I am stripping down and servicing (including ultrasonic cleaning) a
Dellorto PHF36 carb for a local VMCC section member. All is going well
ready for a James May session with all new gaskets, o-rings and
accelerator pump diaphragm. Except the pump jet is reluctant to come out
of the holder. This was no bad thing when first dismantling as I think
the jet can get annoyingly stuck in the carb body sometimes.

I've already picked sweller's brains in a general way about the job ,
but thought a wider audience (including PipL) might have experience of
this specific issue. Don't want to use too much force.

The accelerator pump diaphragm and gasket were surprisingly easy to
tease from their location. The main jet holder and a couple of other
screw in bits were reluctant, but shock & unlock came to the rescue.

51 (Pump Jet Holder) and 7 (Pump Jet) on this diagram.
https://www.dellortoshop.com/drawings/dellorto_phf_carburetor_exploded_view_drawing.jpg

--
Moto Morini 2C/375, Moto Morini 2C/350
Gilera 175 Sport, Husqvarna 401 Svartpilen
"Do not adjust your mind, there is a fault in the reality"

Pete Fisher wrote:

> Except the pump jet is reluctant to come out of the holder. This was
> no bad thing when first dismantling as I think the jet can get
> annoyingly stuck in the carb body sometimes.

Do you need it come out? I'd probably leave it in place and hope the
ultrasound cleaning does its stuff - it may loosen it as well.

> Don't want to use too much force.

Whilst the metal is good quality the brass parts can be easily damaged.
Unsurprisingly.

> but shock & unlock came to the rescue.

Is that a method or some special release liquid/magic potion?

--
Simon

On Thursday, 1 December 2022 at 09:48:53 UTC, sweller wrote:
> Pete Fisher wrote:
>
> > Except the pump jet is reluctant to come out of the holder. This was
> > no bad thing when first dismantling as I think the jet can get
> > annoyingly stuck in the carb body sometimes.
> Do you need it come out? I'd probably leave it in place and hope the
> ultrasound cleaning does its stuff - it may loosen it as well.

Doesn't really need to come apart, but couldn't see why not. Both bits sparkly clean now.

> > Don't want to use too much force.
> Whilst the metal is good quality the brass parts can be easily damaged.
> Unsurprisingly.
> > but shock & unlock came to the rescue.
> Is that a method or some special release liquid/magic potion?
>

Penetrating/freezing aerosol. Even the differential contraction between brass and alloy seems to help - or perhaps it's placebo effect and I just used more force. I had to use a particularly well fitting bit and a t-bar to shift one.

--
Google Groups doesn't put in a sig

On 01/12/2022 09:48, sweller wrote:
> Pete Fisher wrote:
>
>> Except the pump jet is reluctant to come out of the holder. This was
>> no bad thing when first dismantling as I think the jet can get
>> annoyingly stuck in the carb body sometimes.
>
> Do you need it come out? I'd probably leave it in place and hope the
> ultrasound cleaning does its stuff - it may loosen it as well.
>
>
>> Don't want to use too much force.
>
> Whilst the metal is good quality the brass parts can be easily damaged.
> Unsurprisingly.
>
>
>> but shock & unlock came to the rescue.
>
> Is that a method or some special release liquid/magic potion?

Remember that zinc alloys can crumble with age, too.

Undoing it may help the process, rendering all your effort into a pile
of chunks and white powder.

--
Rusty Hinge
To err is human. To really foul things up requires a computer and the BOFH.

On Wed, 30 Nov 2022 19:56:50 +0000, Pete Fisher
<peter@ps-fisher.demon.co.uk> wrote:

>I am stripping down and servicing (including ultrasonic cleaning) a
>Dellorto PHF36 carb for a local VMCC section member. All is going well
>ready for a James May session with all new gaskets, o-rings and
>accelerator pump diaphragm. Except the pump jet is reluctant to come out
>of the holder. This was no bad thing when first dismantling as I think
>the jet can get annoyingly stuck in the carb body sometimes.
>
>I've already picked sweller's brains in a general way about the job ,
>but thought a wider audience (including PipL) might have experience of
>this specific issue. Don't want to use too much force.

Sorry, no experience of those ones.

--

-Pip

On 01/12/2022 18:38, RustyHinge wrote:
> On 01/12/2022 09:48, sweller wrote:
>> Pete Fisher wrote:
>>
>>> Except the pump jet is reluctant to come out of the holder. This was
>>> no bad thing when first dismantling as I think the jet can get
>>> annoyingly stuck in the carb body sometimes.
>>
>> Do you need it come out?  I'd probably leave it in place and hope the
>> ultrasound cleaning does its stuff - it may loosen it as well.
>>
>>
>>> Don't want to use too much force.
>>
>> Whilst the metal is good quality the brass parts can be easily damaged.
>> Unsurprisingly.
>>
>>> but shock & unlock came to the rescue.
>>
>> Is that a method or some special release liquid/magic potion?
>
> Remember that zinc alloys can crumble with age, too.
>
> Undoing it may help the process, rendering all your effort into a pile
> of chunks and white powder.
>

I've found Dellortos to be made of reasonably stern stuff in Mazac terms.

Ancient (well relatively) VHBs from mid 70's Morinis I possess seem
fairly crumble resistant. The suitable case for treatment referred to is
only late 80's ('Vintage' only means > 25 years old in this context). A
different can of worms which I won't dwell on.

I've done enough ultrasonic cleaning of carbs to know that it may strip
off the surface oxidation so well that they go white "before your very
eyes" if left damp and exposed to the air for any length of time.

--
Moto Morini 2C/375, Moto Morini 2C/350
Gilera 175 Sport, Husqvarna 401 Svartpilen
"Do not adjust your mind, there is a fault in the reality"

On 01/12/2022 18:41, Pipl wrote:
> On Wed, 30 Nov 2022 19:56:50 +0000, Pete Fisher
> <peter@ps-fisher.demon.co.uk> wrote:
>
>> I am stripping down and servicing (including ultrasonic cleaning) a
>> Dellorto PHF36 carb for a local VMCC section member. All is going well
>> ready for a James May session with all new gaskets, o-rings and
>> accelerator pump diaphragm. Except the pump jet is reluctant to come out
>> of the holder. This was no bad thing when first dismantling as I think
>> the jet can get annoyingly stuck in the carb body sometimes.
>>
>> I've already picked sweller's brains in a general way about the job ,
>> but thought a wider audience (including PipL) might have experience of
>> this specific issue. Don't want to use too much force.
>
> Sorry, no experience of those ones.
>
>

In fact, the two parts did come apart with a bit of twisting and persuasion.

All reassembled with new gaskets, o rings and pump diaphragm.

Possible smoking guns were that the idle mixture screw was missing its
washer and the throttle stop missing its o ring.

The former could lead to difficulty getting the right idle mixture and
'transition'. The latter wouldn't make much difference IME as my PHBs
operate and idle quite well without the o rings.

Proof of the pudding will be refitting to the machine - which is
awaiting some mods and replacements to make the task of
removing/refitting the carb easier.

--
Moto Morini 2C/375, Moto Morini 2C/350
Gilera 175 Sport, Husqvarna 401 Svartpilen
"Do not adjust your mind, there is a fault in the reality"