Old Soldier

-SG- Every now and then we hear from Juris on progress with his 1917 WW1 Big Four - known as 'Old Soldier!' Recently he has been working on the silencer and his texts and photos follow on:

"We have made good progress on the exhaust system of the old soldier. Had to order 3 metres of thin wall pipe 32 mm in dia for the straight exhaust pipe from the UK as our local suppliers said that they cannot import thin wall tubes for fear of smashing them in transport. Have made tooling and pressed those silencer end caps on our hydraulic press. Please see the photos. They came out reasonably well. The good news is that I also need them for the 1927 model 17C and for my 1927 french "Monet Goyon" 4rc4 — racer with  350 cc Villiers 2-stroke engine. This bike has huge baloon tyres and I had only one option for replacements — to buy clincher automobile tyres and I need to cut more grooves in them to make them suitable for a motorcycle. I used Trimagard black phosphating paint from Trimite ltd and put the parts in a stove at 130 degrees for 1/2 hour. thus the semi-matt finish is weatherproof and will not rust."

Old soldier valves and seats - 1917 Big Four

-SG- Juris in Latvia has one of the very few surviving Big Four Nortons supplied to the Imperial Army in Russia in World War 1, and this  machine - nick-named 'Old Soldier'- has been mentioned on the site before. He has recently turned his attention to the cylinder barrel/valves. The barrel has minimal wear and the original piston is also very usable. But here's what he says about the valves ...

"I removed the valves and was surprised to find their stems to be double diameter - 3/8” near the head and 5/16” for about 3/4 of the stem length. Interestingly the worn exhaust valve guide had been sleeved with a bronze sleeve sometime in the '20s or '30s, many years before bronze valve guide sleeves were invented! The valve seats in the head look like they have never been cut, only lapped in with paste. Their width is now around 4 mm. I will put in chrome-moly valve seats as I do not want the hassle of regularly grinding in valves with paste— just have not got the time and of course these will not be conspicuous from outside.

I intend to retain the existing valve guides and to machine them out and hone to 3/8” throughout to accept modern chromed stem valves from Caterpillar and Mack trucks. I have no idea if these valve guides are original or they have been changed at some point in time. I have a feeling that they may be original. The truck valves are very tough and they should last another century."

While the threaded valve guides looked original, the valves did not and Juris also mentioned that they appeared to have been made from larger valves with the slots hand filed.  But … the threaded valve guides were not something I had come across in my limited exposure to earlier Norton design details. So Juris did some more checking and found the guides were in fact threaded the same as an 18mm sparking plug and better still, that they were the same as those on another WW1 Big Four rescued from Russia several years back (via Finland!). I am told that, at this period, Nortons used 5/16 stem valves and press-in valve guides, so perhaps the threaded guides were a nicety provided on the Military Models to aid service in the field.

postscript - Andrew in Australia has dropped us an email about Veteran Norton valve guides, for which thanks.  He writes: 'Both my 1910 cylinders and my 1911 cylinder have screw-in valve guides, and a 1908 one here has the same cylinder as the 1910 type so that would be the same!   More info for the melting pot!

1917 Big Four Norton

-SG- Juris Ramba in Latvia is in the throes of rebuilding a First World War Big Four Norton which he obtained from Moscow just a few years back. It's source rather disproves the official records (Government) which apparently show no Nortons being sent to Russia at the time. However, the photos of the engine internals are interesting and show how little the general design changed during the twenties. It is thought that the two figures on the end of the engine number indicate the year of production - ie 1917 and that the M/M in the engine number supposedly equals Military Model; but if anyone has any other suggestions, let's be having them! The crankpin incidentally is of the plain bronze bush type and mainshafts supporting the extremely heavy flywheels are the usual Norton size of the time - 22mm.