hi, iam doing a small project(rc plane) for which iam using an AVIONIC 380KV motor with 80Amp ESC(inbuilt UBEC) along with 6S Li-Po battery(22.2V 8000mah 25C).. But when i connect all these for testing..the motor is not working properly..its glitching or just vibrating. when we check for faults and we tested with a 4 cell 35C battery, it worked..i want to run it on 6S battery..Please do help me how to adjust it...Does adding a capacitor(25V) solves the problem. Please help me....

According to me, the motor would vibrate only when there is a lose connection/ short circuit between the motor and esc. But since you say that the motor works fine with the  4S, we can rule that possibility out.
There can be two problems according to me:
1) The 6S connector is faulty or There may be some place where the wires may be loose. Maybe inside the battery. Have you tested it elsewhere?
2) The specific ESC/Motor is not designed to take on a 6S. Are they both certified for 6S Operation?
Regards

Thanks for your concern, Ive got the motor from RCBAZAAR IN BANGLORE 
http://rcbazaar.com/product.aspx?productid=8315
It says tht we can use a 6cell battery

What about the ESC? Is it 6S compatible?
Have you used the 6S elsewhere? Can you confirm using a multimeter if the voltage is 22.2? Move the plug around while checking with a multi. If there is a loose joint somewhere, it may show up.

Do you have any other ESC or motor which supports 6S configuration so that you can conclude the reason for problem. What ESC are you using? Can you provide the specs and also you can try searching if someone else face the same problem with that particular ESC.

Dont forget to check you motor connection A-B-C wires... it is symptomatic of a loose connection. maybe a couple.