What is the third character on this sign seen in Taipei?
What was below the sign? That is, what products did the store sell? It wouldn't be motorcycles?

The sign says: 不够机车, or in old script 不够機車. 機車 means engine, but in Taiwan more specifically motorcycle.

ㄐ + ㄧ in bopomofo is j + i, that is ji, which gives 机.