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Jaime Quevedo Burlingame, CA jqueved0@pacbell.net 5/11/2009

Mastiff engine

I’ve been working in the Mastiff engine for quite some time, got it to pop couple of times and then decided to dis-assemble, clean and do some final adjustments.
Now will proceed to re-assemble and get it running again.

Engine is an L.C. Mason design from 1973.
Engine specifications:
Number of cylinders:                     4
Capacity :                                             25cc
Bore x Stroke:                                   3/4" x 7/8"
Valve diameters IN/EX:                 5/16”
Horizontally Opposed                    4 Cylinder
Side Valve
4-Stroke,
Spark Ignition :                                  ¼ “ x 32 TPI plugs
Water Cooled with pumped Lubrication
The Mastiff stands 6 ½" tall, 8 ¾" long and 7 ½" wide

Minor changes to original design made were :
Ignition, CDI with Hall effect to replace contact points.
Lubrication, fully drilled crankshaft Vs original part drilled crank, for improved lubrication.
Camshaft was built in a single piece hardened and ground Vs original independent cams fixed in a shaft with Loctite or pins.