Choke plunger

[Diederik Hagen]

Dear fellow single Guzzisti,

I am doubting the functioning of the choke of my Galletto powered bike. It's got the well known VHB(22) carb. I've got the feeling that the plunger doesn't fully close the fuel supply. Could this little rubber seal have hardened and thus not closing the channel?

Do you know of any EU supplier?

BR Diederik

[Shaun Laughy]

Hello, Diederik.

Sorry, I don't know of a supplier for these (I'm new to Guzzi singles), but if this is a similar design to the VHB 29, you might be able to simply flip that seal over and use it for another several decades.

Cheers,

Shaun

[Paul Marx]

It does harden and not seal properly. Pick it out, turn it over and no need for a new one.

Paul

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[Don West]

You should be able to get replacement choke plungers from Eurocarb  Either cable operation or flip lever on top of the carb.  If the latter, be aware there are 2 different lengths available.  

https://www.dellorto.co.uk/product-category/dellorto-motorcycle-carburettors-parts/carburettor-parts/phbephb-parts/ 

Don  

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[Richard Harding]

This might be of use https://www.thisoldtractor.com/moto_guzzi_loopframe_carburetor_enricher_-choke-_plunger_-_seal_replacement.html

Also you could try https://www.dellorto.co.uk/ they have them for vhb carbs

Richard Harding

+44 7967 472264

www.linkedin.com/in/richardjharding

@richardjharding

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[steven s.]

From your photo, I don't see a spring between the plunger and the pot metal/aluminum cap. Is that spring present? It is required for pressure. This looks like average, but not excessive, wear on the rubber seal. The spring can also be removed, stretched by hand to about 8mm more length, and then it will exert more pressure against the air-hole. 

   As long as you have spring pressure and a touch of free-play in the cable, this plunger should seal.

Steven S.

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[guzz...@aol.com]

go to your hardware store in the plumbing section and size one up.......

Tim

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[Patrick Hayes]

On 4/12/26 14:18, 'steven s.' via Guzzi Singles wrote:
> As long as you have spring pressure *_and_* a touch of free-play in the
> cable,

Ditto on the inline spring. Should be in that picture.

Ditto on the free play for the control cable. When the system is slack
and the plunger is down, the outer cable sheath should be loose and free
and allow for about 2mm to 3mm of free motion before it begins pulling
on the interior plunger.


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Patrick Hayes
Fremont CA
Falcone-NT and SuperAlce
www.motohayes.com

[Diederik Hagen]

Hi all,

The spring is definitely present. The rubber didn't seem worn to me too. As you can't say for sure though and I found a revision set with ao plunger and spring I'll change it anyway. For the price of 20 euro fiddling trying to flip the rubber doesn't seem to make sense either :).

Thanks for your help.

Diederik

Op ma 13 apr 2026, 02:07 schreef 'Patrick Hayes' via Guzzi Singles <guzzi-...@googlegroups.com>:

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[RogerRowland]

Yes Guzzi bits UK I’ve bought them for T3 etc think they are the same never liked the design. To me it’s all or nothing not a gradual metered feed. 

Regards Roger Uk 

Sent from my iPhone

On 12 Apr 2026, at 22:18, 'steven s.' via Guzzi Singles <guzzi-...@googlegroups.com> wrote:



From your photo, I don't see a spring between the plunger and the pot metal/aluminum cap. Is that spring present? It is required for pressure. This looks like average, but not excessive, wear on the rubber seal. The spring can also be removed, stretched by hand to about 8mm more length, and then it will exert more pressure against the air-hole. 

   As long as you have spring pressure and a touch of free-play in the cable, this plunger should seal.

Steven S.

On Sunday, April 12, 2026 at 12:50:48 PM MDT, Diederik Hagen <ikdie...@gmail.com> wrote:

Dear fellow single Guzzisti,

I am doubting the functioning of the choke of my Galletto powered bike. It's got the well known VHB(22) carb. I've got the feeling that the plunger doesn't fully close the fuel supply. Could this little rubber seal have hardened and thus not closing the channel?

Do you know of any EU supplier?

BR Diederik

<1000033740.jpg>

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<1000033740.jpg>

[Diederik Hagen]

Didn't buy it in the UK because you silly guys didn't want to be part of the EU family anymore :). Now we need to pay silly taxes :(.

