response.
It handles well for a special – predictable and brings confidence; and when tarmac turns to dirt track, you can dive straight down.
“I went running around the lanes and through the floods yest’y and it was lumpin’ and bangin’. It’s not ideal off-road on the bumps, but that’s all right on a muddy track. If you’re going slow – I was following a van – it feels a bit ‘weavy’. But riding fast it feels good. Like my Land Rover, the faster you go, the better it handles.”
The small competition engine looks tall, but this is largely due to the narrow fins playing with your eyes. And that gearbox fits perfectly. The Conductor’s style is quite unique, but it also makes the bike useable – there’s rarely a time you can’t, or daren’t use the bike.
Is it everyone’s cup of tea? Absolutely not. The Triumph Terrys will simply not understand it. The Vincent Vinnies will look down their noses. The Gold Star Grahams will continue arguing whether it’s better to have a STD or RRT2 gearbox.
But they will be intrigued. This tatty-looking, industrial-esque Norton JAP has a charm that is hard to fathom and impossible to ignore. It is the epitome of what nowadays is often called ‘patina’. It belongs to no genre; the workmanship cannot be admired nor criticised, and few know the provenance of this superbly successful racing engine.
As a machine that does what its creator wished and looks like how they wanted it to, it is perfection. A composer creates, but a conductor brings a masterpiece to life.