As the Corsair is going to need a bit of work, I got my Rover Wayfarer with Quattro written on it. It hasn't been used for a little while and didn't start. I cleaned the carby but had trouble reconnecting the throttle/governor spring. So now what happens is that the mower starts but you can't turn it off. Regardless of which way the lever sits there is no change in the revving. There is a spring which doesn't seem to do much and I wonder if that is at fault or whether I have re-assembled incorrectly. Have tried different ways to reconnect but no success. Any suggestions?
Tiger, I think we are going to need a photograph of your governor plate (the mechanism the speed control cable connects to) so we can see what you've done. I do not have any literature on the Quattro engine but Bruce, Joe Carroll, and some others will be very familiar with them. It sounds as if you may have just connected a governor spring incorrectly, or not connected it at all, so it should be very easy to fix.
The Throttle lever moves the governor assembly to open but trying to close has no effect. There doesn't seem to be enough tension (?) to move the assembly back.
So far Google is telling me that the document is not available. Why not try direct-posting the picture to this page (if the file is small) or Photobucket if it's bigger?
The picture does not show the right hand end of the spring.
My first question is aimed at finding out whether you have a problem with a misassembled governor, or you have damaged the speed control cable so it is not moving the speed control bell-crank on the governor. I've attached the B&S manual's diagram of a typical air vane governor. I don't know if the Quattro has an air vane on the flywheel as shown, or a centrifugal governor inside the crankcase, but the principle is the same. In the bottom center of the diagram you can see the speed control bell crank. The speed control cable attaches to that bell crank, just outside the picture at the bottom, and it moves the bell crank. Find whatever your engine uses as a speed control bell crank - in other words, the movable lever at the engine end of the speed control cable that runs from the handlebar control. Does that bell crank move back and forth smoothly when you adjust the speed control on the handlebar? If it does not, you have a kinked or otherwise messed-up control cable, and you need to fix it. If the speed control bell crank moves back and forth as it should, you have a governor malfunction, which you need to fix. Tell us which you have, and we can get into the detail of fixing it.
Here is a more complete picture. Although the throttle lever isn't that smooth, the real problem seems to be further down as there is no tension to activate the shutoff.
The control cable seems to be connected to the bell crank correctly, and so does the governor spring. What is the situation with the control cable outer's anchorage on the carburetor? This has to be correctly adjusted so that the bell crank moves reliably from its shut-off position (which shorts out the ignition when the handlebar control lever is in the stop engine position) to the maximum speed position (which extends the governor spring the correct amount for full governed speed).
Your description of what is wrong sounds rather like the situation that my own Victa was in when I bought it: the control cable outer's anchor at the carburetor end was completely missing, and as a result the position of the handlebar speed control had no consistent effect on anything, because the cable outer moved when the cable inner moved. Your lower cable outer anchor can't be seen in the picture - it would be right below the air cleaner sealing flange. Check that the upper cable anchor (inside the handlebar speed control) and the lower cable anchor (at the carburetor end) are both working properly, so the cable outer does not move relative to either the handlebar or the carburetor.
Thanks, grumpy. After a week or so of trying some things and not getting anywhere, I took this to the lawn mower shop where the guy said that the switch was faulty. He put on a second hand switch and now the mower is ok.