Choke return

[Rosbif]

I have a small problem, not even a problem really more an inconvenience, with the choke return.

If I pull the choke out only 2 - 3 cm it will return correctly when the knob is pushed back. However if I get carried away and pull it out fully it doesn't return correctly and I have to lift the bonnet and turn the arm by hand on the carb.

Is this normal? Is the return spring in need of replacement? Does the return mechanism need 'loosening' up a bit?

I have thought of fitting a clamp of some type on the cable so that it can't be pulled too far but this seems more like bodge than a cure.

Thanks for any thoughts you have.

[Bitumen Boy]

It's not normal, or at least it shouldn't be! Try a bit of lubrication and fiddling at first. 

[aleksandar]

Hello ‘Rosbif’, if it helps please try the following;

SU HS4 carb

Slacken/disconnect choke cable at choke cam

move cable so there is no interaction when choke cam operated by hand

Operate choke cam to full open position

let go and the cam should spring back to ‘choke closed’ position.

What you are trying to assertion is if the jet is sticking/binding, and if it is, then remove clean and realign. If it is not sticking then does the choke cam spring work correctly, ie the choke cam springs to the closed position, if not make sure spring not broke or fitted incorrectly.

Then operate choke cable independent of the carb. The reason is to find out if the cable is jamming inside the ‘choke cable outer’.

You should find the problem from this procedure, if not then I am flumuxed.

The above procedure only works in part for the Stomberg as you can only see if the operation of the cam open and closed, and whether the choke cam springs back to the closed position when released. But you can check whether cable sticking or not.

[marktheherald]

I have just sorted this problem out on my 1500 engine (twin Strombergs) in the Herald project...  The outer cable was kaput, stretching as I pushed the knob in.  New cable, problem sorted.

 The only downside is a mismatch in the knob position, (sitting at about 5 past 7...) Purchased from a major Triumph parts dealer.

[Rosbif]

Thanks guys, I'll try and slot this work in - weather & gardening permitting 😎 Well unless I opt to drive it rather than tinker, as if I would

[Rosbif]

Quoted from Rosbif-

Thanks guys, I'll try and slot this work in - weather & gardening permitting 😎 Well unless I opt to drive it rather than tinker, as if I would

Ok so I did go out in it this morning, grass too wet to mow and mower needs servicing so no choice 😳.

This afternoon looked at the choke return and followed the tips you guys gave me.

Once the grub screw was slacked allowing the cable to move without actioning the choke I was able to confirm that the cable moved freely and the return spring was fine as well.

Gave the assembly a squirt of cleaner, tightened the grub screw - no improvement.

On looking more carefully I noticed that when the choke was in the full on position the inner cable that extended beyond the grub screw was bent slightly towards the operating arm and it was this that was causing it to block. Quick bend in opposite direction and fixed.

[marktheherald]

Well done!

 You wouldn't enjoy fitting a new cable anyway...  ET fingers needed.

[Rosbif]

Quoted from marktheherald-

Well done!

 You wouldn't enjoy fitting a new cable anyway...  ET fingers needed.

Yes I can imagine it would require triple jointed arms and 8 fingers.

Always a sense of relief when potential problems turn out just to be a simple fix. 😆

Thanks again for the help on this forum - worth its weight in 20/50 engine oil.