I have noticed how high my engine revs when traveling at 40mph (5500rpm) and want to know if there's any way I can lower the revs, as I do lots of miles it must be hard on the engine.

Pulleys and belt are in good order and the clutch setting is standard, weights are 1 gram heavier doctor pulley's

[2015 Z Force 800 53/Trail EPS]

B1 is as low as you can go with the secondary unless you find a lighter spring. The only other thing you can do is increase the Primary weight. You are already one gram over the stock which is 25 grams so you must be at 26 grams. You can go more but know it will cost you low end...a lot.. 5500 isn't that bad. If you watch I'll almost bet it only gains another 600 or less to make 50.

ok thank you

It is operating as it is designed, if you are worried you are revving higher than it is supposed to.  Small engine low horsepower output needs the RPM to move the machine along with a CVT clutch set up. If it makes you feel any better my jet ski revs about 7k at 40mph =)