Problem?
 

Managed to get the first ride out today since the rather cheap service :o..

Bike feels really tight and the new gearing has made a superb difference.

I did notice that she back fired a couple of times when I was approaching round abouts. It only did it a couple of times, is this something I should get checked out, or is it ok to leave it.

I know that my bike is running rich, I guess due to the cans, but why didnt it happen before the service?

Lloydy

a back fire is usually indicative of a weak mixture.
Fitting open cans would also lean the mixture off to.

If the bike was set up with a CO meter during the service, then they could have set it to factory specs, which is about 1.5% CO or less I think. I seem to get best results, especially with cans fitted with it set at around 4%.
If the throttle sensor was reset, that could have an effect to.
Worth mentioning the backfire to them and have them recheck or adjust the mixture for you.