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Polarstar Kythera (Semi-Auto) V2 - (M4_M16)
Polarstar Kythera (Semi-Auto) V2 - (M4_M16) 2
Polarstar Kythera (Semi-Auto) V2 - (M4_M16) 1
Polarstar Kythera (Semi-Auto) V2 - (M4_M16)Polarstar Kythera (Semi-Auto) V2 - (M4_M16) 2Polarstar Kythera (Semi-Auto) V2 - (M4_M16) 1

PolarStar Kythera SA V2 Mechanical HPA Engine for M4/M16 Airsoft Rifles

$287.99

Upgrade your M4/M16 airsoft rifle with the PolarStar Kythera SA V2 HPA Engine. Enjoy battery-free mechanical operation, a realistic adjustable trigger, consistent closed-bolt performance, excellent air efficiency, waterproof reliability, and a versatile 60–180 PSI tuning range.


Order today for same-day fulfillment • Estimated delivery Sep 7–8
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  • 14 DAY RETURNS

Benefits:

  • Battery-Free Mechanical HPA Performance Battery-Free Mechanical HPA Performance
  • Realistic Adjustable Trigger Response Realistic Adjustable Trigger Response
  • Consistent Closed-Bolt Accuracy Consistent Closed-Bolt Accuracy
  • Waterproof, Electronics-Free Reliability Waterproof, Electronics-Free Reliability
  • Efficient 60–180 PSI Tuning Range Efficient 60–180 PSI Tuning Range

Frequently Bought Together

Complete your setup with the most common add-ons.

PolarStar Fusion Engine Nozzle for M4/M16

$22.99

PolarStar Light Poppet Spring for FE/F2

$3.49

PolarStar Heavy Poppet Spring for FE/F2

$2.99

PolarStar Wire Harness Rev. 2

$10.99

Polarstar Regulator Gauge (0-220psi)

$8.99

PolarStar Kythera SA V2 HPA Engine for M4/M16

Transform your compatible M4 or M16 AEG into a dependable, battery-free HPA platform with the PolarStar Kythera SA V2 Engine. Its fully mechanical, waterproof design delivers efficient semi-automatic performance without an FCU, wiring harness, or electronic components.

Product Overview

The PolarStar Kythera V2 is a high-performance mechanical HPA engine engineered for Version 2 M4/M16 AEG gearboxes. Its closed-bolt operation completes the entire firing cycle with each trigger pull, providing consistent nozzle movement, reliable feeding, and quick follow-up shots.

A balanced spool valve and hardened alloy-steel sears create a crisp, realistic single-action trigger break and reset. Trigger weight, pull length, and overtravel are adjustable, while tunable nozzle dwell and return speed help optimize performance for different barrel and hop-up configurations.

Features & Benefits

  • Fully mechanical, battery-free HPA operation

  • Waterproof design with no FCU or electronics

  • Realistic adjustable trigger pull and reset

  • Closed-bolt system for consistent shot placement

  • Efficient valve design for excellent air economy

  • Adjustable nozzle dwell and return speed

  • Wide 60–180 PSI operating-pressure range

  • Semi-automatic operation ideal for CQB and DMR builds

Specifications

  • Engine Type: Mechanical HPA

  • Fire Mode: Semi-automatic only

  • Gearbox Type: Version 2

  • Nozzle: PolarStar #1 nozzle

  • Operating Pressure: 60–180 PSI

  • Manufacturer: PolarStar Airsoft

Compatibility

Designed for compatible M4 and M16 airsoft rifles using a standard Version 2 AEG gearbox. Fitment may vary between manufacturers and receiver designs.

What’s Included

Includes the configured Kythera SA V2 engine, correct trigger linkage, filter fitting, and model-specific conversion components. HPA tank, regulator, and air line are sold separately.

Installation

The Kythera installs as a single gearbox assembly and typically requires no gearbox modification. Proper alignment, trigger adjustment, and air-system setup are essential; professional installation is recommended for users without HPA technical experience.

Common Product Questions

Find quick answers about our airsoft products, shipping and policies.

Can LA Airsoft install this part for me?

Yes. We can build and upgrade Hi-Capas, AAP platforms, and rifles. Choose your base gun and parts, then add the appropriate tech service.

The current custom-build service states that builds are normally completed in approximately 3 to 5 days, with the team reviewing the selected parts for compatibility.

Do I need tools or gunsmithing?

That depends on the upgrade. Simple external parts may be straightforward, but internal upgrades can require disassembly, reassembly, adjustment and testing.

If you are not comfortable working inside your airsoft gun, our team offers professional tech and custom-build services.

How quickly will my order ship?

Orders without preorder items are typically packed the same day when placed before 4:30 p.m. Central Time. Please note that occasional delays can occur during especially busy periods or when staffing is limited.

How should I maintain this product?

Regular maintenance helps preserve performance and reliability. Keep the product clean, follow the manufacturer’s lubrication instructions, and properly manage batteries, gas systems, and internal components. More advanced repairs or internal servicing should be handled by an experienced airsoft technician.

Will this part fit my platform?

Compatibility is product-specific. Check the brand, model, size, and platform named in the product description, such as Tokyo Marui Hi-Capa 4.3 or 5.1, AAP-01, Umarex/VFC Glock, or a particular AEG gearbox type.

Similar-looking parts are not always interchangeable, so contact our team with your exact model if you are unsure.

Will this part increase my FPS?

Not every upgrade increases FPS. Some parts are designed primarily for reliability, cycling speed, weight reduction, or gas efficiency. When a product has a tested FPS claim, it should be stated in the listing.