Vespa Running to Rich

[garystephen]

Hi can anyone give me some advice on my vespa px200 2006 plate it seems to be running to rich as the spark plug is black I have fitted a new spark plug and after a week its the same again so after reading up it seems that it is running rich can anyone help me in how to adjust so it will run properly and not to rich.

[ironsloth]

vespa.proboards.com/thread/6576/spark-plug

Take a read of that 👆

[garystephen]

I have a NGK BR6ES spark plug in my Vespa 200cc 2006 plate am hoping this is the correct one.

[phattanglo]

The Wasp performance website indicates that a number 6 plug is correct.
Yours is a resistor type plug hence the R but the std plug is a B6ES which is the same heat rating and the same thread length.
The PX200 uses a long reach plug
The only difference is the std plug doesn't have a resistor built in.
Have you had an opportunity to do a good long run on your scoot to get the plug up to full working temperature?

If you're doing fairly short runs with a lot of stopping and starting this may be the reason for the sooty plug, especially if your pilot jet is set too rich.

If you look at the body of your carb it should say either Dellorto or Spaco.

If it's Dellorto then the pilot screw should I think be about 1.5 turns out from fully screwed in.

If it's Spaco I think it's about 2.5 turns from fully screwed in as the thread is finer.

There's a good vid on youtube by mista freak moped that describes this process and what the throttle response should be like when the pilot jet is set to the correct position.

What you want is for the revs to rise quickly and cleanly when you blip the throttle and for the revs to come down and settle into a steady tickover within a second or two.

If the engine bogs and is reluctant to rev cleanly then your pilot is probably screwed out too far and is running too rich.

If your revs climb fairly quickly but take a long time to come back down to a tickover, then your pilot is probably screwed in too far and is running too lean.

From what you've described it sounds more likely to be too rich but I would just adjust the pilot jet and go for a run to start with.

[garystephen]

Hi phattanglo,

I bought a new NGK spark plug cap 5kΩ ceramic resistor so am wondering if I don't need the BR6ES spark plug and just the B6ES spark plug I know the new spark plug cap has a 5kΩ ceramic resistor in it.

[phattanglo]

Possibly there might be a slight difference in the spark but if the plug is gapped correctly there shouldn't be much in it.
My own experience showed the journey to work wasn't long enough for my PX125 on the std plug which I think was a number 7 so I use a number 6 which is a bit hotter and it seems to run better on my short commute but if I was doing a long run I would go back to a number 7.
I'll go out on a limb here and say it's your pilot jet that's a mile out unless a previous owner had a performance exhaust or barrel kit on and didn't go back to std jetting.
My apologies if I turn out to be talking complete Ball*cks.

I've just thought of something else you can check.

I once had exactly the same problem and it turned out to be very slight damage to the pilot jet thread in the carb body preventing the pilot jet screwing all the way in.

This meant when I thought the pilot jet was screwed completely in, it was actually a mile off so unknown to me when I thought the screw was 1 1/2 turns out it was actually on the verge of falling out.

This meant any more than a minute of standing at tickover in traffic would result in a plug that was black as coal and having to change the plug mid journey.

[garystephen]

Thank you again for your advice the vespa is standard 200cc engine with standard exhaust I have ordered two B6ES spark plugs and I have two BR6ES spark plugs along with this park plug cap has a 5kΩ ceramic resistor in it. I think I will install the B6ES spark plug as am thinking I have already got the spark plug cap with a resistor in it why would I need a resistor in the spark plug as-well. Am am going to try and find out the make of the carb and then take it from there.

If it's Dellorto then the pilot screw should I think be about 1.5 turns out from fully screwed in.

If it's Spaco I think it's about 2.5 turns from fully screwed in as the thread is finer.

Is there anyway in telling what jets I have in my carb?

Regards

Gary

[ironsloth]

Only way is to pull them out and read them. There usually is a lightly stamped number on the jets theirselves.

[ianmartin40]

I have a 03 plate px200 and it has a spaco carb, as far as i know dellorto had stopped making the SI carbs by then. To my knowledge 2003 was the last year of manufacture for the px200 as mine is one of the last ones made, a serie special.
You may have old stock, or perhaps a Ron Dealey special.
A standard set up is a Piaggio rubber cap with no resistor, and the small resistor on top of the plug that screws on, worth making sure air filter is clean, then check jet sizes, all fairly easy to do.

Ian

[garystephen]

Hi Ian martin,phattanglo

I have a px125 but it has had a 200cc engine fitted by the previous owner. I have had a play about with the carb today and its a Dellorto carb on it and I have screwed the pilot screw all the way in and turned it 1.5 turns out. The dellorto carb has numbers SI24.24E stamped on it. I have stripped the carb and gave it all a good clean out.