17 replies to this topic

[OllyD]

Hi guys. had to undo my mixture screw yesterday (right after a £200 tune! ) Turns out there was nothing even wrong with the carb, but it's running like a sack of spuds now. So, am I too lean or too rich? Here's the symptoms!

• Won't start without choke (first half inch of the choke has no effect)
• stinks of petrol
• judders and splutters- revs dip up and down
• brand new exhuast gone black as the night sky in a matter of mintes
• can't keep up with the accelerator- either judders, or lags in reaction to it.

Too me that seems too lean, but then why does it stink of petrol
Quick answers appreciated, I've got work at 4!

[mike998]

Hi guys. had to undo my mixture screw yesterday (right after a £200 tune! ) Turns out there was nothing even wrong with the carb, but it's running like a sack of spuds now. So, am I too lean or too rich? Here's the symptoms!

• Won't start without choke (first half inch of the choke has no effect)
• stinks of petrol
• judders and splutters- revs dip up and down
• brand new exhuast gone black as the night sky in a matter of mintes
• can't keep up with the accelerator- either judders, or lags in reaction to it.

Too me that seems too lean, but then why does it stink of petrol
Quick answers appreciated, I've got work at 4!

to be honist mate i think its too rich, the sootty stuff on the exhaust is due to unburned fuel, jus like if u were to take the plugs out u would see soot on it due to the same reason. but then im not sure because the idea of the choke is to let more fuel into the mixture than air and you said u have to have it on to start up.
my gues would still be too rich.

[OllyD]

bump, anyone else have any input?

[danwebster]

Any oil in the dashpot?

[OllyD]

I filled it up the tube in the centre of the dashpot and the space surrounding it (as per haynes, but when the piston pumped, it flowed down into the main chamber of the carb and dribbled out the butterfly. So i assumed I'd put too much in, as it stopped dribbling down when there was only enough to fill that central tube. I used 3 in 1
.

[Gizzum]

Black stuff = too rich. Slaken off until runnin at peak revs. Drop idle screw until suitable idle, then adjust mixture until peak revs again. Repeat first steps until you can adjust anymore. This will set the carb to run slightly lean so a quarter of a turn to rich will be good to run on until you get another RR session. If you were running too lean the addition of choke would make the engine run better.

P.S. better to run rich than lean

P.P.S. The back of my car is covered in sooty deposits!!

[OllyD]

Hi gizzum, thanks for the reply. Stupid question, but what do you mean by 'peak revs'?

Edited by OllyD, 12 June 2007 - 02:11 PM.

[Big_Adam]

OllyD, get a colurtune. Makes life simple then.

I'd also say too rich.

[Gizzum]

When you adjust the mixture the revs will rise and fall. Turn so that the cars is running at its highest... peak revs! Yeah, as Big A said get a colourtune from Halfrauds. Not that expensive, or do what I did and buy a gas analyser from Halfrauds. £75 but then yoou can see exactly what is happening!

[alexcrosse]

as soon as you take any plug out and look at it you will no.

black, too rich, lean it off
white, too lean, its going to explode.

[OllyD]

Hi guys, still having no luck.

Winding the screw all the way in to all the way out (and all quarter turns in between) is still producing no joy. The revs are quite erratic, and I've now found pressing the accelerator chokes the revs and kills the engine, unless tapped slightly in which case the revs can be raised rythmnically at which point they stick for a moment before slowly dropping.

She's coming dangerously close to finding herself burnt out for the insurance money!

[ROD]

She's coming dangerously close to finding herself burnt out for the insurance money!

Don't do it! pm me if you want to get shot,i could do with some spares.

[OllyD]

ha, I gest.

But if anyone can offer some help, I'd appreciate it!

[minidaves]

relapped valves on a non unleaded head?

dave

[OllyD]

It's an unleaded head, and the valves were re-lapped about 4 months ago.

To sum up:
From lean to rich and everything in between, it won't start without the choke half out. And even with the choke out, touching the accelerator kills the revs- engine dies.


I need this fixed asap, as i need to drive into my a-level on friday morning!

HELP!

Edited by OllyD, 13 June 2007 - 10:11 PM.