6 replies to this topic

[Tifferrobinson]

My garage told me I needed to replace the choke tube on my carb, but I am not entirely sure what that is. I assumed it was the tube through which the choke cable went through, but to be honest there seems to be nothing wrong with that. He says that it is getting caught and making the mixture too rich and damaging the jet which is why my mini shudders when accelerating but it doesn't look like it is getting caught at all. Any ideas?

[Bungle]

do they mean the dash pot ?

[Ethel]

You'll have difficulty finding a choke tube on an SU!

Maybe he means the jet bearing if it's a HS? Might just need a strip and clean, though it wouldn't effect the mixture intermittently, it'd just hold the choke on.


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[Asphalt]

Do they know SU carburrettors?

Overfueling for HS carbs:
- worn jet (oval were the needle goes in - look REAL close!)
- worn/stuck needle valve (needs to be 100% clean and spotless)
- sticking jet (if choke applied it goes down but not back)
- wrong setup

Overfueling for HIF carbs:
- worn jet (oval were the needle goes in - look REAL close!)
- worn/stuck needle valve (needs to be 100% clean and spotless)
- worn choke mechanism seal (one or two o-rings)
- sticking choke lever

I could imagine - if yours is a HIF type carb - one would call the choke-mechanismn a 'choke-tube'.

To determine which carb you have:

This is the HIF type:

[Internal float chamber]

This is the HS type:

[external float chamber]

To check the jet it is advisable to use a magnifying glas to look at.

If you have a HS carb, look at the carb and a mate pulls the choke,
you'll see how the jet moves down. it needs to return fully if the choke is pushed back in.
If it doesn't - put a bit(!) of oil on and consider buying a new jet & bearing in the near future.

Spluttering on acceleration could be a matter of underfueling as well... Do you have enough oil in the dashpot damper?
Unscrew the black plastic screw on top of the carb and look if there's oil inside.
If not, fill the inner tube up with some fresh engine oil.

Hope that helps.

Cheers,
Jan

Edited by Asphalt, 07 December 2008 - 04:35 PM.

[taffy1967]

A Mini City would have the HS4 carb as standard.

[Tifferrobinson]

Spluttering on acceleration could be a matter of underfueling as well... Do you have enough oil in the dashpot damper?
Unscrew the black plastic screw on top of the carb and look if there's oil inside.
If not, fill the inner tube up with some fresh engine oil.

Hope that helps.

Cheers,
Jan

Do you mean standard 20W50 tesco value engine oil? I thought it was meant to be special stuff for the dashpot. If so that seems the simplest option to begin with. Thanks for all the advice

[taffy1967]

Spluttering on acceleration could be a matter of underfueling as well... Do you have enough oil in the dashpot damper?
Unscrew the black plastic screw on top of the carb and look if there's oil inside.
If not, fill the inner tube up with some fresh engine oil.

Hope that helps.

Cheers,
Jan

Do you mean standard 20W50 tesco value engine oil? I thought it was meant to be special stuff for the dashpot. If so that seems the simplest option to begin with. Thanks for all the advice

No you want a thinner oil for the dashpot, so 10W/40 would do, or the specific carb oil that Burlen sells.