I still have the Kawasaki KT250A that I bought new in September 1975 (my first bike), so thats 35 years.
I also still have;
My 1978 Husqvarna 390 AMX, 32 years. (its in bits in boxes)
2 x 1974 Cossack K650 Dneipr's, bought from a pastoral property in 1978. 32 years.
My 1979 (Model 199A) Bultaco 350 Sherpa that I was given by my parents for my 21st birthday, 30 years. (again in bits in boxes).
A 1978 Yamaha SR500, bought 2nd hand in 1980, 30 years.
A early 70's SL125 Honda, bought from a pastoral property in 1982. 28 years.
A 1962 Honda C72 Dream (250cc) bought from the original owner in 1983. 27 years
A 1964 Honda C102 Super Cub (50cc) I swaped a BSA Banten for in 1983. 27 years
A 1949 Matchless G80 (500cc) Built from parts in 1983. 27 years
There are a few others in the collection that I have had for over 20 years, but I think you get the picture that I rarely get rid of any bikes. Hopefully, in the new year I will start a rebuild/restoration of a DT100A, that will be built up from the remains of my two elder (twin) brothers' DT100A's which they bought new in 1974, (and we eventually trashed in the early 80's) and the remains of another which I found on the local tip a few month ago.
CJ