google jt sprockets youll find complete chain and sprocket sets,charts etc,dont let the numbers buzz your head,,race bikes will gear down or up for certain race tracks,,so more or less at the end of the longest straight is when top gear runs out,,sort of,,youll be happier with the standard gearing i think,dont get too ahead of what your building yet and go for performance only,youll want to enjoy the ride aswell,,a cheap late model could be bought for fanging around if you really wanted to,having said that ive always geared my dirt bikes right down as the riding we would do always encounted some really slow stuff and the two strokes i had like to be kept on the boil,,i didnt care for top speed as we rarely got flat out in top(castlemaine victoria)