Discussion in 'Norton Commando Motorcycles (Classic)' started by VR880, Dec 13, 2005.
Does anyone know if a 530 O-ring chain will fit on the 74 850 Norton without modifications.
O-ring chains are too wide to fit. They rub on the trany and/or inner primary cover. Use a Renolds HD chain with a Scotts oiler and you'll be fine. 5000 miles plus.
If you want to run an o-ring chain, get a 1/4 inch gearbox sprocket, either one for an early Atlas or Dommie or one of the new ones from Old Britts or others. Next have the rear drum and sprocket milled to 1/4" on the teeth. Now you can run a 520 O-ring chain with no clearance problems. Alternatively, you can get all you need from Fred at Old Britts.
I had a nasty experience with 1/4-inch chains. The first two prototypes had them. When we were doing endurance testing at high speeds (100 mph for 10 hours, with just rider change-over and fuel every 2 hours) we were making chain adjustments at every other fuel stop (400 miles).
We had a chain failure on the banked tri-oval section of the test track at about 110 mph - turned the engine into a boat anchor! Valves were bent, piston cracked and separated through the wrist-pin bearing and a con rod out the side of the case. The tach needle was bent and had jumped past the high-end stop, as the engine was at full throttle when the chain let go. It may have hit 10,000 rpm before it came apart.
If you ride hard, I wouldn't recommend going down to 1/4 inch. You might want to consider an enclosed chaincase. I've seen two types. One is a sheet metal shroud, split down the centerline. The other was made up from 1" square aluminum tube with flex joints at the ends with the chain threaded through before the split link was closed. Some times people put oil in the bottom of the case, but mainly they keep road grit out of the chain bearings.
Modern 520 o-ring chains have a tensile strength of around 7500 lb, which should be more than enough for our old Nortons. If I'm not mistaken Derek Wilson has been riding his Commando with a 520 conversion for a couple of years now with no problems, and he puts a lot of miles on his bike.
Yes, chain technology has come a long way in the last twenty years. A modern 520 O-ring chain is plenty strong. My 900SS SP Ducati runs one and it makes considerably more power than most Nortons.
You're right, Ron. Materials and lubrication technologies have come a long way.
The failure we had was the split link. As best we could figure, the snap retainer failed, allowing the removable side-plate to separate. Tension in the chain then pulled the pins apart (about 20 degrees) by bending the fixed side-pate on the other side. The remains of the side-plate and pins were still in the end of the chain.
I think it might have been a combination of tension and fatigue that caused the initial failure. You Ducati is probably a lot smoother in its firing impulses than the Norton twin.
Most modern bikes, including the Ducatis, use a rivet-style master link, avoiding the problem of the clip coming off. Also, the side plate is usually a press fit on the o-ring and x-ring chains.
I'm planning to convert my Norton to a 520 x-ring chain and I think I'll use the rivet master link so I don't have to worry about it.
Final Drive Chain - again
Has anyone fitted a Regina 530RS chain? I just fitted one today and the clip type joining link seems to be too wide, just catching on the primary case. Tried reversing it but seems to catch the gearbox then. I could try the rivet type link which also came with it, but will need a bit of help with that so don't want to go to that bother if the overall chain proves to be a bit of a neat fit - so any previous experience appreciated. Previous chain was RK 50KS which worked fine.
I would talk to whoever i bought it from but it has been sitting on the shelf for a while and my fading memory won't recall where i got it.