If you can't find one, then it's probably no longer available.
last time I looked 2 rings = 39-40m/l per min and plain face = 160cc & 170cc 45-47m/l per min or equivalents are available.
If you want a 4 ring = 40 - 42m/l per min buy the one closest 2 rings = 39-40m/l per min and if it runs slightly lean file the jet out with an oxy tip cleaner.
Part numbers, 7a 2 rings CR03655A / 7b 4 rings CR03685A / 7C 1 ring CR03696A / 7D plane face CR03522A
