Originally Posted by
hsukaria
I am also concerned about engine spare parts over the next few years. I suppose for my 2-strokes, what will wear out are the bearings and rings (or piston/liner). Those are replaceable by other suppliers (except the piston/liner). Even the muffler and carb are replaceable with some adapter if they are damaged in a crash.
For 4-strokes, I see what you mean about unavailability of spare parts can shelf the engine. I see that Saito is adding gas versions of the glow engines while they reduce their glow engine lineup. Maybe going with gas Saitos is the way to go.
Most of the "gas" engine parts will interchange. The only difference is the intake manifold & the interface W/ the cylinder. Pistons, rods, even the Crankshafts will interchange W/the only difference being the locating pin for the prop hub on the "gas" crankshafts. On some of the smaller FG-11 gas engines the cylinders & intake manifold is the same, the FG-14 not so.
The FG (gas) multis use the 180 size cylinder bore W/smaller 120/150 valves on FA-300T & FA-450R3 bottom ends. Rods valve train, etc are all the same. In fact, there are only 2 valve train families in use on the currently available crop of medium/ large Saito engines. From the cam to the rockers, all valve train components are either FA-50 or FA-120 part #s. This is true of all gas or glow medium/large single cylinder & multi cylinder engines including the FA-220, FG-36 & FG-40
An interesting side development is that FG-57T or FG-84R3 piston can be utilized in an otherwise stock FA-180 to raise compression ratio to 10.75:1 & it is a straight bolt on affair. The compression height of the gas engine piston is .019 (.5mm) taller to compensate for the 1.1mm shorter 150 derived stroke in the multis. No clearance issues. All of the glow & gas engines using the 180 bore utilize the same piston ring. The FG-57T/FA-180 piston mod netted a 150-200 RPM improvement in power when tested against the stock 9.6:1 CR FA-180 running on CDI/glow fuel. If your FA-180 needs a piston, the $11.75 FG-84R3 piston will save you $$ & boost performance too.
Curiously the FG-57T piston is $47.49, the FG-84R3 is only $11.75. The only difference is the additional skirt clearance machined into the shirt bottom on the radial engine version. Either will work in an FA-180.