SU choke lever

[Richardtr3a]

I have been checking my choke levers on my 1958 TR3A and I need some help.  There seem to be many different shapes. Burlen were helpful but did not answer my main problem. The brass choke lever pivots and has a spring at one end. The other end is connected to the cable. When it is pulled the lever pivots and moves the jet down. Once the engine is started the spring pulls the lever back to normal position as long as you have removed the ST clothes peg. The connections are made with pins and the hole for the pivot is much too big which makes it a very loose and inaccurate choke lever. 

It is working well and the carbs were overhauled by a specialist many years ago. My two levers look like the H4 AUC 1022  and the pivot hole is oversize.  Has any one else had this type of problem ?  At this stage I may need to get two bushes made up. 

Tomorrow I will remove the rear lever and take some measurements. Any advice would be very useful.

Thanks Richard & B

[Drewmotty]

The holes are supposed to be oversized. It’s a lost motion mechanism. 

[Richardtr3a]

Thanks for the reply. I am researching the "lost motion" mechanism and I will leave the carbs alone for the moment. What do other owners do when overhauling the SUs . ? 

Friday is a TR local club lunch meeting so we will be having some technical discussions. I need some more instructions from TR3 owners who have answers to my SU dilemma.

Thanks Richard & B

[RobH]

45 minutes ago, Richardtr3a said:

I am researching the "lost motion" mechanism

It's quite simple Richard - it just means there is slack in the system so the springs can raise the jets fully without restriction from the cable.  If there was no slack, every small movement of the cable will also move the levers.  (This is really only necessary because the cable inner is a semi-rigid wire rather than a braided cable as on later carbs, which itself can be left slack.) 

[Richardtr3a]

Thanks Rob,

I now understand the loose throttle lever issue. My cable inner is a braided cable and is located near the speedometer to allow for a straight run, instead of round the heater. I only use the choke on the front carb and there is an extra spring which runs horizontally fixed on to the body and helps it return to normal. The spring on the lever was not always pulling hard enough.

I will leave it all alone for the moment.

Thanks Richard & B