The reason for short life of the chain and sprockets is usually caused lack of lubrication and quicker wear on the front sprocket.
Change the front sprocket regularily and use plenty of librication. Since you have a scottoiler that would rule out the lubrication issue
I get 40000 miles out of my rear sprocket and chain, but I replace the front sprocket every 10000miles.
The front sprocket wears about 3 times faster than the rear as it is about 1/3rd the size of the rear. It only about cost about £7 for a front sprocket and will not be to badly worn after 10000miles.
This is the place for the bearings you require and are excellent to deal with http://www.marksman-ind.com/
Change the front sprocket regularily and use plenty of librication. Since you have a scottoiler that would rule out the lubrication issue
I get 40000 miles out of my rear sprocket and chain, but I replace the front sprocket every 10000miles.
The front sprocket wears about 3 times faster than the rear as it is about 1/3rd the size of the rear. It only about cost about £7 for a front sprocket and will not be to badly worn after 10000miles.
This is the place for the bearings you require and are excellent to deal with http://www.marksman-ind.com/