I just finshed building the Great Planes Ultimate 40. I have mounted the battery pack on top of the fuel tank and I still have to put more than 7oz of weight on the engine mount to get it slightly nose heavy. What I would like to know is how much is to much weight.

There is no magic number. Most planes will fly heavyer than recomended. the drawback is
it effects the way it flys. More so at lower speeds like on landing. Small bipes are worse than most.
The nose just isn't far enough in front of the CG. If there is any radio gear you can move forward do it.
The battery on the tank is a good idea. Sometimes the throtle servo can be put right behind the tank also.
If this is your first bipe you have a learning curve on landing anyway. remember to keep a little power on
and don't just cut the power and glide in. Most Ultimates stall straight ahead and not left or right. If your engine
is broke in good do a couple of stalls at 200ft. When it does stall it might just come down nose level at a 45 degree angle. A trainer will just nose over at stall. An ULT might not. Horsepower is your friend so don't be afraid to pour the coals
to it if it starts to fall out. Good luck, later daveo