With motorcycles being such an expensive hobby, riders look to the used market to find killer deals on parts. Because they can be pretty heavy on one’s wallet, forks and shocks are high on the used parts lists. But just because you get a great deal on a used set of forks or shock doesn’t always mean you’re getting a better price then buying new.
First and foremost is fitment. Many times the same shock will fit a large number of different bikes, so make sure the shock being sold is the right one for your bike! Clearance and stroke length are key. On Ohlins shock’s its easy, just ask for the shock model. It will be 2 letters followed by 4 numbers and is usually located on the head of the shock. Examples are KA3450 or HO1450 (the first 3 numbers are the model, and the last number is the revision number). All other aftermarket shocks you just have to go by the word of the seller.
Next would be condition of the shock. How often was it refreshed? How dirty is it? Condition of the shaft? The concerns here are to give you clues on the condition of the shock internally. If a rider has the shock refreshed on a consistent basis chances are the internals will be in pretty good shape. Otherwise plan on changing seals, all the O-rings, and piston bands. Also when dirt gets into crevices and sits, it will start to pit the metals requiring parts to be replaced. The shaft of the shock must also be inspected to make sure there aren’t any deep scratches which would also require replacement.
The last part is the spring. “Sprung for a XXX lb rider” is not a acceptable description of a spring rate. The only acceptable description of a spring is it’s rate, either in kg, lbs or nm; do not accept anything less. And most of the time the rate of the spring or part number will be stamped on the spring itself. The part number will allow you to find out what the rate is.
When looking for a used shock these are key points to consider to keep the cost down. If additional parts are needed to get the shock set up properly, one might be better off just buying a new one. And do yourself a favor and get the shock refreshed and inspected before you put your new bling on the bike. Hopefully this helps you to make the right decisions to get the best bang for your buck.