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MG Midget and Sprite Technical - update to 'what's happened?'

Car runs fine now, BUT needs full choke to start. Seems to indicate the mixture is too lean maybe, but I thought it would be too rich (if anything) after thorough cleaning of carbs/needles/jets. New fuel pump pumping well, checked discharge just before it enters carbs. Should I adjust the mixture or live with it?
aj robinson

Does it need full choke when hot? I recall your earlier post which said the plugs were light brown which seems about right. Did you change the position of the jets when you cleaned it all out?
Bob Beaumont

Havent tried it when hot yet, but I will. Have not changed the jet position as far as I know.
aj robinson

Nothing wrong with needing full choke to start a cold engine, that's standard MG starting procedure.

Dave
Dave Barrow

And it's not exactly what you'd call summer yet is it?
Lawrence Slater

True, but when I say 'full choke', I sometimes have to lift the choke levers at the carbs a bit further than the cable lifts them, and I didn't have to do that before. I've also noticed that when pulling the choke cable, the choke on the front carb is actuated more than the rear carb; is that normal?
aj robinson

Sounds like the adjustment of the carbs is needed. Both chokes should operate the to the same extent and the cable should pull them fully on.

The cams on the cross link between the two cabs are adjusted by slackening the 2BA nuts. The method is explained in the handbook or in the Haynes manuals.
Bob Beaumont

Thanks Bob, I will look into it. maybe I've accidentally moved something whilst cleaning.
aj robinson

Bo**ocks!
Back to square 1 because it started this morning but kept cutting out almost immediately. Now it won't start.
Bite the bullet and strip the carbs completely maybe?
aj robinson

No not yet... if its carbs related, its probably going to be 1 of 2

float needle and seat in the float chamber is actting up, ethanol fuel is a bit#ch to live and deal with.

The jet is not adjusted properly compared to the height of the float chamber seat... (tip... its to high)

If its not 1 those two and an exhaust valve is not sticking, then its most likly going to be electric

When the engine dies... what does the tach needle do, is it real gittery and swingy before it dies, or is the needle smooth and just gentwlly fades away as the engine dies

A last thought, but not likely based on your above comments is a vacume leak

Most importantly... avoid the temptation of randomly replacing parts... that just adds to the confusion, work the problem, not your imagination

Prop
Prop and the Blackhole Midget

Opps, just rereading... a vacume leak is a good possiablity

I think you may need a full tune adjustments

Start with the valve lash, then carbs, then ignition, then repeat the process to make sure everything is as it should be

Prop
Prop and the Blackhole Midget

Exhaust valve sticking is interesting; could that account for the change in exhaust note I observed previoiusly?
aj robinson

Sorry aj

I can not say, ive only read about sticking exhaust valves...ot actually seen one

Im ""guessing"" the outlaw tune would sour a bit

Prop
Prop and the Blackhole Midget

Ok, back again!
Checked valve clearances and then double checked to make sure all ok (12 thou)
Noticed spark plugs were black and sooty now, so cleaned up, checked gaps good spark.
Car started pretty well but a bit rough. Noticed that the front carb piston hardly lifts at low revs compared to the rear, but when revved hard engine sounds clean and carb pistons seem to lift in unison.
Front carb piston lifts smooth by hand. So, front carb needle valve maybe?
Any advice gratefully received!
aj robinson

Sounds like the carbs need balancing. Both pistons should lift the same. Also check for any air leaks around the inlet manifold.

Bob Beaumont

Thanks Bob
aj robinson

I agree with bob,

Most likely needs carb balancing or there is a vacume leak

Prop
Prop and the Blackhole Midget

This thread was discussed between 06/05/2015 and 13/05/2015

MG Midget and Sprite Technical index

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