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Ok, so I'm in the process of sorting my pilot jet…

…there are two types being sold for PHVA carbs.

Can anyone shed light on the difference? I'm confuzzled.

Yes, I can replace like for like… but it still leaves me wondering what the difference is, and why there are two types:

https://www.dellorto.co.uk/shop/dellorto-motorcycle-carburettors-parts/carburettor-parts/jets-needles-floats-calibrated-parts/16280-dellorto-idle-jet-phva/

https://www.dellorto.co.uk/shop/dellorto-car-carburettors-parts/parts/drla-parts/idle-power-jet/
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They are almost certainly NOT interchangeable. Believe the taller jet is the lower-speed of the two. The physics and hardware to atomize fuel at low quantities at low speed in the carb venturi are different than at high volume/speed.
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Juan_ORhea wrote:
They are almost certainly NOT interchangeable. Believe the taller jet is the lower-speed of the two. The physics and hardware to atomize fuel at low quantities at low speed in the carb venturi are different than at high volume/speed.
Thanks. 👍

Interesting - my carb came with a 38pj (the latter type, akin to a MJ).

Tried a 32pj today (the former type, with an atomiser built in). It fits (the threads for it were there, as well as space in the tube). It runs but not much success with it today (granted, I need a 36).

Main jets attach to an atomiser, save that you only change the jet and leave the atomiser alone - I find it odd that the pj on my carb had no such thing in the hole (but it ran fine).
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NSM? This is so annoying
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Molto Verboso
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Max6200 wrote:
NSM? This is so annoying
Oh, please. Step down from your fuel-injected ivory-tower high-horse and spend some time with us hoi polloi. Modern carbed Vespas have the same setup, with these two styles of jets in one carb.
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Juan_ORhea wrote:
Oh, please. Step down from your fuel-injected ivory-tower high-horse and spend some time with us hoi polloi. Modern carbed Vespas have the same setup, with these two styles of jets in one carb.
ROFL emoticon

Perfect answer. It made my day.
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The 11600 jet is a main or power jet on some carbs and a pilot or idle jet on other carbs. 16280 is the pilot jet on all PHVA carbs.
That's why the 11600 is available from 25-120. 25 is a pilot jet and 120 is a main jet.
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Motovista wrote:
The 11600 jet is a main or power jet on some carbs and a pilot or idle jet on other carbs. 16280 is the pilot jet on all PHVA carbs.
That's why the 11600 is available from 25-120. 25 is a pilot jet and 120 is a main jet.
Thanks. 😎

Any difference between the two in terms of how they might behave or should I just get the least expensive? The built-in emulsifier is intriguing.
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OscarSass wrote:
Thanks. 😎

Any difference between the two in terms of how they might behave or should I just get the least expensive? The built-in emulsifier is intriguing.
You should get the one that looks like the one you are trying to replace. KISS.
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