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Pinto 2.0 running issues possibly carb?

Guest nickp

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Looking at the pics of the plugs the carbs are badly out of balance. 

For info when describing the cylinders 1 is the pulley end and 4 the gearbox end.

Fit a new fuel filter as Nigel advised, finish the changes to the ignition system and get the timing set spot on. If you're feeling confident pull the carbs off and removed the float bowls. Check the floats are free to move and that they seal the fuel inlet needle valves and also check the fuel jets are all clear. MAYBE fit a fuel regulator as bike carbs only need about 2psi fuel pressure. I used a facet cube pump which gave 3psi and had no problems without a regulator. 

The carbs then need setting up so all the butterflies open equally and at the same time and then balancing with a flow meter. The carb the throttle cable operates is the master and all the others should be set to match this one.

I see you're in Southport so it's not a bad run for you down to Chester where you'll find AB garage and Adrian there is kit car friendly and very good with carbs including bike carbs.

A B Garage

Unit 167B Castle Close/Manor Lane, Deeside CH5 3QX
01244 537701



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Plug colours do suggest its running rich, not greatly but differently in each cylinder. Are all the plugs the same type. 1 & 2 look as if they are running less rich or hotter than 3 & 4.

I think the carbs need a strip and clean, resetting of float chambers, checking  needle positions (might be the type of carbs that allow different needle length settings) and balancing carefully. If that doesn't sort it then I would be hunting a bike carb expert for advice.

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Change or bypass the fuel filter.

see if this has solved the problem.

i have a Malpassi filter king fuel pressure regulator with built in filter set to 1.5 psi Bike carbs are usually gravity fed so don’t need much pressure.

bike carbs have limited ways of tuning with out going to a rolling road however there are a few things you can do at home.

bike carbs have an idle adjuster that props open the butterfly’s a tad, it’s usually a cable with a ½” thumb wheel and the cable goes to the throttle stop, you can turn this to set an idle speed when the engine is warm.

Those carbs look like Mikuni’s and may have adjustable needles, you can access these by taking off the top plastic caps, remove long spring, pull out the slide be carful not to damage diaphragm, turn upside down and needle will fall out. If needle has 5 grooves in the top part, a circlip and a collar you can adjust the mid range fuel by shifting the clip position. Up = lean, down = richer.

To set idle air/mixture there are screws at the back of the fuel bowl underneath the carb outlet these may be under an alloy plug which needs to be carefully drilled out to access and are a real pain to adjust. I suggest you leave these alone for now and get back to us if all other suggestions have failed.

Ditto float levels which also affect fuelling.

Do you run an air filter? If not you will be running lean and idle will be a problem.

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Guest nickp

Thanks all, I have changed the leads, plugs, fuel filter (I had already bought it!), added filters on the carbs - it is idling better, but still struggling to start when hot.

After rooting around the engine bay, the carbs are Keihin VP: https://photos.app.goo.gl/5svSeTysd9So5EDJ9

I have still got to get into the fuel pump and get that part number!

@Snapperpaul I have ordered the Malpassi filter, should be here mid-week so will get it fitted by next weekend.

@steve in stockport @Longboarder I have booked in with AB Garage for mid-may, I don't feel confident enough to play with the carbs myself.

I also noticed the crank case breather is original and the end of the pipe hasn't been connected to anything so I'll be fitting an oil catcher.

Thanks again for all the pointers, I'll post back as I get through all the bits and pieces.

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After rooting around the engine bay, the carbs are Keihin VP

I’ve have literally just pulled a set of Keihin VP’s apart, needles are not adjustable so apart from jets, float level and the mixture screw there’s not a lot to change.

keep us posted on how the fuel regulator works for you

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Guest nickp


Fitted the new fuel filter/regulator after some simple tuning (2 x 1 quarter turns to increase pressure) the cutting out when hot stopped, and it started first time. Still a slight misfire, at this time I was putting it down to timing that will be sorted by AB Garage when they look over carbs and ignition etc.

