My kawasai zr 7, 2001 revs too high in top gear, chain sprockets are, 16, 39 is this standard?

Inside the tank...plugged into the fuel tap

The chain is doing the chewing, not the sprocket. Chances are a spacer behind the sprocket is missing or an oversize chain has been mounted on the bike. Please rate my answer.

apart from the obvious check air filter is clean spark plug is good and your pilot jet in carb is all clear form dirt or gummed fuel my next step would be put a tooth or two bigger rear sprocket on it to lower the gear ratio this will give more torque low speed maybe whilst you looking at the sprocket just check that some has not change the front to smaller sprocket it being few years old some one may have set to get more top end speed and sacrificed all the low end??

you can change the sprockets.If you go to a 16 tooth front sprocket. two teeth on a front sprocket is like droping 4 teeth on the rear. You could drop 2 teeth on the rear sprocket but a 43 tooth is probably harder to find. the usual choices for front are 14,15,16 tooth.
For the rear they are 44,45,46 tooth

The way to remeber gearing changes is on REAR sprocket is smaller=faster and larger=slower top end.
the FRONT is OPPOSITE to the rear smaller=slower and bigger=faster.
You may have to lengthen or shorten the chain depending whjch way you go.

I am assuming when you say changing from high gear to low gear you are talking about changing the chain drive gears if so yes it can be difficult because the rear wheel must be removed and also the front sprocket must be held stationary in order to unscrew the hold down nut, this is usually the hardest part of the job but not impossible. Don't forget that most people that change the sprockets to increase off the line torque usually change the sprocket in sets unless you want to shorten or lengthen the chain, sometimes this si neccessary other times the chain slack adjustment range will allow you to get away with not needing to lengthen the chain, this only applies to people who decide not to chain the sprockets as a set.

u don't want to much play in it cause if it is to loose it will wear out the sprockets very fast but it will do the same thing if the chain is to tight it will wear out and stretch the chain out.

think usaualy the bolt goes allthe way through

Check your chain and sprockets, sometimes the chain wears the sprocket out, "curving" the teeth so it hooks the chain. You probably have the ticking in lower gears as well, but it only hooks the chain at speed - and in 6th the engine revs are lower, the engine is quieter, so you hear the chain easier.

lowering and rideabilty will effect and costly

solution
can wear platform boots to give you extra footing needed

for neu when hot sounds if clutch needs a little more adjustment to dis-engage

no you **** going bigger in the back is more accel, smaller is more top end. a 48-46 would put you somewhere between 80-100 mph depending on the engine but result is **** low end. If your kx is 6 spd you would benefit from going up a tooth or 2 for lowend because it has topend already.