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Thread: rocket giotto evoluzione r - rotary pump tuning

  1. #1
    Join Date
    Jun 2011

    rocket giotto evoluzione r - rotary pump tuning

    Gene Cafe Coffee Roaster $850 - Free Beans Free Freight
    Hi all,

    Just purchased a Rocket Giotto Evo R HX machine, It's a rotary pump machine and i've never owned one before. I previously has a Isomac Tea with a vibration pump.
    the biggest difference i find between the a rotary and vib pump is (other than the noise difference) the volume of water it pushes out while not under pressure.

    With the Vib pump machine i can count to 10seconds, once i pull the grouphead leaver, before the coffee comes through the basket. Feels like a good time for pre-infusion and i always get good crema.

    With the rotary machine I don't get any pre-infusion time at all. Once i pull the group leaver the coffee comes through the basket straight away and it's not as easy to get good crema using the same coffee grind. (pulling at 9bar)

    Is it possible to turn down the volume of the rotary pump to slow down how fast the machine reaches 9bar to slow down the process a bit to add a bit of a pre-infusion time?

    Or am i getting it all wrong?

    thanks in advance

  2. #2
    Senior Member Lyrebird's Avatar
    Join Date
    Jun 2018
    I think your problem is more likely to be the grouphead valving than the pump. Pull the mushroom and check that the upper section of the group (esp the gicleur) is all the right way around.

    To answer your basic question: slowing down a rotary vane pump powered by an AC induction motor is possible but it's not easy.

  3. #3
    Join Date
    Jun 2011
    Hi Lyrebird,

    Sorry for the late reply. I just got back from holidays.
    Thanks for the info. I'll pull the mushroom off tonight and have a look. Do you think it would make a difference if i got a gicleur with a smaller orifice?


  4. #4
    Mal Dimal's Avatar
    Join Date
    Oct 2004
    Warwick, QLD
    Quote Originally Posted by Pawnii View Post
    Do you think it would make a difference if i got a gicleur with a smaller orifice?
    I'd follow Lb's advice first to see if that fixes the problem.
    Don't want to fiddle around too much with Gicleur sizings unless you know what you're doing. You may upset the entire characteristic of the brew circuit.


  5. #5
    Join Date
    May 2014
    And further Pawnii ....I'd follow Mal's advice who's following LB's ..... >giggled like a schoolgirl

    But seriously you give little if any back ground info...
    Such as Where are you Aust? or Int'nl?
    Was the machine purchased thru a reputable provider And did they Bench Test it?

    Even more to the point...if you go to your machine now (hot) and with no G/Handle in activate
    the Lever /Brew Group ....what happens? Water flows immediately.... Yes ?

    I would be concentrating on finding the best 'puck setup' to suit the machine, that holds up the initial
    flow (Pre-Infusion) to around 6-8sec (from a naked handle, 8 to maybe 10sec from a spouted handle,
    tho I reckon 10sec is bordering on too slow).

    Tell us further -
    Beans ?
    Age from day of roast?
    Grinder ?
    ** How did you arrive at the Correct Dose weight for the basket your using? (did you use the 5cent test ?)
    Tamper ...correctly matched to the basket?

    More directly what I'm getting at is the machine is flowing thru the G/Handle immediately your activating the lever
    due to insufficient resistance in the setup of your shot / puck. (aka 5cent test)
    Pls mark up your grinder where it is now and weigh your dose.
    Then establish the maximum puck height that will fit under your screen, once tamped and ready to lock in.
    Then tighten up the grind After you've run a shot as a current test.

    Don't forget taste everything as the metrics are only a guide to direct your next move.
    Remember consistency in gets consistency out.

    Report back how you go.
    Dimal likes this.

  6. #6
    Join Date
    Jun 2011
    Hi Coffeeguy,

    Thanks for the help.
    I'm not much of a pro when it comes to coffee.
    I've never considered looking into the detail of making coffee so much as to able to answer your questions.
    I've no idea what the 5 cent test is..but i'll google it now haha.

    I'll pull the mushroom off the grouphead and check it out first and report back.

    - grinder is a Rancillio Rocky
    - bean are from coffee snobs - Fiefy's Barista Blend roasted.
    - beans are maybe 1mths old roasted
    - tamper is not perfectly matched to basket

    sorry for the late replies. In holiday mode with family
    Dimal likes this.

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