There must surely be some way.....but the original is, in my experience pretty well made and with regular chain lubing and changing the chain out when it gets plain too stretched and starts to "pop" on the teeth, will surely make it that you don't have to just replace the thing so often.
I know the Japs sell new chains and sprockets together as a set as a standard practice...but that wouldn't be really necessary if the sprocket was well made in the first place, and you do your maintainance like a good little "DoBe"...
Mine is still the original. I change the chain out every couple years at the most, keep the chain well adjusted and really well lubed and the sprocket has lasted a "bit" now and still no noticable wear. 125 thousand or so....miles.
Not like that piece of junk sprocket they sell for the Suzuki my son tears up the countryside with...that needs replacement twice a year....
When I was a kid my Dad had an ES2, which I think was the same hub and rear wheel as a MKI Commando. His rear sprocket was toast, so he turned off the teeth, turned the center out of another sprocket and welded it into the drum.
I'm wondering about doing the same thing, except using a drilled flange to accept a modern sprocket, similar to the one on my Hinckley Daytona. It's a big ring.
Aside from finding a suitable modern substitute, my main concern is the necessary gain in size to make this work. My bike is geared too low already, and the only way I can think to compensate for it would be a bigger engine sprocket.
The gurus will most likely correct me....but I think the front sprockets go up to 24 teeth...I know the size up front will be limited by the lube splatter guard on the back of the inner primary case...but that might be able to be removed. Seems your idea could be done...just not sure why you would want to if you can get a good used rear drum...but...you must know...and I quess that's what matters....changing the size of sprocket in back though, will change what you need for a chain guard, maybe get the chain near the center stand...etc..etc. Might be a headache, and not much improvement.
I learned this one from Rob Tululie -- go to your local breakers and get a rear hub from a mid-70's drum-braked Kawasaki KZ650. Mine is laced into an 18 inch rim, though 19 would likely also work. You'll probably have to make some spacers and figure out how to route the brake cable to the other side (my commando is right-hand shift). Gives you an okay rear brake and pretty easy to change gearing.
I found out through personal experience that the casting to which the brake steady mounts will fracture if you high-side at Gingerman. Since I have the broken one on the shelf, the part number on the brake shoe is ASK1037SR2FF. Not sure if that for the shoe or the entire hub, but thought it might be helpful.
Hi Captain, Yes, the drum has been modified ( I paid someone to do it)
It has a steel ring welded to the outsideod the drum. This is drilled and tapped to take the bolts that hold the sprocket on. Due to the extra diameter of the sprocket, the smallest rear sprocket is a 47 tooth.
Since standard gearing is 21/42 ( 2:1) I can fit a 24/48 to give the same final drive ratio. Obviously a 24/47 is one tooth higher geared than standard.
I'm not sure what the maximum sized gearbox sprocket is.