How the S01A-9BAR Handled the Elusive Kirkland Ethiopia Light Roast

The Problem: Why Light Roasts "Break" Most Machines

Light roasts from high altitudes (like Ethiopia) are physically denser and less porous. On a standard pump machine, or many other popular manual espresso machine, they often lead to. Common problems are:

• Thermal: The temperature is not high enough for this bean. The water isn't hot enough to extract sugars, leading to a "sour/light grassy" shot. Many manual espresso machine is lacking here.
• The Pressure: If the grind isn't perfect, very common, the pump can't maintain pressure, resulting in a thin 20-second shot -- too light. It is not a medium or dark roast, it is a Light Roast. You need a finer grind size here - dealing with a balance act: slower flow rate and maintaining the pressure you want.
• The Long Extraction Time: This beans need to have a long extraction time and with a stable high enough pressure with a slow flow rate. The other end of the balance act on the resistance - the pressure.

The S01A-9BAR Solution: "Manual Overrides"

First, I did made a bad shot in the morning. What happened was that I did pay attention on the "light roast" which normally require a higher temperature for extraction.  I did not prepared in the missed shot. I also did not maintain a high pressure. And another wrong move, I did it too short in extraction time, 22 seconds. Okay, the second shot, I need to think and do it with the right moves. In this shot I did, I intentionally used a "coarse" grind size (medium-roast setting, I know it is fine with this machine) to start with for the shot. It did good, all due to the correct handling using three key techniques, as it is part of the machine features:

1. Temperature Control - The Thermal Max Preheat: Unlike machines with fixed PID loops, the S01A allows for a deep manual preheat. You do need to waste one more cup of hot water for the preheat. To maximize the starting temperature. For this bean, I pushed the heat to the limit to ensure the thermal mass, hot water for jacketing the pressure tube, which could "crack" the dense bean structure. I do need a temperature like 94C to 95C to start with.
2. Flow Control - Ball-Valve Flow for Timing and Duration: When the grind didn't provide enough resistance for a 9-bar push, I used the Ball Valve to restrict the flow. Open a tiny bit and then allow the flow to go very slowly. This manually maintained the high pressure needed for a slow, 50-second extraction.
3. Maintaining the Pressure: The ball valve controls the flow and also you can maintain the high pressure to the point you need. No readings, but the hand press on the piston is at a good hard press.
4. Automatic French-Press Style Action - The "Mid-Stage Infusion": Halfway through, I pulled the piston to introduce fresh boiling water, I do need more extraction —essentially a secondary "French-Press" soak. This kept the temperature high and the extraction moving. The extra soaking help to break through more on the Light Roast, hard to extract problem with this Kirkland Ethiopia Bean.

The Hardware - Good Filters: The 35x5mm, 35x3mm, 34x3.5 mm Filters

The filters help to reduce channeling. Not sure it is a factor in this "Light Roast" handling.

Result One (missed) : I did say, "What! What happened!" The flavor was so light. Almost like it was just sourness. Yes, it is a light roast -- remember, it is the Ethiopia Light Roast. I need to pay more attention.  And that is why I make the second shot. I know the machine can handle it.

Result Two (all good): A rich, aromatic latte with full body and deep citrus notes. Yes, it can be done with S01A-9BAR (or S01B-9Bar). With today's missed shot, with understanding on the reasons, I do think, most of the manual espresso machine out in the market would not be able to pull a good shot on this Kirkland Ethiopia Light Roast -- for the thermal level and the thermal stability reasons.

Conclusion: Making the Impossible Coffee Possible

The Kirkland Ethiopia Light Roast is famous among coffee lovers for being a "heartbreak bean"—it’s delicious when done right, but almost impossible to pull on a standard home espresso machine. Most machines simply aren't hot enough or adjustable enough to handle such a dense, specialty bean.

But today, the S01A-9BAR proved it is in a league of its own. Even when my grind wasn't perfect, the machine gave me the "manual overrides" I needed to save the shot:

• The "Heat Soak": I could push the temperature higher than a standard machine to unlock those hidden floral and citrus notes.
• The "Rescue Valve": By using the ball valve, I could slow down the water flow by hand, ensuring every drop captured the rich flavor I was looking for.
• The "Second Chance" Infusion: Halfway through, I could pause and add fresh hot water to keep the extraction deep and sweet.

The Result? A rich, aromatic latte that would have been a sour, wasted "sink shot" on almost any other machine.

The S01A-9BAR isn't just a coffee maker—it's a tool that ensures you never waste a rare bag of beans again. Whether you’re a beginner or a pro, this machine gives you the control to turn a "bad day" into your best cup of coffee yet.