Lighter weights = Better acceleration, Heavier weights = Better top end.
This can be a bit misguiding as people will tend to assume that heavier weights
will give the bike better acceleration near the top speed OR a higher top speed.
The first won't happen, and the second will happen only very rarely.
I have 16g sliders in my Yager and I just ordered a set of 19g sliders. I do a lot of riding at 60 - 65 MPH. I'm hoping the RPM's will be lower at top speed.
What's the stock size of the weights?
If it's anywhere near 16g, you probably overdone it with 19g.
Because of the way sliders work, even going 10% less then stock rollers can drop your
top speed, because it won't let the bike rev out high enough. That's what happened
to me when I went from 15.5g stock round ones to the 14g sliders on DT300.
It's probably even more pronounced with smaller engined scoots.
I'd move 0.5g or 1g at a time.