Hi all,

Been lurking around a while gathering tons of much needed info as a newbie to kits, but thought i'd finally make a post (ask for help ).

I've fitted some ZX6R carbs to my pinto which was previously fitted with the standard Sierra Weber (2V?) and ESC electronics for the dizzy etc.

So far it has gone ok and it fires up and runs on choke fine until the engine begins to warm and then it just starts coughing and wheezing and any attempt at opening the throttle just kills the engine.

I'm just wondering if the sensors on the old inlet manifold are key for the timing and this could be the issue - I haven't yet connected the temperature sensor and haven't a clue what to do with the cable that fitted to the carbs stepper motor.

I was wondering if the temperature sensor could be the issue and any idea's if I can just tape up the stepper motor cable or do I need to connect/bypass/short any circuits on the connector? I'm thinking of fitting the temp sensor into a piece of metal tubing connected to the hose before it enters the inlet manifold connection.

Just for background, the manifold and carbs were supplied by Chester Sports Cars and have the jets drilled out ready for the pinto. I've fitted a low pressure electric pump under the fuel tank and have a filter king regulator in the engine bay turned down so the PSI should be about right for the carbs.

Thanks all

Check the diaphragms in the carb tops are properly sealed.

On some installations the auxilliary air circuit needs blanking, the middle drilling of the three on the filter side of the carbs iirc.

Try a little more static advance on the distributor...

Sounds like he has an electronic distributor and has no vac connection
We could do with some photos of carbs and distributor

Thanks, yeah its an electronic dizzy, a cable plugs in the side where the vac advance would normally be.

Assume this is controlled by the ESC module and the timing is set dependent on the sensors wired into the module. Just not sure which ones can be ditched or if I need to bodge something to get them working (such as the temperature sensor in the manifold coolant supply).

Sorry at work at the moment so can't get any pictures up, but will try and post some up later.

I was wondering whether to go down the megajolt route, but would like to try and sort this first if I can as no point spending more money if it will work fine as is

I can't help on the electronic ignition side of things, but I am running ZX6R carbs on my 1800 pinto with a Megajolt.
There is no need to block the air correctors on the ZX6rs, if you do it will go horrendously rich.

When it is warm does it cough and splutter at idle? If you rev up slowly does it cough and splutter? If you try and rve it quickly will it 'jump over' the rough band and run at high RPM but roughly? I had this problem and tried cleaning the carbs out by blowing them through - all looked clean but still wouldn't run. Spent ages (months!!) mucking around and eventually took all the jets out, soaked them in carb cleaner over night and the scum that came out was unbelievable, cleaned out carb passages at the same time. Has run beautifully since then!

As R1-pete mentioned check all the carb slides are lifting when you blip the throttle. Have you balanced the carbs? My pinto is very sensitive to the balance - get it spot on and you can balance a 20p piece on end on the cam cover

Yeah, I ran ZX6R carbs and the Aux Air doesn't want to be touched. It will run fine without blocking them. In an ideal world, you'd have a wideband on the car to help identify issues as you change parts. Sounds like its running very lean. Quick checklist I'd look for;

Did you adjust the idle setting for each carb?
Did you adjust the needles for each carb?
What pump are you using and at what PSI?
Are the slides opening with the throttle?

Thanks guys, from the above and reaing other posts of similar problems its sounding more and more that the idle mixture is out.

School boy error that I thought it would just work straight away - in their instructions Chester do say the idle may need adjusting, so almost certain thats the problem.

I thought i'd start with the basics tonight and have checked all the float bowls etc and cleaned the main jets etc. Will move onto the idle next.

If I can get it working to a basic level hopefully I can run it up for a rolling road session to sort out properly.

One float bowl might have a sligt leak from the seal but need to check and the diaphrams seem a little still, but the needles do move ok.

Managed to get the idle working fine on the zx6r carbs but now will stall as soon as any throttle is used - any ideas.

I've cleaned out the float bowls and replaced seals etc, checked the needle setting (circlip is on the middle notch) and the idle screw is about 2.5 turns out.

Fuel pump psi is approx. 4.5psi and I have a fuel king regulator turned right down to drop the psi further.

With choke on it starts and warms up fine (little bit of misting from the carbs) and then once the choke is knocked off will tick over fine, so I think the idle screws are about right.

As soon as any throttle is used it just splutters and dies

Not sure if its too lean or too rich - any pointers as to how to tell or where to tweak next?

Can't help with the carbs but to tell if the engine is running rich check the spark plugs, if black and sooty then it's rich if very white then it's weak

If it won't rev then it is likely to either be the pilot jets blocked or needles not lifting.

Have you soaked the pilots in carb cleaner overnight? I keep harping on about cleaning in carb cleaner but the holes in the pilots are tiny and despite blowing them out regularly it took me 3 months of terrible running and almost giving up on my zx6r carbs altogether before a soak in carb cleaner transformed them.

quote:

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Originally posted by davidimurray
If it won't rev then it is likely to either be the pilot jets blocked or needles not lifting.

Have you soaked the pilots in carb cleaner overnight? I keep harping on about cleaning in carb cleaner but the holes in the pilots are tiny and despite blowing them out regularly it took me 3 months of terrible running and almost giving up on my zx6r carbs altogether before a soak in carb cleaner transformed them.

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Have you done anything with the main jets? They will need enlarging for use on a car.

I run 1.6mm on my 2.0 Zetec with zx6r carbs.

Stu

I run 1.8 mains with .075mm air correction in my R1 s on Black Top.....

To get everything running , i.e. Under no load, then the standard jets and needle setting will be fine. When you come to use it under load you will prob need to open the mains upto 1.5 to 1.6 mm and raise the needles 1 or 2 grooves. Do not block the air correctors on the zx6rs - if you do then it will go stupidly rich.

With standard settings the engine should happily idle and rev up quickly and slowly cleanly without any lumps,misfires or hesitation off-load. If it doesn't then there is an issue, but it will not be main jet or needle height related.

Bike carbs need very little in the way of pressure, typically 1.5 psi max, you will struggle to get your regulator down to this and reliably maintain it. The effect of the pressure is to make you massively rich when you open throttle as the pressurised fuel is suck up by the Venturi effect.
I had the same problem,granted on a bike engine but that doesn't matter. You need a pump from a bike that self regulates at a lower pressure (all carb bikes use a similar pump)
Quick way to test before you change, if you can isolate your pump from running, let the pressure settle and see how it now behaves when you pick up the throttle?

This is something that I hear quite often but in my case, I run a small solid state pump with the regulator set at 2.5 psi and it runs 'perfect', though I suppose that a pump matched to the carbs is the ideal combination.....

quote:

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Originally posted by redturner
This is something that I hear quite often but in my case, I run a small solid state pump with the regulator set at 2.5 psi and it runs 'perfect', though I suppose that a pump matched to the carbs is the ideal combination.....

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