Can I paralleled a 36v 8ah battery with a 36v 14ah battery on my electric scooter?

I do agree with aspects of the other answers, but you must understand the difference between the different electrical values.

i.e. your battery voltage is 36V. So, your bike needs a 36V push of electricity to work. Anything less and it probably won't work and anything more could damage the motors and other things.

Golden rule --> always match the voltage.

The Ah rating is the amount of current the battery can deliver/hour

e.g. 14Ah --> 14 amps for 1 hour

or, 7 amps for 2 hours, e.t.c.

The higher the Ah value just means the battery will hold more charge for longer due to its greater capacity. The downside is that it will take longer to reach a full charge when charged up than one with a lower value.

Your bike is probably rated at a certain power (Watts). This power will draw a current for the value of 36V

So, if for example, your bike is 360 Watts then we have:

360 = 36 x I

i.e. current of 10 amps

Your original battery, rated at 8Ah will mean just short of an hour's riding. The new battery, rated at 14Ah will mean over an hour's ride. 

I wouldn't join any of them together, just get a 36V battery with the highest Ah rating.

Also, if connecting in parallel, you must have the same voltage. DO NOT connect in series by mistake as you will create 72V!! Bear in mind that even if two batteries have the same voltage and same Ah rating, their internal chemistry always means there will be a slight (but important) difference in their actual values.

A long answer, but thought it was worth the detail.

:)>

Technically you can. Parallel only requires the same voltage.

it will work until the 8ah battery runs out of charge.at that point it will damage the battery (as it will overdraw it) 8ah is the capacity and 36v is the voltage.it is better to use the same capacity, as it will prevent damage in the lower capacity batteries. Not sure where "spacemissing" got his info but he is really wrong. 

All batteries should be of the same BRAND, 

the same exact Catalog Number, 

and the same CAPACITY.