new Li-on or lipo instead of old NiCd

Hi
I recently found a Kyosho HyperFly Helicopter in my garage its an old RC helicopter (it's about 13 years old)
I would like to try and fly it .since the old battery(7.2v 1100mAh made of six NiCd cells) is dead need a new battery.
I was thinking of maybe using two dx 18650 2400mah Li-on
(because i already own the batteries and charger )
is it possible or would the over heat ? would it give improved fly time
if not how do choose a Li-Po that would work? what discharge level is good enough ?

thanks
issarh

P.S. this is alink to it's instructions http://www.google.com/url?sa=U&start=3&q=http://www2.busybeemfk.se/phpgraphy/index.php%3Fdisplaypic%3DRitningar%252FKyosho%252FHyperfly%252Fkyoe0225-manual.pdf%26mode%3Dsaveas&ei=pxD-SejaBNDOjAfWsJCdAw&usg=AFQjCNEAzpVLSsG3n9dVuf6L5NMrM6Ejag

I am looking for a hyperfly, If you get bored with it I would like to purchase it. name your price and we can make a deal.

adam

You would want to go with Lipos. Usually, Li-ons have a max discharge rate too low to run a RC type motor.

Lipos usually have a max discharge of 10 times capacity or more. Li-ons usually have a much lower rate.

Lipos are fairly cheap and low weight. I would go with two in series to get your 7.4 volts and at least the capacity of the old NiCds. They are so light though, why not go twice the capacity or more and increase your flying time.

Also, speaking from experience, I tried to run a RC helicopter that used 7.2v NiCds of around 800ma on two Li-on 17500s. The motor wouldn't spin fast enough to get off the ground and the plastic casing wrap on the batteries melted!