Roadster to Interstate

The S-type had a high level exhaust with both pipes down the left of the bike. They were produced in 1970 mainly for the US market. You'll find some pictures in Roy Bacon's "Norton Twins". If you do a search here you'll find information about frame / engine numbers versus year. On a 50 year-old bike I wouldn't count on anything you see being the way it left the factory.

The basic differences between Interstate and Roadster were tank / seat / side panels.

As for recommisioning a bike that hasn't been run for 8 years, well, all the usual suspects. You've done old brits before so it's down to you to decide whether to just do a major service and fire it up or do a partial strip down first.

Looks like a '71 Roadster to me. Who told you it was an S-type?

Apart from the comedy seat, high bars, hacked off rear mudguard and rear light assembly it looks pretty standard and complete. The air cleaner's gone but that's very common. The paint, well someone, somewhere must like it. Exhaust looks to have been replaced but most original silencers rotted out years ago. Fork stanchions look like they need some attention.

It has the cush drive rear wheel and the late fork yokes, so I'm suprised it doesn't have a disc brake.

I'd change the oils, clean the carbs, check the valves and compression, check the ignition timing, squirt some oil down the pushrod tunnels and fire it up.

Hi,

Maybe 1st check the VIN to see if it is an S code. If it's an "S", Value wise would probably be better to return it to something near original than convert to an interstate.

Either way, personally I think it looks way cool the way it is. I've got a nice shiny 73 but I'm jealous!

Eddie

My understanding is that the "S" in the 20M3S engine number prefix indicates a 750 with points on the end of the camshaft + some other minor changes to the engine.

Interesting that your front mudguard looks different from the left and right :)

+1 to Eddie Cross' suggestion that you leave it as a Roadster - unless you're planning long trips it's by far the nicer version.

I think you have to accept that it's a standard '71 750 Roadster that some misguided person has, errr, modified. With luck, they will have restricted their efforts to parts that can easily be replaced.

I always liked the original metal flake fibreglass finishes; much bigger flakes than standard metallic paints. And there's the added advantage that they weren't pin-striped which is hard to get done well these days. You can continue using a GRP tank if you can be bothered with the hassle around ethanol-doped petrol.

... the roadster side panels to the Interstate ones, even if the rest is Interstate.

I can see Ian's point about the side panels but my view is that smaller panels make the tank look larger than it is. Interstate side panels as original are unlined which makes them look too large. Interstate panels cover up some of the frame and can hide discreet modifications.  Additionally, there are two Interstate tanks, a large, wide, flat one and a slightly taller smaller one.  From memory I think the very large one holds 29 litres of fuel. The one problem with the very large one is that if it is full it can be very tricky to take it off the machine.  Having had an interstate version for over 30 years I now have a Roadster and would only convert back for touring. I can't imagine that there are many other machines that you can change from 2 & 3/4 gallons to 5 & 1/4 in half an hour, providing that you have the alternative seat and panels too. I think the handling is improved with the Roadster tank because the rider is further forward. And, as any long-term Interstate owner will tell you, the machine handles much better when the tank is nearly empty.