Brock's Performance Cracks 200 MPH on the ZX-14.

Because the new ones are so much better than the 10 year old one it's not worth it to keep them!



If you look at a bike like a EX500 that hasn't changed over the last 10 years you'll find more older ones. But all the real sport bikes are so much better than their 10 year old versions hardly anyone keeps them or wants them (hence they don't hold value well)



Where as HD's hardly change so the old ones are just about as good as the new ones and they're a lot more $$ than sport bikes so people tend to hold on to them much longer.



An EX500 is kinda similar - hardly any updates in 15+ years but it's a cheap bike ($5k new) compared to a HD but like HD they hold their value pretty well, better than the top of the line sport bikes.



If your buying a sport bike your buying it for it's performance, and in the last 20 years the hpr has almost doubled (in addition to all the other areas that have improved) so that's a BIG perfromance difference.



They're also very complicated so it can quickly become more worth while to buy a new one than do a rebuild on a 10 year old one.

As someone that races at WSIR track times definatly do not stay the same.



If you look at the lap records for various WSMC classes you'll notice -



the oldest WSMC class record is from 1996 for formula singles (which was probably made by a non-production bike)



~80% of the records were all made in the last couple years



Also note - the 500 GP record at that track is a 1.25 set by Eddie Lawson in 1991. The current 600 super stock record is a 1:21 ... and that's a 500 2-stroke GP race bike vs a stock 600 street bike.



So bikes have definatly gotten a lot faster around a track, half of it might just be better tires though, but a lot of it is the bikes too.