Safe to power 2 hacked knex motors with a 9v battery?

hello all, newbie @ electronics, , c language (i have experience in other languages).

i have question powering knex motor in http://www.instructables.com/id/arduino-robot-for-lowest-cost/step2/hack-the-knex-motor-drive/ tutorial. normally, motor takes 2 aa batteries (3v) power it. wondering if motor safe power 9v battery. powered short period of time battery, , spinning fast, overheat consistant use? planning on using l293d power it, if cannot handle 9v, still work if sent smaller pwm pulse rate enable this:

code: [select]

#define speed_pin 11
//will send 1/3 voltage and/or amperage won't overheat if problem?
analogwrite(speed_pin, 255/3)

the motor not have information on besides company name "s. m. c. motor". did bit of searching, not find specs motor im using.

and if nobody knows, how long should run on 9v sure doesn't overheat?

quote

normally, motor takes 2 aa batteries (3v) power it. wondering if motor safe power 9v battery.

so think? result?

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