Fork bottoms - chainging 20mm > 26mm. Can it be done?

I have a 650 Berg with the smaller 20mm front axle.

I was wondering if it is possible to change the fork bottoms from the 20mm axle to the bottoms found on Berg with a 26mm axle?

What are they held on by???? and can a fairly experienced mechanic (no problems with breaking Berg engines into litte bits & putting them back together) do it, or is worthwhile spending £100+ for a suspension guru to do it.

Any help would be great before going doing something I may regret!

Cheers

Rosco

Okay, I shall explain the situation further, I warn you that it may get confusing;

I have an 02 650 Berg, that I do supermoto with, that breaks down on me every other day. The last time was the last straw. On it's way is an 04 KTM 450sx. The 450 comes with supermoto converted forks. My Berg currently has race converted forks also. My pal has an 05 KTM 525 with standard suspension.

I would like to keep my forks that I have on my Berg, as they are suited to me. My pal would like to buy the race forks off the KTM 450. I would get some money plus his standard forks in exchange. I would like to change over the fork bottoms (from the Bergs forks to the 450's forks and vice versa) so as I can keep using the 450's existing wheels etc. The reason for this hassle is so I can sell my Berg as a standard rolling chassis and keep the KTM standard sized front axle.

I know the rear bottom shock mountings differs between the two bike also but this looks easy to change over. I don't know how the forks bottoms are held on, whether by friction (push fit), bolted from the inside or the outside.

Whew. I think that's me!

Ta