I've been looking to do the camshaft mod on the SF but the more I look at it the more it doesn't make sense. The way it's explained is you're going to move it at tooth and a half bringing from 110 degrees to a hundred degree but in reality you're just repositioning the camshaft gears and not moving the camshaft themselves so how is that going to change the timing of your cam duration maybe I'm misunderstanding what is being done..
has anybody ever done this with positive results does it actually work.

 

You you need to carefully read the whole operation, visualizing what is going on. The cams are moved by switching the bolt holes (a 2-1/2 tooth change) moving the cams past the desired point, then the cam/gear assembly is moved back two teeth, resulting in the desired 10 degree offset making for the timing change. Cams definitely moved, timing changed. Marcelino explains it in detail in the sticky post in the KLX250 sub-forum and there are probably at least a few dozen riders here who have done it, myself included. I have also seen a similar cam timing change on a Honda Nighthawk S, but with slotted cam sprockets. Both were working toward the same timing goal, which gave better mid-range power.

Here is Marcelino's article quote:
"Well the solution is at follows :
For intake we give it 2 and a half teeth more advance by puting the screws in the position that corresponds to exhaust and then we retard the camshaft 2 teeth in the chain . The difference , as far as the cam is concerned , is a 1/2 tooth ( 10-something degrees )
For the exhaust cam it´s the same , but in the opposite direction : we retard the cam by puting the screws in the intake position and then we put the sprocket 2 teeth more advanced in the chain . This cam will de 1/2 teeth retarded ( 10.5 degrees ) ."