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MG Midget and Sprite Technical - Rich Running and Choke Issue

Hi Guys

A couple of issues on the midget front.

Firstly, the car is running rather rich, black splatters are left on the ground at the rear of the car suggesting rich running, whats the best way to fix this? This leads to my second point.

Secondly, the choke cable does not feel smooth, when the leaver is pulled it sounds and feels like the cable is dragging, the choke knob originally did not go all the way back and stuck out 3mm or so but it goes back properly now.

Thoughts?

Rylan
R Williams

First sort out the action of the choke cable

""black splatters are left on the ground at the rear of the car suggesting rich running""

Not sure that is the case who told you that?

What that is caused by is moisture in the exhaust being forced out on start up and collecting carbon on the way.

Once you have sorted the choke then set the carbs up correctly and happy motoring.
Bob Turbo Midget England

Thanks Bob for the insight.... I had never considard that the black powder on the ground was as you discribed... Id always thought it was a source of a rich tuned engine as well

Thanks for the heads up

Prop
Prop and the Blackhole Midget

I have always thought the splatters were the sign of a rich running engine, I may be wrong then in that case. It does however sound a little rough.

The choke is something that I think may be causing the slightly rough/rich running as when I got it back from the MOT the choke knob would not return fully, if you pushed it and held it in it would stay in. When you let go it would move out slightly and give the catchy feeling I described when pulled.

It may be worth going for a long drive then and seeing what difference that makes to the deposits from the exhaust.

Rylan
R Williams

Ryan,
Push the choke in as far as it will go and stay put.
Then go and take a look at the other end, at the carb. Has the choke mechanism turned as far as it will go and properly against its stop? If it has, then you may wish to adjust the cable length so that the control knob is fully home - but that is just for neatness sake.
If the choke lever isn't being pushed up against its stop, even though there is still potential for movement in the cable, then find out what is stopping it.
Guy Weller

3mm slack at the choke knob in itself is fine as long as you can push it fully home and it stays there

the sound of something dragging is more likely to possibly be the fault
Nigel Atkins


Hello Rylan - I've met you at MASC Kent meets - 1 due this Sunday.

A rebuild and/or tune might do it. i'm happy to bring along & give you my SU tuning guide this Sunday - I don't use it now I run a single HF4.

Gavin.
Gavin Rowles

Rylan,

Hope this helps..
http://www.bmcno.org/manuals/Tuning SU Carburetters.pdf
Pete Ottewell

Hi Guys

It turns out that the rich running was caused by one of the jets not returning as the springs had snapped.

I am going to order replacements from moss, I am a bit confused though as to what the kit contains!

Rylan
R Williams

This thread was discussed between 17/06/2012 and 21/06/2012

MG Midget and Sprite Technical index

This thread is from the archive. The Live MG Midget and Sprite Technical BBS is active now.