Can anyone who has built this plane help me with balancing. I have the radio installed and the engine temporarily installed at the end of the engine mount and I still can't get it to balance. It's tail heavy. I don't want to add any additional weight to the nose. I have an OS .70 Surpass 4-stroke in it at this time. I'm trying to balance it at the main wing spar. Any suggestions?

Thanks,
Jim