Floyd,

Is it a Graupner motor?  Most Speed 400's were either 4.8v, 6.0v, or 7.2. The higher the voltage, the lower the Kv.  I used the 6v on 7 NiCad cells in my Speed 400 racers a few years back.  The 6V motor on a 2S lipoly would be a lot of fun in a 1/2A stunt or combat ship.  Just beware they run at a whopping 50-60% efficiency. 

The reason fo everyone using brushless right now is they are just as inexpensive anymore.  Plus they don't where out if you don't go beyond their capabilities.  Speed 400's are throw away motors. Once the brushess are gone, it's over.

Archie Adamisin
Muncie, Indiana

Use an Emax 2805-2800Kv on 2S 1250's and a 6 x 4 APC prop.  It will be lighter and more powerful than both other options.  The motor is $5 and available on from Hobby City.  A 15 amp turnigy controller and a Will Hublin simple timer and you are set to go ECL. 

Archie Adamisin
Muncie, Indiana

Lester,

It depends on prop.  If you want to stay with the 1/2A 6" prop rule, use the 2840 Kv.  I have 6 of these motors and they rock.  The 1600 Kv would swing up to a 9 x 6 on 2S, or 7 x 5 on 3S.  Note, there are also some tower pro motor/prop/esc combos that work nicely.  They have a 2408-21T which is 1700Kv that comes with prop 9 x 4.7 and controller for $14.  I use these for RC foamy combat models.  They are simple bell motors/CD rom motors, but I have hundreds of flights on several and they run great. 

Controllers, I would use the Turnigy plush 15 amp with Turnigy programming card.  I have also used the Tower pro 18 & 25 amp controllers with no issues.  They are cheaper yet.

Archie Adamisin
Muncie, Indiana