1928 Norton CS1

The CS1 (Camshaft Senior 1) was Norton’s very first overhead cam engine. Introduced for the TT in 1927 they went on sale to the public later that year as race replicas. They continued in this guise, along with the 350cc CJ1 (Camshaft Junior 1) for a couple of years before its designer, Walter Moore, left Norton to go to NSU and took the design with him. He owned the patent as he’d done all the design work in his own time. This happened in 1929 and Norton brought Arthur Carroll in and tasked him with a complete redesign. The International was born, this turned into the Manx after the war and became the very successful racing bike we all know. More information on the International and details of our restoration of a 1934 model can be found here.

The CS1 continued, with a Carroll engine, until 1939 when it was dropped and never reintroduced after the war. The 30’s CS1’s where more of a softened version of the racing Inters than anything else. They had coil valve springs instead of hairpins, softer cams, lower compression and so on.

Without a doubt the Moore CS1, more commonly known as the Cricket Bat because of the distinctive shape of the timing chest, is the most desirable.

My CS1

Bought in 2017 from a friend who had owned it since 1982. This 1928 CS1 had been used by the previous owner for couple of years before being taken off the road as it needed a few jobs doing. Other events took over and it was never finished. He has decided now that it is too far down the list so it will never get done.

It is incredibly original, with the exception of the alloy mudguards and the Amal carb (it should have a 2 jet binks, so if anyone knows where there is one available please let us know) As such the decision has been made to re-commission rather than restore it to keep as much of the patina as possible.

Strip and Clean

The first job was to completely strip and clean the bike. This proved very time consuming and it’s not as easy when you want to preserve the original paint. You have to wash the dirt off whilst being careful not to lay into it and take paint as well.

Here’s the frame outside following a lot of time cleaning. First with a hoover to get all the loose saw dust off, then a hose to blast the worst of the dirt off, then de-greaser and a rag. Last job was to touch in the pain to stop the rust getting a hold.

Note the 3 stay frame - this was only used on the CS1 and ES2 and only for a couple of years. Quite a rarity now.

Crankcases

The crankcases were washed off in petrol and the oil ways blown through with an airline. All clean but worth checking. Fortunately this engine is very clean inside but if they have been run on Castrol R in the past this job can be a nightmare!

The main bearings are good, based on the history of the bike I suspect they are new. The gasket faces where cleaned up and the cases were ready to be re-assembled with some Wellseal. The bearings are packed with some Graphogen as well to ensure they are well lubricated on first start up and until the oil has made its way round. The Graphogen is then washed out and removed with the first oil change.

Bottom end re-assembly

The crank cases were re-assemble. The end float was checked and found to be correct. It should be 0 on a CS1 as any end float will cause problems with the meshing of the bevel gears.

The bevel gears where then re-assembled and checked for backlash, again found to be correct, and the plunger oil pump re-fitted. This was very early days of dry sump, re-circulating oil and the pump is so simple it seems amazing its efficient enough when compared to later models.

The bottom end of the engine had to be stripped for peace of mind, but went back together with nothing more than a clean up required

Cylinder Head

The cylinder head was tested for leakage and the exhaust valve found to be allowing a small amount of fluid to leak past the seat. The valve seat was re-cut and a new exhaust valve fitted. Other than this very minor issue, the engine was re-assembled with no further problems.

Girder Fork Repair

While the cylinder head was away having the new seat cut work on the rolling chassis carried on. The first task was the repair and re-fit the Heavyweight Webb forks fitted to the CS1. We have done a Girder Fork Repair page in our Technical section. So take a look there to see what was done.

Girder Fork Repairs

Wheels

The next job was to replace the badly worn rear wheel bearings. As the original cup and cone type are no longer available, the rear hub was skimmed out to take a modern day taper roller bearing. Not only are these readily available they should also last longer and make for easier adjustment and lower maintenance.

Fitment of modern bearings meant making a new wheel spindle, spacers and nuts. It also allowed for the inclusion of modern day nitrile oil seals.

Once finished and re-fitted to the frame, the back wheel has all the new bits hidden. Keeping the appearance of the bike as being original and untouched.

Gearbox

There was some rather major damage to the gearbox. A new layshaft, kickstart shaft and a host of other smaller parts were sourced.

We were able to source a new end casting from Ken McIntosh in New Zealand and machined it ourselves.

This was quite involved so we've given it a page of its own.

Exhaust

The bike came with a Brooklands can. Although a very nice original it wasn't correct for this bike. We set about manufacturing the correct Double Barrel Exhaust Silencer which we are now able to offer for sale in our shop.

The only difference between the one on this bike and the ones offered for sale is the tubes were painted matt black with a rattle can instead of stoved gloss black in order to tie in with the oily rag look.

Shop Here

The bike was finished in time for a 2018 ridding season and is now used regularly on day, weekend and week long vintage rallies. It has done several thousand miles now (a guess as there is no speedo) and other than a few teething troubles has proved very reliable. Here are a few pictures of it on a week long rally in Wales.