16 replies to this topic

[kjbenja]

Model:Mayfair
Year:1988

Rev's fluctuate between 500 and 1200 rpm.

Recently I had a overheating problem and the RAC dude replaced the thermostat.

Job done, then I asked him about the running issue.

He had a look and said the needle was bent but set it up best he could.

Can anyone tell me how to change the needle or is it complicated?

It runs pants and isn't too keen to start in the mornings without any choke.

I am a mechanical dunce

Please help !!!

Cheers

Keith

[dklawson]

I have never had any dealings with an RAC, AA, or the American equivalent the AAA dude. However, on this board I have NEVER heard of one correctly diagnosing a Mini related problem. I'm sure there are exceptions but I would not spend money based solely on what the RAC agent told you.

Some carbs use needles that are intentionally spring biased to the side. He may have mistaken this for a bent needle. Tell us what carb your car has and I'm sure someone here can offer some comments on tuning. In general, if you're going to attempt this yourself you should start by reading Haynes or the appropriate section of the SU tuning manual.

Lastly, I don't know why people are surprised when you need to use the choke to start an engine. If it wasn't needed, it wouldn't be on the carb. Contrary to what many think, the choke isn't exclusively for winter use. Regardless, once you've looked carefully at the Haynes manual, start by setting the valve clearances, do an electrical/ignition tuning, then... if necessary move on to the carb settings. Once you've worked stepwise through a tune up (in the order I stated above) I suspect you'll need less choke and that you'll be happy with how the car is running.

[kjbenja]

The carb is a SU HS4 as the car is a 1988 with a standard 998cc engine.

Any help on tuning would be appreciated if not a bent needle.

[998dave]

It's a five minute job to check the needle, and maybe one minurte more to change it.

Remove the air filter, (if standard), by undoing two butterfly bolts.
On the top of the carb there's the dashpot cover (big dome thing), secured with three screws, undo these and gently lift the dashpot cover off.
Next theres what looks like a metal cylinder, lift this and it should come out with the needle attached, check needle.

To remove needle there's a small grub screw in the side of this cylinder, loosen, withdraw needle, replace if necessary.

For other tuning, it may be ignition is worn, or timing out, dirty air filter or indeed wrongly set fuelling.

[kjbenja]

Thanks 998Dave

[kjbenja]

Hey I have managed to take the carb apart using the guide by Dave998 written above but the needle wont pull out the bottom.

How do I remove the needle itself?

What needle do I need to buy to replace it and where can I get it from? (halfords?)

[Jupitus]

Hey I have managed to take the carb apart using the guide by Dave998 written above but the needle wont pull out the bottom.

How do I remove the needle itself?

What needle do I need to buy to replace it and where can I get it from? (halfords?)

On the side of the piston you should see a screw which goes through the piston and secures the needle... undo it!

[Ethel]

An 88 car should have a bias needle as DK mentioned. you'd have to fully remove the grub screw and remove the needle seat along with the needle.

[Jammy]

Also, check the jet that sticks out the bottom of the carb, and is sprung up and down. Not uncommon for this part of the carb to get bent given its prone position, and lead to an un-smooth rise through the revs.

[kjbenja]

Hey I have managed to take the carb apart using the guide by Dave998 written above but the needle wont pull out the bottom.

How do I remove the needle itself?

What needle do I need to buy to replace it and where can I get it from? (halfords?)

On the side of the piston you should see a screw which goes through the piston and secures the needle... undo it!

I have undone the screw off the side and the needle and a grey thing it is in moves up and down but wont come out freely.

Do I need to use pliers or do I tip it upside down to get it out?

[kjbenja]

An 88 car should have a bias needle as DK mentioned. you'd have to fully remove the grub screw and remove the needle seat along with the needle.

I have undone the screw

And how do I remove them both?

[Ethel]

If you can get the grey bit to stick out a bit you could gently persuade it free with pliers. You may also be able to lever it from through the grub screw hole.

Jammy made a particularly good point - it's nigh on impossible to bend a needle unless you bend it inside the jet by batting it against the bulkhead.

[kjbenja]

If you can get the grey bit to stick out a bit you could gently persuade it free with pliers. You may also be able to lever it from through the grub screw hole.

Jammy made a particularly good point - it's nigh on impossible to bend a needle unless you bend it inside the jet by batting it against the bulkhead.

I know the car had a front end shunt a few years ago would that bend it?

When I look strait up at the needle it sits slightly to one side of the grey section.

All this help is much appreciated its just very frustrating as it doesnt pickup when changing gear and the revs fluctuate.

[Ethel]

The needle is supposed to sit to one side but should move easily. As long as the actual needle itself is straight, it should be ok. Since you've got it partly stripped you could do a drop test.

most of his vids are worth watching.

[kjbenja]

I shall watch in the morning as cant access at work.

Assuming all is OK what else could be causing my problem?

When I blip the throttle it tries to die unless I am very gradual with the pedal.