The Boxer engine

Text: Henk van Hoorn

After some 9 flights had been made the first engine (see "the present model") started to lose power gradually. In a former stage the big end play had been adjusted to narrowly which had led to some damage and severe scratches on both piston and cylinder led to loss of compresion and therefore loss of power.
Despite polishing the scratches and improvements made to the carburettor (adjustable fuel nozzle) the engine would not reach beyond 3050 RPM and flying a circuit proved impossible.

As a last measure the engine was equipped with an electronic ignition system. This did not yield the improvement we needed so now the engine is written off definitely. 

An intermediate step was the building of a new engine, this time with one dummy cylinder in a 'Boxer' layout. It is based on a 210 cc. Kawasaki power generator of 5 hp with magnet ignition.

Step 1:
Take the engine apart and clean all components.
Parts to be re-used: crankcase, cylinder, cylinderhead; crankshaft, piston, connecting rod, distribution train, valves, pushrods.

 

 

 

 

Step 2: 
Saw off the bottom of the crankcase.
Make a mounting plate to be welded to the crankcase.
Fit the parts to size.

 

 

 

 

 

 

Step 3: Welding of the crankcase; adding of extra mounting studs; fitting of inletflange to new position.

Step 4: Manufacturing of missing parts like: Engine mounting flange; adjustable mounting of ignition coil; bearing housings; propellor flanges.

Stap 5: Adapting of existing parts like: Magneto(fly)wheel ( stemmed from a smaller engine); crankshaft; distribution gear.

 

 

 

 

wpe4.jpg (29342 bytes)The engine, complete with dummy cylinder, ready for assembly.
(click the picture for an enlargement)

 

080927-02.jpg (248700 bytes)And here the engine is in its place, ready to perform the first (succesfull) circuit tests on 27-09-2008.