If I read you right, the above replies are helpful, but whay you really want to know is "why?" you aren't hitting those speeds, right?
Hard to answer w/o pics, but I agree, at 26" draw, you might be underworking a 66" bow. That's 30" of working limb on each side of a 6" handle, for rough figures. There is an old rule of thumb (and it is JUST a rule of thumb) that bow limb length should about equal draw length. Limbs will cost you cast if they are longer than needed, heavier than needed toward the tips, or if they bend in the wrong places.
Things that help cast..
Stiff tips (on most styles). Stiff tips several inches long are made skinner and thicker, saving a lot of weight, improving full draw string angle, and quelling some of the limb vuibration.
Toasted belly. Allows narrower overall limbs at the same draw weight, again, reducing physical weight of the limbs.
Low set. Set, esp excessive string follow robs you of good tension on the string at brace, which causes less stored energy (esp. early in the draw) and can add vibration at the tips.
Reflex, or recurves, add early draw weight. However if excessive the wood may not "take" the strain and increased set results through the working limb.
A strong lightweight string. A heavy, overbuilt string, esp. one like nylon that stretches with the shot kills cast.
There are a couple more, but if you want to look at your bow and see if you can "tweak" it for more speed go ahead.
On the other hand, you have two nice successful bows there. Kkeep em and improve on the next ones...