I found a nice orange 40 tooth aluminium rear sprocket that would fit my 1290 at my dealer.
My question is are aluminium rear sprockets streetable or are they mainly for track use?
Thanks >>>> Mike

An aluminium sprocket won't last like a steel one will, but if the chain is kept well-adjusted and lubed then it shouldn't be too bad. I used them on a ZX-10R track bike for years and never had an issue.
Obviously that's just an opinion and no liability can be conferred in the event that it's wrong!

Edit: Congratulations on using the correct spelling of Aluminium! Good lad

I think that I will give it a whirl.
I assume that the stock setup can handle an additional 2 teeth without having to break the chain?

I installed the 40t aluminium on the rear of my 2015 SDR for 2000 miles and it looks fine.
I lubed it every 500 miles that I kept track of on my Trip2 mile-o-meter.
I am selling my 2015 soon so I will try it out again on my new 2018 SDR.
In dry weather how long should I go before lubing a steel sprocket?
Thanks >>>> Mike