1951 Norton ES2
The ES2 was first introduced into the Norton range in 1928. It shared it's cycle parts with the CS1 but had an OHV engine and was made throughout it's existence with a more up to date specification to the Model 18. 1939 saw the introduction of plunger rear suspension as an optional extra but this was short lived as the ES2 was dropped from production during WW2. When re-introduced after the war, plunger rear suspension and telescopic Roadhoalder forks were standard. In 1948 the engine received a major redesign including and oil feed to the rocker box, stronger timing side crankcases and largely improved valve train. 1950 saw the of the Laydown gearbox. This reduced the travel on the lever which make for an easier box to use, but does nothing to limit the persistent oil leaks. The ES2 shown here is a 1951 Model so comes in the specification just mentioned. Later updates included a larger petrol tank, swinging arm rear suspension (pre-featherbed, wideline and slimline frames where all used), alloy cylinder heads and alternator/coil electrics to name a few.
My ES2
The ES2 was bought in 2013 to be used for regular trips away both in the UK and abroad. It was purchased in the condition seen here, so although fairly scruffy it was mostly complete. The main task was to strip, clean, repaint, chrome plate and reassemble. This was completed by early 2014. However, after a seasons riding, including a trip to France, it was decided that the performance wasn't what it should be.
Over the following years this bike has had a number of upgrades to make it more useable for long trips. This page will focus on these rather than the overhaul of a standard ES2.
Piston
The first task was to raise the compression ratio a bit. A standard ES2 is about 6.5:1, assuming everything is in good order. A 16H piston can be used to raise this to a around 8.5:1. The pisting needs shortening and valve pockets machining in. Here you can se a standard 16H piston and the one we modified for the ES2.
The 16H piston gives a nice dome to reduce the combustion chamber volume. We also use rubber O-rings to seal the oil returns. This is required after the the barrel and head where machined and ground together to remove the need for a head gasket. I minimal increase to compression but it does stop the head gasket from blowing, a common issue with currently available aluminium head
gaskets.
Why not take a look in our 'Technical' section for a page that goes into more detail on how we modify 16H pistons like we did for my bike.
Valve Timing
Further down the engine we’ve done some experimenting with different cams. Firstly we tried a set of race cams. The bike was used like this for a year or so and even on a 3000mile round trip to Italy and back. Regularly hitting 80mph the ES2 certainly flew, but it was difficult to ride and ‘lumpy’ in traffic so the cams were removed to try another option.
With some more experimenting we found that the ES2 had very lazy valve timing as standard so decided to go back to standard ES2 cams but advance the inlet cam one tooth to give lobe centres closer to what we thought would be optimum. This made a huge difference to the performance and the bike is considerably more enjoyable to ride!
Although much happier with the ES2 fitted with standard cams and altered valve timing we decided to see if we could take it a step further. We got hold of a set of 16H cams which are a straight swap but offer slightly more lift and duration, without being as extreme as the race cams.
To help fine tune the timing with these cams we had 2 extra keyways cut in a set of timing gears allowing us to set the valve timing in 6° increments instead of the 18° we are stuck with on a standard set up.
This set up gave a significant improvement, once the carburation had been set up to match it, and is still in the engine now.
To help compare some of the cams we have experimented with we have created a technical page on OHV Norton cams which includes a table showing a number of useful comparisons.
Front Forks
A common problem with the plunger Nortons is how they bounce about over bumpy roads. There isn't a lot you can do with the plunger units but damping the front effectively makes a big difference and stops the bike getting into a rhythm after hitting a bump.
We have fitted a set of later, Commando type, fork internals to offer better damping, they offer a significant improvement over the original fork internals.
However, there are a number of other options on the market now. We have fitted a set of RGM internals to a Model 18 since doing the ES2 and, if the time comes to change these, I think I would go for those next time.
Front Brake
Once the performance started improving it became apparent that the standard 7" brake wasn't up to the task. It worked brilliantly for about 20 yards, then got hot and faded to away to nothing. Not ideal when you’re still doing 40mph!
I found a slightly later 8” front brake on eBay, being a Norton brake designed to fit in the same forks it was a straight swap so, after building it into a new rim, it went straight in and this gave a marked improvement to the breaking.
Panniers
An important part of any touring bike, the panniers where bought with a rack to suite a modern Triumph. This was then modified to fit the ES2 frame whilst retaining the clips and fittings.
The panniers can be locked closed and locked to the bike, so the panniers offer a level of security for riding gear whilst out exploring the places you've stopped at!
This work was done in a bit of a rush before a rally and, after using the bike, I discovered the panniers were too far back. When fully loaded the bike started to weave at anything over about 50mph due to the lack of weight on the front wheel!
After putting up with it for several years by just not filling them up with anything too heavy, we cut the racks up again and managed to move them forward about 3.5", my heal just about clears the pannier now for starting with them on.
We took the opportunity to tuck them in as well and they are nearly 2" further in, making the bike 4" narrower with both panniers fitted. This was so tight that the right hand side pannier rubbed on the toolbox, rather than move it back out we moved the tool box in about 1/8" to regain some clearance.
The handling was transformed and it looks a lot neater as well. Win win!
Finishing Touches
I rarely ride the bike at night so the lights aren't a huge concern, but conversion to 12V makes fitting a Garmin satnav easier. An AO Services electronic regulator and an LED stop/tail light helps the standard Lucas dynamo keep up.
The bike handles considerably better on a set of Avon AM26 Roadriders than it did on the more classic tyre patterns I ran to begin with.
Although I still very much view this bike as an ongoing project, I am now very happy with it in it's current state. It has become my firm bike of choice for longer trips. I'm not entirely sure what is next but I'm confident it will continue to get better without losing it's classic bike appeal. I have now done over 13'000 miles on my ES2 in, amongst others; France, Germany, Switzerland, Italy, Austria and, of course, the UK.
