I ordered lighter rollers have always ran three. i had a 50cc chinese scoot than ran three rollers over 4500 mkn with no probs other than when i took them out they had flat spots lol
in my experience....
on some scoots it increases take off but limits top end
on others it doesnt affect anything for som reason
on others it increases top speed but rpms rev higher
on some it increases take off without affecting rpm's that much but also not limiting top end, which is wierd but i still cant figure it out.
i do know that when you run 3 rollers at a time, when replacing them use the other slots instead of the ones you just used so mark the three slots you take the ones out of or mark the slots you need to use while the others are in. this keeps any possible wear pretty even but ater that many miles the onyl signs of wear were on the rollers themslves with the flat spots, the sliders were fine.