I just built a four star 40. when I checked the CG at the main wing spar the nose was really heavy. On my last plane (kadet LT 40) the tail was heavy and I just added weight to the nose. Befoe I add weight to the tail on my four star how balanced does it need to be?

It should be within 25% and 33% of the wing chord back from the leading edge. The farther back the CG is, the more aerobatic it will be, up to uncontrolability.

Remember, nose heavy planes may fly poorly. Tail heavy planes may fly once.

Dr.1

Lift it where the manual suggests, it should sit level, or very slightly nose DOWN (With the tank empty)

You are balancing upside down, right?
Just making sure.

In answer to our question: IT needs to be balanced !!!! Now before you add any thing to the tail, make sure you have everything as far forward as you can. DO NOT add weight if you don't have to and if you have to, try to add weight that is usefull.
ENJOY !!! RED

The plane needs to be fairly close to allow it to fly and give you decent performance. If the plane is too nose heavy it will be sluggish and not very responsive. If it is tail heavy, it will range from VERY sensitive and aerobatic to uncontrolable.

For maiden flights flights AND until you get used to the plane you want a SLIGHTLY nose heavy configuration. Balance the plane upside down with an empty fuel tank. What you are looking for for a slightly nose heavy balance is for the spinner/engine crankshaft to be ABOUT 3/4" - 1" below level.

Since you are nose heavy now I sugest the following BEFORE adding any weight.

1. Move your battery as far back as you can. If need be, use a HEAVY DUTY 6" extension to allow you to move it further back.

2. You can easily secure the battery inplace by CA a piece of velcro to the fuselage floor and wrap the foam insulation around the battery with masking tape, then adhere the other part to the masking tape. This will provide a very secure mounting that will allow you to remove the battery if needed, yet still keep the battery in place in all but the hardest of crashes.

3. If the plane is still nose heavy, seriously consider getting a larger capacity battery. Perhaps an 1800 mah or 2100 mah battery.

4. Use lightweight (foam ) wheels instead of the regular wheels.

The above tricks should balance the plane (or come very close ) without adding any weight. If you have to add weight, add it as far back as possible.

Well, I came home from work and tried balancing my plane upside down. It is still nose heavy but I am going to try and rearange my battery and receiver set up and try and shift some weight. That's is a great idea. I was worried I was going to have to stick lead to the outside of my fuse tail. Anyway, thanks for the help everybody.
The Four Star 40 directions are pretty iffy on the CG balance instructions. I will let you guys know how the first flight goes. I'm running a "heavy" supertiger 40 and using a Futaba skysport 6 radio. My other plane (kadet LT 40) is getting floats and a new engine. It has a 15 year old O.S. Max 40 on it that is literally falling apart at the crank case. That thing has been on like 8 planes throughout its life. Good ol' engine.

thanks again!