fit it in the reverse of how you removed it
The aim is to set the choke (butterfly) gap such that when the engine is at its coldest it leaves a gap along the barrel that is only small enough to accommodate a 3mm drill-bit and the fast idle cam can cause idle speed to rise to 2000 +/- 200 rpm.
* Remove the choke body to reveal the bi-metallic strip
* Open the throttle and position the fast idle cam screw on the highest step of the cam by turning it (make it just on the step)
* Push the pullrod on the choke pull-down diaphragm the furthest it could go in and check the gap left when the bi-metallic strip is turned to the ‘start’ position. Turn the screw that manages the pullrod in or out accordingly until pushing the pullrod furthest in will lead to a 3mm gap between the choke butterfly plate and the barrel, when the bi-metallic strip is turned to its ‘start’ position.
I've discovered that in warmer weather (say above 15C ambient) the choke flap may not be fully shut, and once you get up to about 20-25C ambient it will be quite well open. So do this test in cool conditions, maybe October-April (UK).
* Refit the choke body ensuring that it remains on the ‘start’ position when coldest.
* The position of the choke body can always be adjusted depending on seasons so that there is always optimum cold start engine speeds
Fast idle should also be adjusted hand in hand with the choke pull-down diaphragm but when the engine is warm and at normal operating temperature.
* Position the fast idle cam screw by turning it in or out to the second step of the fast idle cam and check that the fast idle speed is between the specified 2000 +/- 200 rpm for fast idle. Adjust as neccessary
Note
start position should look like this, and spring shut again if you push down on the front edge:
Choke "pulled down" when the engine is started
Then 3 to 5 secs later the flap should open to twice the distance
