The extensions i have are hollow because the spring is preloaded from the top {lots of adjustment}, i also had the spring preload rod extended so they still function like stock, do some measuring, you may not feel the need to have extensions, i want them so i have room to fine tune ride height and suspension settings, i'm a bit anal retentive when it comes to suspension, i like to get it perfect and i have a friend that is a suspension guru. My forks are the 43mm 1989 GSXR forks, the earlier models are 41mm i think and have an anti dive set up on the lower fork legs. Look at Suzuki Bandit fork legs, they also have a better offset on the triple clamps. I am having custom triple clamps made up, the rearon being, the K model Honda have a 60mm offset, the GSXR clamps i have are 35mm offset, that increases trail and slows down the steering requiring a bit more effort to turn in when cornering, i am having clamps with 50mm offset made up so i am close to stock dimensions with a little more stability, i am using an 18 inch front wheel. The rear swingarm is a bit more involved, i had the monoshock section removed altogether, the arm was shortened at the rear, it is now around 40mm {around an inch and a half} longer than stock, it is a direct bolt in as it is the same width as the Honda arm. Here's a pic of the swingarm, it is from a 1988 GSXR1100J.
That picture is actually in a F1 750/4 frame...
