classic motorcycle forum

As far as I'm aware for a time prewar Ariel used the letters RH on the timing case to show a particular model was from the sporting VH, LH or NH Red Hunter range. The numbers 250 and 500 refer to engine size.  As you can imagine swapping the standard timing case for an RH one was a sneaky way of claiming you had a top of the range bike and not the bread and butter version or impressing everyone with your really fast 250 which was really a 350.
You get the picture. Having an RH outer timing case fitted is no guarantee as to what the engine is. Given the easy interchangeability of Ariel parts the only way you can do that is to strip it down and check. For example you can't see what type of main bearings are fitted without pulling the flywheels out and Ariel made a point of specifying a heavier duty bearing for the Red Hunter than they did for the standard engine.
All of the above makes discussing your engine rather vague as we don't really know what it is. Not that this matters much as I'm sure you'll have fun with the finished article and as it won't be ridden fast and far it should hang together okay.

It's all about the power/weight ratio. You can either add power or reduce weight for the same performance increase. Reducing weight is by far the cheaper option and makes for a more agile, responsive and better handling bike.
Before I even thought about engine modifications I'd be making sure the frame and forks were straight and working how they should plus the wheels balanced, brakes not binding, chain sprockets in line, etc so rolling resistance is absolutely at a minimum. After that comes the weight reduction program.
About the only thing I'd automatically do to the engine of a girder fork Ariel is fit a big bore oil pump. Ariels slowly increased the oil pump bore over the life of their singles and I'd make sure I had the last and biggest size fitted. Its a standard part and just replaces the earlier ones. No drama.
Cheers,

As R says, it is all RE's own work. No using bought in engines for Royal Enfield but of course being Australia there is a twist to it as your particular Royal Enfield model was rebadged and sold out here as the Cottman Colt.
Cottmans were an active dealership here in Melbourne and for some reason sold the RE Model A rebadged under their own name from the mid-30's until Hitler stopped play.
RE never resumed production of the Model A postwar instead concentrating on the 125cc Flying Flea as their preferred two-stroke model.
There is at least one surviving and well restored Cottman Colt in Victoria that runs quite well although I haven't seen the elderly restorer on it for some time.
So, do you have a Royal Enfield Model A or a Cottman Colt?
Cheers,

Of course the drum brakes on any classic bike aren't as good as disc brakes on a modern bike. Disc brakes were introduced to improve braking performance and a good thing too but that doesn't mean drums are no good. They are just different and the rider has to change their riding habits to suit the abilities of the brakes in question just as they also have to change to suit the old fashioned engine characteristics. Isn't that one of the reasons riders go classic? Riding a classic requires much more thought and input from the rider to ride smoothly and well but the increased grin factor and riding satisfaction makes it all worth while. Isn't that why we do it?

It is also quite possible to get quite reasonable performance out of drum brakes including the B31 brake which to my mind is no different from anything else from the period. There are various little tweaks applicable to them all.

Finally, it doesn't matter that it's a B31 in question, 90% of us would disagree with whatever you had in mind. That is just normal motorcycle stuff. We all think we've got the right bike and anything else is wrong. Go ahead and buy your B31, mate. You'll have a lot of fun but in a few years you'll be looking around thinking "I wonder what a Velo, or an Ariel, or a Matchless (or whatever) would be like?" You'll be like the rest of us and just want to try them all.
Cheers,

The Series I was 1947 only. It had a single down tube frame and was not of the cradle type but instead had an open bottom section with the engine supported on engine plates.
The Series II was 1948 and also powered by the 5E. It had a different single down tube cradle type frame but posssibly with a detachable lower frame section.
Then of course we get the Series III for 1949 & 50 with a proper single down tube cradle frame and the 6E engine.
Ambassador never used a twin down tube frame. To answer your query I've just ploughed through "A Guide to Ambassador Motor Cycles" by Michael Easton and Fred Hibbert which lists(with pictures) every model of Ambassador made. Sorry, no twin down tubes.
Many makes of British lightweight used Webb pressed steel girder forks, from the early 30's through to the early 50's but offhand I can't think of anyone using a twin down tube frame. Can we have a photo?
Cheers,

The 'kit' bike thing certainly worked in the 20's and 30's. The Waratah was basically a Sun-Villiers kit plus there were others like the Utility and Simplex, all Villiers powered. About the last was the Acme, introduced in 1939 and carrying on into the 40's finally stopping when Villiers stopped making the 9D engine.
Generally though these bikes were a unique assembly using their own frame numbers even though they were just a different way of assembling the standard British lightweight jigsaw puzzle.
These postwar bikes are different. There is no doubt they are Norman or Excelsior because they retain the Norman and Excelsior identifying numbers and they appear to have no local content. There is no attempt to disguise them as anything other than what they are-except for the transfer on the tank.
Finally, I've never seen either a Roamer or Rambler tank transfer. I have the Roamer info in my Police Records and have seen an old painted 'Roamer Agent' sign on an abandoned motorcycle shop in the country but nothing more.
It's just another of those odd little motorcycle mysteries I suppose.
Cheers,

You'll notice the owner calls it a display bike. He carefully avoids any mention of it even being a runner let alone ever actually seeing a race track or being entered in a race.
I think it's just someone having fun building a showboat but not a riding bike.
Cheers,

Norman were sold in Australia under both Norman or Roamer brand names (not Rambler) although there are stories they were sold in other countries as Ramblers. It was just badge engineering like Matchless/AJS. Exactly the same bike even to frame & engine numbers but different tank transfers.
If it has the original engine the number will start with the prefix 364/, the frame prefix is B/ as you show.
Norman/Roamer first arrived here in 1948 and as that was the last year of the 9D engine (the 10D appeared in 1949) I would say its pretty conclusive you have a 1948 Norman/Roamer.
The above info comes courtesy of my copy of Victoria Police Complete List of Motor Vehicles, Data for Registration Purposes.
The VMCC Library ( www.vmcc.net ) has a leaflet on the two bikes in the 1948 range and a broad range of Villiers info. They will happily sell photocopies to non-members. They can also supply all relevant Norman transfers but I think you'll find it difficult to find the Roamer equivalent as Roamer appears to be an overseas market name only.
Cheers,