I have a P-51 with a Saito 100 in it. It has mechanical retracts in it and on occasion I have to go inverted to get them to go up. I was wondering if the battery I am using has enough amperage or if the servo may be just weak. The battery is a 6v 1600 Mah. Is that a strong enough battery for mechanical retracts? I have put a 2300 Mah 4.8V in it and there is very little difference if any the 4.8 may work a little better but still slow when coming up.

I don't know about the servo and the battery.

This is just an idea:
Could you engineer a spring mechanism that work with the servo in the up movement and against the servo in the down movement?
That would liberate the servo from lifting the whole weight of the gear.

The battery is big enough. What retract servo are you using? I use the JR791 on my mechanicals. You may also need to readjust the linkage to make sure the travel is locking the gear.
Edwin

I remember having problems where the UP was a push action, and the rods I was using were too light, and flexing.

Les

Do your retracts have any fore/aft slack in them?

On my P-47 they do & retract fine on the ground but with air blowing against them in forward flight they foul the rear of the wheel wells stopping them from retracting fully.

I just adjusted them so with them pushed back they no longer foul the wheel wells. - John.