[DarkCRF]

On my girlfriend CRF150F 2011 I gonna change the front suspension with a CR85R 2005 little wheel forks. I know the bike is really heavier so I can't rely on the different spring rate calculator website.

What spring do you recommend for my girlfriend

Novice, trail riding (smooth track soon)
Weight 120 lbs without gears

[dsrpilot]

There are some folks that specialize in this conversion. You may want to check out the site to see if any of their products will help in your conversion.

They can also help you ascertain the proper spring rate based on the information you provided.

Here are two of those companies:
http://www.regerengineering.com/

http://www.xr100.com/crf150.htm#CRF 150 SUSPENSION

Ken may have some solutions here at CRFs Only as well...