Silver Swallow Diesels

(aka Yin-Yan)


Name Yin-Yan Designer unknown
Type Compression ignition Capacity 1.49 and 2.47 cc
Production run unknown Country of Origin China
Photo by various Year of manufacture unknown



"This is engine we have made for you and is the engine you will use."

So says the translated instructions and who are we to say no? Jokes about the Command Economy, Communism, and aeromodelling by numbers aside, this is a nice little engine. The Silver Swallow originates in mainland China. It appeared in Western markets early in the 1980's in two capacities, 1.49cc and 2.47cc. The finish and fits on the early ones are simply superb. Later ones are variable. This picture shows a 2.47 Yin-Yan on the right, and a "watzit" on the left. Despite the striking simalarities, there is no known connection (engines and photo by Bert Streigler).

Both engines are similar in construction. They are plain bearing, 360 degree ported, compression ignition engines, similar to the early Taipans of the late 50's, or the Allbon Javalin before that. The steel liner is hardned and ground, screwing into a die-cast crankcase (with very fine engraving of Chinese pictograms and English text). The cast-iron piston has a conical crown with a fully floating wrist-pin. The con rod is fully machined aluminium. The cooling fins screw onto the cylinder liner and are generally anodized in gold, black, green and other colors, although I've seen examples of the 1.49 with plain aluminium finish. The needle/spraybar assembly is quite conventional with a single jet hole and a phospher-bronze clicker. The solder job of needle to thimble varies between well done and a cold blob. The prop driver to shaft is a rather deep cone onto a matching taper ground onto the shaft. The taper angle is too great to be self-locking. The red-head here (from the collection of Mr Van Richards-Smith) is a 1.49cc--although the box and instructions disagree on the capacity, with the former claiming only 1.47cc. The stated bore is 12.8mm, with stroke of 11.6mm. My calculator says this gives 1.4927cc, so you can't judge an engine by its box.

This one is an example of the 2.47cc engine. Apart from being bigger (duh), the head has straight-ish sides like the later Javalins. The 2.47 also has a venturi insert fitted. Published figures state the bore as 15mm, and stroke as 14mm, giving a capacity of 2.474cc. The photo does not do justice to the anodizing on this one which is a brilliant, highly reflective violet. Other colors seen on the 2.47's are gold, black and green. All engines are fitted with a simple compression lock. Notice the difference in the lock design from Bert's early model--serial number 0244--to my later example, which has no serial number. On the test bench, they've proven to be honest, easy starting engines with performance towards the top for the design type, as would be expected from the finish and fits.

The photo at the head of this page shows a 1.49 in it's box. Here are the two box styles known to exist. The first, containing a green-head 2.47, shows the more common packaging: a thin cardboard box around a styro-foam shell. Included are dual-language instructions (Chinese and Chinglish), a stamped "wrench", and set of mounting bolts. The other style is a two-piece affair of thicker cardboard, but smaller, with no foam insert and no wrench. There must have been warehouses full of these at some time as you are still likely to spot one today (try Carlson Engine Imports in the USA).




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