ORIGINAL: Lou Crane
Mike,
Can't say I'm familiar with the Silver Swallow 1.5, as such, but I have a pair of Jin Sheng 1.5s from the same factory. The more recent Silver Swallow and CS engines seem a bit prettier, but still about as useful as the SS or JS earlier editions.

To sum up: they work, about as claimed in the instruction sheets. If you need something else, look elsewhere. The Silver Swallow 2.5cc (actually claimed as 2.47cc) engines worked, but were not exceptional either way - bad or good - but were dependable.