rear hub question

I saw this bike on ebay and in one of the photo's it shows a removable rear sprocket. Was this an option or a custom modification? Item number 270682543601

That is custom built. I have built a couple similar by welding a ring to a stock drum and then machining and drill and tap. Not a real minor undertaking but a great mod. Jim

Jim, do you do this mod for people?

I can but it won't be cheaper than a new drum. Generally the only ones I have done were for people who were racing stock class and wanted to be able to change gearing at the track. It will limit the sprocket size to over 45 teeth and requires a custom sprocket also. Jim

1977-78 Suzuki GT750 Water Buffalo hub can provide cush drive, changeable sprocket and disc brake rotor mount with heavier solid axle. No sprocket size limits on Ms Peel rear going this route. Weighs about same as factory. MX bike race shops have more expensive kits in some what lighter mass. Sprocket side needed adaptor to mount sprocket closer to hub for chain alignment as Water Buffalo's were wider all over.

There were only like 3 yrs of spoke hubs with brake rotor mount til cast wheels became the cheaper heavier rage. No you could not afford me to make another one either.

I was hoping it would be an economical mod, not that the teeth on the rear wear out fast, but for convenience it would be nice to just change a sprocket.

If you stick with 530 chain plain or sealed rear teeth last a long time. Main advantage is ability to change ratio's and run Al sprocket to easy change them only as they will wear out much sooner on Norton torque. Wonder if new rear drums are being made or if we are using them all up. Of course there must be 10's of 1000's out there yet. I've ruined 4 of them myself in a decade, so more than my fair share - sorry.

About the only thing that could be done economically would be to find a worn out sprocket on a good drum and come up with a good sprocket of the right tooth count. I can take the sprocket and cut the center out and fit it on a machined drum and braze it in place. If you have access to the drum and sprocket then the machining and welding could make a good repair, but it wouldn't be a bolt up sprocket. It may be a better repair than a new sprocket. New ones are available but the replacements are not case hardened like the originals and don't last nearly as long. Jim

When I wore out 1st set of drum teeth i saw Norvil had 'replacement sprocket" so ordered it to find it must be for hill climbers but attempted to try it anyway. Had old teeth milled off to fit ID of sprocket then drilled around for allen bolts, half the thread in sprocket other half in drum. Worked but sprocket too big to fit on regular Cdo so just a dead end curiosity. Rusty drum photo is not worn out to me who uses them till old chain begins to slip on the nibbins, but does show thinned teeth starting to fan blade over to even break off. If chain can be lifted out of rear valleys its getting worn and amount of lift is where the load bares on teeth, as chain at speed is flung outward not pulled into valleys. Chain tension has no effect of this test. Hole in use are thin Al covered d/t THE Grit.