For anyone travelling the same path…
Tested injector out of the cylinder and achieved a good fine mist, with what appears to be a fair level of control as the rack is gently moved…a few mm make a notable difference.
I placed a tie-wrap around the governor bob weights, re-assembled and fired up. We could then play with the throttle and rack without the governor adding constant adjustment. An ‘interesting’ and somewhat risky stratergy but we managed to get a fair level of ‘manual’ control but could only get a lowest rpm of around 1100. At least we now believe the injector and pump to be functioning.
It was noted that the bushing around the ‘excess’ fuel plunger was wound a fair way in. The internal end of the plunger is tapered, the throttle rests against the plunger when it is fully home.
Due this taper, by adjusting the bushing and the plunger depth, you can adjust the maximum throttle and max fuel for normal running.
I had to wind the bushing out..or else the throttle would always be pushed to far back and the engine would stop.
There is also a link between the throttle linkage and the rack. The length of this determines the sweep of the rack in relation to the throttle. Whilst an end to end length of 72mm for the link has been tried…I finally found a much shorter length of 70mm allowed my throttle and governor assemble to sweep the fuel pumps rack across what seems to be the correct range. Through Cut-off –> low fuel –> full fuel –> excess fuel positions.
(given basic no load testing so far).
I spun the governor up with a drill and noted the inconsistant bob weight behaviour. I was fully stripped down and cleaned. It now operates far more smoothly. With the governor and housing assembled, a spring balance can be placed on the ball of the throttle arm. Pulling past the governor, a force of around 0.7Kg was needed for the slightest movement of the bob weights and 1.8 to 2 KG of force for the bob weights to be pulled fully out.
This is just a ‘hobby’ method of measuring the bob springs and setting my starting point.
In practice the springs were adjusted a turn at a time, governeor fitted and engine started. This was repeated many times to find a good overall setting to give an idle of roughly 700RPM and a fast running around 2000.
Also, there is the access plug allowing the linkage to the popped on-off the throttle arm, if this is left off during engine running. Given a constant throttle possition you can observe how much the governor is driving the fueling, its not easy to explain but worth observing as you are trying to characterise the systems behaviour during run-ups.
I doubt the settings are ideal but until I sort the clutch and get some load on it…its a good starting point.
Highly unlikley its the end of this process but its a darn good start. 🙂
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