I have a 2002 Vstar 1100 custom. If I go to a single backbone with a 2" stretch and add 2" to the down tubes. Will a 2" fork extension bring the rake back to factory rake.

I'm not sure...... but you can use this calculator to figure it all out.

RB Racing Professional Rake and Trail Calculator (rbracing-rsr.com)

i would be very weary of the screw in fork extensions. i had a one break on my 1100 at speed. i found that getting longer fork tubes was more expensive but safer.

The answer is no. Rake is the angle of the neck. If your wheel assembly is stock and you set the neck angle to factory setting your rake and trail will be stock. This is up 4 out 6  

That is about the look I was going for. So if I go out 2-3 then add 2" the the forks I can just make the "up" whatever it comes out to. As long as I keep the rake around 35 I should be ok. Right?

I think the stock rake is 34* , 1 degree one way or the other for road bikes doesn’t effect it much. Keep your ride height (static) level, set the neck and angle, measure the fork length. You might look for Franks forks for new tubes. Only going up 2” is a waste, for the amount of work you’ll be going through, my opinion. 
Is this a romantic thought or are you serious about proceeding? If you’re planning on doing it yourself are you a capable welder? There are many things that have to be thought through. 
 

This is gonna happen. Welding will be no problem.  I have a vstar 1300 frame with the single backbone that I will be putting in. Not really stuck on the 2" longer tunes. Just a thought.  Gonna see what it looks like after the single backbone.

Yo Dennis!

Yo Dennis! Great to see you! hope you;re well!

Hi Mick!

I’ve been doing well, thank you. I’ve got the hot rod in the shop slowly going through it end to end. Just need some new shoes for it and I’ll be done. (I hope) I’m glad I have the Street Glide to ride in the mean time.