Jackpot when you are looking for bike parts is when you see New Old Stock (NOS) parts.
These are the kind of things that have been sitting around in a workshop or garage, but never been fitted. Any decent bike enthusiast is likely to have a few such things ! They can be anything from items bought but never fitted, to semi-consumables like gaskets and oil seals that were bought to be ready for when they would be needed in a hurry.
Things to look for when buying NOS parts, or parts claimed as NOS;
1. Do they have the original part label ? It's not the end of the world if they don't, but a label showing it's an "offical" part not only identifies that it's made by the manufacturer rather than a pattern part, it also gives a part number which you can use to check it's the right bit for your bike.
2. Is it in original packaging, ideally still factory-sealed ? Many parts will have been taken out of their packaging to be checked, and then put back in. But if the packaging is still factory sealed (Honda, for example, often heat-seal theirs, whereas Kawasaki staple or vacuum seal them) then you are much more likely to get a part that hasn't deteriorated with time. Don't worry if the packaging is grubby and oil stained - it's the condition of the part inside that counts !
3. Is the seller clear in their description (and photo) that if the packaging has been opened, the part really IS new and never been fitted ? It's not unknown for more unscrupulous sellers to pur a used part in a pattern bag and try to pass it off as new.....
4. Does the seller give the part number in their listing, and do they say exactly which models the part fits ? With the parts I sell, I always give the part number, and do a considerable amount of work to list all the models I can find which it fits, as well as (where possible) the sub-models and years. It's amazing how often a part is recycled, often on a scale of decades, to be reused by the manufacturer on wildly different models. Honda are the masters of this, and Kawasaki when it comes to front braking systems ! Equally, you have to be careful that two models just a year apart haven't had a part updated with something completely different.
5. Do your research on prices. I've seen parts for particularly cherished models go on ebay for FAR more than you could get them for from a decent dealer. Of course, often you'll be able to find that rare part at a real knockdown price, especially if the seller is just trying to clear some garage space !
Hopefully this information is helpful to you. I've both bought and sold parts on ebay over a number of years, and made my fair share of mistakes ! One day, I'll get my old Z650 back to immaculate condition, honest !
When I find time, I'll write another guide, this time covering part numbers, what those strange numbers all mean, and a few tips on how to use the information to find that elusive part on ebay....
In the meantime, I usually have a few NOS parts listed on ebay, or in my shop;