This afternoon, I go to get a T piece and pipe from my local industrial gauges shop to hook it into the oil pressure gauge from the pressure sensor, drove there, stopped at my dads to show him how good it was running; even he was surprised. Fitted the T piece and oil gauge at the shop and drove back; again no problems.

Tonight, I get in it to just go for a drive with my son and I get a squeaking noise which sounds to be from the inlet, the idling is very lumpy, even when driving it is very lumpy. Then I'm about to pull up and I've lost hydraulics on my brakes. I had to increase the idle setting on the carb to stop it cutting out, and if you give it some poke there is a load of back firing and flames from the exhaust.

So, fix for the cutting out when hot: Fuel Reg/Filter, New plugs and leads

New symptoms:

  • No hydraulics on the brakes - consistent - brake pedal doesn't go to the floor, just ineffective braking. It'll be parked until I figure this out, I'll check over it tomorrow for leaks and the obvious.
  • Back fire with flames on lift off after some poke
  • Occasional Squeak even on consistent revs/running
Edited by nickp
updated detail on brake symptom
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Guest nickp
16 hours ago, richyb66 said:

Check the vacuum pipe from the inlet manifold to the brake servo. If it's leaking you'll get reduced braking effort and bad running. 

This was exactly the problem, the pipe fro

 inlet manifold was perished 


It’s back to “normal” I.e. needing a tune up, balancing and timing 

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nickp - I have a Robin Hood Sierra S7 (recently acquired) so I've been getting to grips with the Pinto engine - mine is only a 1.6l not a 2.0l but from what I understand they are all derivations of the same thing.  I managed to get hold of the Haynes Manual for the Ford Sierra doner car - it has been very worthwhile!

The no.1 cylinder is the one nearest the timing belt (front of the engine in your pics/vids) and the firing order is 1-3-4-2 if that helps.

I have had a very similar issue with the engine revs dropping if I floor the throttle - mine is on a Weber 32/36 DGV twin-choke carb.  It got to the stage that I could only keep the car running with the choke fully open, even with a new fuel filter element.  I took the decision to strip and re-build the carb - it was very worthwhile as there was an enormous amount of crap in all the places it shouldn't be.  Having refitted the overhauled carb, it runs a lot better than it did and the issue with the pick up on throttle demand has been significantly improved but not totally elminated.  I have purchased a new Powerspark electronic distributor, coil, leads and new plugs and will be fitting these in the next few weeks - I am hoping that this will prove to be the final part of the solution.

Your fuel filter does look like it could do with a change - with the paper element filters if there's enough crap in there they can collapse under hard acceleration and starve the carbs.  You might also find, as I did, that the inline fuel filter was a later addition and that enough crap had already got into the carbs to affect performance.  Also, given that there is effectively a carb per cylinder, there might be issues with the balance between the air/fuel mix but I must admit that I am not an expert on bike carbs.

Finally, having had a look at the images of your spark-plugs I would say they look pretty much OK - have a look at the guide in the attached picture which is extracted from the Haynes manual.  It might be worth gapping them just to make sure the electrode gaps are right - if they are Champion F7YCC the gap should be 0.8mm (0.032") or if they are RF7YC they should be 0.7mm (0.028").  Obviously I can't tell what type they are from the pics - I'm not that good!!


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  • 3 weeks later...
Guest nickp

Hi everyone.

So issues are fixed!

Here is a run down...

So fuel pressure regulator helped a bunch, new leads and spark plugs too.

I took it to a local guy who works on old cars (even back to ~1930's stuff). It ended up with:

  • a new battery (just to be safe).
  • Carbs cleaned in a ultrasonic cleaner, reassembled and balanced.
  • New coil
  • Head removed, two exhaust valves were slightly bend (1000th), others weren't seated properly.
  • New head gasket and bolts
  • new cover gasket
  • new timing belt
  • ignition timing done.

Now it runs perfect like a dream


Thanks for all the advice!


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