Op ma 13 apr 2026, 16:45 schreef 'RogerRowland' via Guzzi Singles <guzzi-...@googlegroups.com>:

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[Diederik Hagen]

Hi guys,

Being relatively new to Guzzi singles and the Dell Ortho VHB in particular I need your experience and thinking power.

My carb has been cleaned and treated with new gaskets and as of today a new choke plunger. For basic setting I gave the CO 2 full turns to open. Maybe I am wrong, but as I look at the carb, I see the choke plunger opening an extra air vent and venturi for gasoline. So if the plunger is up, the choke is on or open or however you want to call it. When starting my Mostro Guzzi I open the choke by lifting the plunger. 1 or 2 kicks is enough and the Mostro runs lovely. After some time, when engine is warm, I want to close the choke, so plunger goes down. Now the strangest thing happens: the revs go wild and up... What am I doing wrong?

BR Diederik 

Op ma 13 apr 2026, 17:04 schreef Diederik Hagen <ikdie...@gmail.com>:

[Rick Yamane]

Make sure the slide stop screw is backed out all the way and the slide closes completely. You should hear it snap shut. You should also have noticeable slack in the throttle cable.
A simple principle is for the engine to speed up it needs more air.

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[Andrew Nahum]

This may not be much help cos I’ve only had a VHB on a Ducati 450.   In my experience it doesn’t need much choke at all and you can close it almost as soon as you get a start.  

If it speeds up when you close the choke maybe it means it’s happier now and was too rich before.   So you can adjust the idle screw (slide height) and the idle mixture with choke closed.  

As far as I recall ‘choke off’ is with slack cable so plunger is dropped.  Am I right guys?

On 15 Apr 2026, at 19:27, Diederik Hagen <ikdie...@gmail.com> wrote:



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[pouma1954]

Nothing wrong. You're weakening the mixture. Set the carb up from A to Z.

Paul

Envoyé depuis mon appareil Galaxy

-------- Message d'origine --------

De : Diederik Hagen <ikdie...@gmail.com>

Date : 15/04/2026 20:27 (GMT+01:00)

À : guzzi-...@googlegroups.com

Objet : Re: [guzzi-singles] Choke plunger

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[pouma1954]

Of course since the plunger is shutting off a fuel supply.

The engine is accelerating because the mixture is weakened on the iddle jet.

Paul

Envoyé depuis mon appareil Galaxy

-------- Message d'origine --------

De : Andrew Nahum <andrew...@gmail.com>

Date : 15/04/2026 21:39 (GMT+01:00)

À : guzzi-...@googlegroups.com

Objet : Re: [guzzi-singles] Choke plunger

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[Paul Compton]

On Wed, 15 Apr 2026 at 21:09, pouma1954 <poum...@gmail.com> wrote:

> Of course since the plunger is shutting off a fuel supply.
> The engine is accelerating because the mixture is weakened on the iddle jet.

The plunger first uncovers the top of the starter jet and then opens
an air bypass channel to provide a fast idle. It's effectively an
auxiliary carburettor.

Especially if you have the flip up lever style control, rather than a
cable, this is an all or nothing operation; Air passage wide open and
jet uncovered, or both shut. The fast idle can be uncomfortably high.
On my Morini V-twins, it's usual to use only one starting lever,
unless it's very cold. Fast idle with just one lever is 3500rpm+ and
much higher with both. Some remote lever setups will give you some
degree of progression on the fast idle, but the air passage has to be
at least partially open to deliver any extra fuel.

If engine rpm is higher with the starter closed, then there is some
problem with the basic carb setup. When I rebuild VHB/VHBZ/VHBT carbs
(Z and T are just later versions with detail differences like
replaceable float needle seats), I set them up with about 0.5mm of
light coming in under the slide and the fuel mixture screw about two
turns out from seated.

Some people seem to be very good at putting the slide in backwards,
which results in a lot of revs if you manage to start it!

--
Paul Compton
www.paulcompton.co.uk (YouTube channel)

[Alan Comfort]

Correct. as to the slack cable being the running position and the taut cable is for cold starts. 

Remember that this is not a "choke" per se, but rather an enriching valve.

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[RICHARD YAMANE]

Still needs additional air for the engine speed to rise apreciably.

Rick Yamane
Importer of Vape/Powerdynamo ignition systems and Polisher of bikes at Motion Pro

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