[mrlmd1]

From another thread on here, just in case you haven't been following the action, from another bike source confirming what I had said----echos my comment, my opinion--------

HELMETS

* Used helmets are worthless. Regardless of whether it fits you or not, do not count the price of a used helmet as part of the value of the bike. The owner may want to sell the helmet, either because it matches the bike or because (s)he is quitting motorcycling, but since you'll be throwing the helmet out (or, at absolute worst, keeping it as a pillion helmet), don't count its value towards the sale price of the bike.
* Used helmets are worthless because you cannot tell if they are damaged or not, and in many cases you don't know when they were made. (Snell-certified helmets should have a date-of-manufacture stamp -- look for one. It might be under the padded lining.) Even if they look good, used helmets might well be junk. Motorcycle helmets work by allowing a layer of expanded polystyrene (EPS) to crush, absorbing much of the force of an impact. Unless the hard outer shell is damaged, you cannot tell if the EPS inside is compressed or not. And even then, sometimes you can't -- covering damage with stickers is just as common with helmets as it is with plastic fairings.
* Furthermore, EPS becomes more brittle as it ages, and old/brittle EPS has only a small fraction of the original impact absorption abilities. And since you may not know when the helmet was made (who cares when the previous owner bought the thing), you don't know how "fresh" the EPS is. The EPS layer in helmets is also highly vulnerable to ultraviolet and chemical damage -- if, for example, the helmet's owner was in the habit of resting the helmet on the bike's gas tank, gas vapors from the fill cap have attacked and compromised the EPS lining. Or if the helmet was left out in the sun a lot, it could also be damaged from the ultraviolet component of sunlight. Arai (a leading helmet manufacturer) cites acidic sweat as a leading cause of premature EPS degradation. The EPS can also be compressed if the helmet is habitually rested on pointy objects like mirror-stalks or handlebars. The bottom line is, despite what the owner says, you do not know what condition the EPS liner is in, and the EPS liner is the vast majority of the helmet's crash protection.
* It's not worth the risk. Yes, in some cases, you can send the helmet back to the manufacturer to have it X-rayed. But that will only tell you if the EPS liner has been compressed, not if it has been chemically damaged. Since you'll never know for sure, buy yourself a good quality new helmet from a good quality manufacturer, and stay away from used helmets.
* And if you're still thinking of using a used helmet, realize that helmet fit is one of the most important criteria in selecting a helmet, and it's highly unlikely that a used helmet will fit you as well as one you get from a shop, where you actually get to try different sizes and brands. (Shapes vary subtly by manufacturer; some manufacturers' helmets will fit you better than others.) And if that isn't enough, helmets tend to break in as the padded liner conforms to the unique shape of the wearer's head. You have a different-shaped head than the seller. Get your head its very own new helmet.