Atco Commodore B20 - Carburretor Settings

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timsoles
KG Regular
Posts: 3
Joined: Fri Jun 12, 2009 3:42 pm

I recently purchased this machine as a non-runner. The previous owner thought the problem was the ignition coil, and he was right. The new ignition module cost a cool £80.00!

The machine appears in very good condition but had been unused for several years, so I had to remove and clean the carb to clear the petrol residue. The carb itself appears in good condition, although I had to replace the float needle to stop the carb flooding.

The engine now fires up, but I foolishly forget to check the various settings before dismantling the carb, so I need some guidance on the basic settings, and any tips that will help me to get it running smoothly.

It's a Dellorto carb, with the main jet protruding through the bottom of the float chamber casing.

I think I am right in saying that there are 3 screws to adjust: the tickover speed, the idling richness, and the main jet. To get me going, I need to know the approximate number and turns for each screw, and is there a correct procedure to follow?

I hope to get it properly running so I can get the lawn cut before it rains this weekend!

Tim
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Clive.
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Joined: Thu Nov 24, 2005 5:01 pm
Location: East Lincolnshire.
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Hello Tim,
Some Dellorto carbs on these mowers had an adjustable main jet retro fitted to help with some running problems that afflicted some early A114 engines..
By your description it does sound like yours has this adjustable jet conversion...as if it was as standard it would have just a brass hexagon "nut" under the carb to secure the bowl and then the main jet was fixed size of the internal central tube....with sole adjustment by the idle mixture on the carb side.

I do have some further info and will be in touch via the forums pm...

Clive.
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