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Fuel tank vertical location

The tank center should be level or slightly below the center POINT of the carb. This holds for mounting at any angle. The center point of the carb is the reference. Visualize the fuel nozzle inside the carb, this is the location/height that matters.


Three blade props

Nothing wrong with using a three or even four bladed prop for break in, so long as it is in the right load range for the engine. All the engine sees is the load, and the only other thing the engine cares about while running is air flow for cooling. Doesn't matter how many blades are blowing the wind.


Piston Ring Fitting

Hold the piston firmly, a vise with padded jaws clamped on the rod works fine. Then hold the ring flat on top with the gap over the edge. Push one end of the ring down gently and feed it into the ring groove. Slowly work the rest of the ring down and into the groove.

Pumps on twins
ENTIRE SECTION REVISED 5/27/06.

Saito builds three mechanically different series twins.

First, the smallest have a single cam shaft. All four push rod tubes go to a single cam shaft chamber on the bottom of the crank case. This type has even firing intervals.

The second and third types use two cam shafts, one for each cylinder.

The second type has only one crank pin, the pistons move in the same direction at all times; while one is going up the other is coming down. As a result the crankcase volume is constant, there’s no pumping action for crankcase venting. As a result the acids from combustion leakage will accumulate in the case and destroy the bottom end of the engine unless the operator is religious about flushing and oiling the engine after operation. Not many people are, and the early odd-fire twins suffered because of this. The later odd-fire twins have an added scavenge pump for forced breathing of the case. The FA-90T and the FA-100T have a vane pump at the rear of the case, the FA-130T has a diaphragm pump driven by the number one cylinder cam. (Note from w8ye: My 100T has a diaphragm pump driven off the right intake cam lobe with a pressure line to the rear of the crankcase.)

The third type twin is, of course, even firing. They have two crank pins, the piston movement is opposite, giving them sufficient pumping action in the case with no added complexity.

So what do we do with the pumps where fuel tank pressure is concerned? Still talking about the odd-fire engines. The vane pumps and the early diaphragm pumps are internally ported to the crankcase, to use them for tank pressure is the same as using the vent on a single cylinder engine for pressure. The later diaphragm pumps have two nipples on the pump body, tank pressure set up is covered in the owner’s manuals as well as in these notes – look at the section on the FA-300TTDP.

The diaphragm pump on the FA-300TTDP is purely for tank pressure, again, the connections and adjustment are in the manual, and covered elsewhere in these notes.

Thanks to all who pointed out my errors in the earlier version of this section.


Pumps” on big block singles.

What Saito is now calling a pump uses two check valves in the back plate, other than the source of pressure the "Back plate valve" pump works exactly like the diaphragm pump version, it is connected and adjusted exactly the same. Check with Hobbsy, he recently got the back plate version as an option for his new FA-220.

What's wrong with it is the same reason you don't see many people using it. It's a royal bear to get set up properly. Consider the Perry pump, almost bolt it on and go, or the Cline and Iron Bay systems which ARE bolt on and go.