Too far in the past to be able to check for definate now, but the FS1E forks I bought were defiantely not correct for my YL1. Same diameter stanchions fitted the YL1 yokes, but the gap for the wheel was too wide at the bottom requiring additional spacers making up. Rolling chassis for the YL1 was apparently largely the same as the concurrent 80cc single YG1F (when was the last time you saw one of those on the road ?) and not the FS1E.
I find it suprising that the AS1 would have had the same fork as a 50 - those things were pretty quick for a 125 & I would not have though the FS1E fork would have been up to the job