Im in the process of building a borad bow from Hickory.  Ive finishe tillering and one limb is bending too much.  If I remove wood from the other limb the bow will lose all strength.  Is there a way to stiffen up a limb?  any help

You can add a backing if the back is reasonably flat and wide enough to glue.  The surface of each piece will need to be roughed so the glue will hold.
The you need to CAREFULLY rework the belly to even even tiller on each limb and hopefully overcome the hinge.

One of the Cardinal rules of bow building - you cannot put wood back!

Your best bet would be to even up the limbs first, then pike both equally to gain the weight back. Did you just remove too much too fast, or did you get a hinge? Pics and specs would help.

If one limb is bending too much then you aren't finished tillering.  Keep going until they are even.  Then you may be able to increase weight some but don't expect miracles.  

It is very common to miss weight on first bows.  Just keep trying.  It will get better.  Just keep at it.  We will help if you ask.

I've added belly slats to several bows and also put a thin patch in over a hinged area with success.  The hardest part of doing this is to get the belly flat and mate the slat to it very carefully.  I use a hacksaw blade to roughen both of the mating surfaces, then glue with smooth on epoxy.  I clamp sung, but don't starve the joint of glue.  When cured 24hrs, unclamp, clean up and re tiller.  All this being said, it is probably quicker and cheaper to just start over.

Thanks to all for the advise, I'll let you know how it goes

Wee all faced the problem of low poundage bows on first tries. It's part of the learning process and it you circumvent that process by adding wooden backings, etc you'll never learn how to bring in the weight. Finish tillering asJohn advised. Then start another. Take a look at my site. Jawge
http://georgeandjoni.home.comcast.net/~georgeandjoni/index.html

thanks  I took more off the other limb to even things out.  Did drop poundage.  I'll keep trying.