i am new to lipo batteries
can someone tell me why my great plane flat out runs on a 11.1 v lipo with no problem
but if i use the same battery on a electric fly 370 motor on my lil poke it burns up the motor
the part number for the replacement motor for a flat out is the same motor i use on the little poke and it burns up
should i switch to a 7v volt lipo for the lil poke(will it be enough power?)

The battery voltage is generally too high for a 370 motor, you need to use a 2 cell lipo (7.4v)
The actual voltage of a 2 cell lipo starts off at 8.4v and drops slowly to 6v as you use it up, so one of these will be fine.
I use a 2 cell lipo in my 380 powered piper cub, & flies great on it.

The motor in your flat out plane that you say is fine on the 3 cell 11.1v lipo, will be because the current draw will be much lower, by being driven through the 5:1 ratio gearbox to reduce the load, so this is why you can get away with it on that one.

thanks for the advise
im starting to understand more about the amps being drawn,gear drives and prop sizes

No problem,
theres an awful lot to learn about electric rc gear, and (I probably don't know half of it) theres so many variables to consider and choose from.
On one hand with so much choice it gives you the freedom of limitless opportunities, but on the other, with so much to take into account, it can be the biggest burden to try and work out what you need to achieve what you want.