which model had decompressor

i have been offered a husky not sure of year or model didnt take engine number but the owner thought it was a 125 but the engine seems a lot larger than my 390 and its fitted with a decompressor valve in the head any one have idea without going back and investigating more ? definatly not 125 poss 400 ?

My 73 WR250 had one, but I don't know if it came with it stock. But can't imagine why someone would ad it on later.

thanks

intresting ?

using the compressoin release on a 100 mile enduro helps save your brakes from wearing out. all the guys in our shop that raced in the 70's did this to all their bikes.