Looking into changing rake to + 3 deg and extending front forks 4" on my XLC, any reasons not to do it?

4" would be to long for starters

Thanks walka. Trying for 35deg total rake and 5.7in trail. Going with cups for the rake so that will use up a bit of the +4" tubes and should leave me with enough to play with to get the trail and total rake where I would like it.

no reason at all mate, do it right and have fun.

Not going to work, Sportster Frames are 30 Deg, Raked Cups come in 3, so your only at 33 Deg, For every 3 Deg of Rake you only add 1" of length to the Tube to keep the bike at the level ride hight, If you can find 4" over Tubes it is going to lift the front of the bike way to high

Thanks for the formula "walka". The bike sits low at the back so that should add a bit of rake to the stock rake plus I will be using cups which will use up some of the 4" above the neck.
Hopefully adding the extra length and the 3deg cups will raise the front enough to give me the extra 1.5deg to get to the 35deg I am after and the extra inch in trail. I guess +3" tubes would be better but the 39mm +4 were the shortest ones I have found. Plenty of 41mm but the 39mm seem hard to come by.

Easyriders in Japan do these 150mm extension tubes.. Ive seen the bike in the flesh, it sits so high at the front, must be fun to ride!!
http://www.easyriders.jp/webstore/details_hd.php?syohin_code=H3272

 

6" slugs, no thanks, they caused a lot of greef in the 70's