What does a vacuum piston do in a CV carburetor?

The vacuum piston works with the carburetor's diaphragm. Engine vacuum pulls the piston up, which in turn lifts the needle and allows fuel to flow into the engine. This part is crucial for regulating fuel delivery based on engine load.

What Harley-Davidson models does this vacuum piston fit?

This piston is designed for 1988-later XL and 1990-later Big Twin Harley-Davidson models that use the CV carburetor. This includes many Electra Glide, Heritage Softail, Dyna, and Road King models from the 1990s and early 2000s.

Does this part come with any other carburetor components?

This product is for the vacuum piston only. If you are rebuilding your carburetor, you may need to purchase other seals, gaskets, or jets separately to complete the job.

Twin Power 88-Up XL 90-Up Big Twin Vacuum Piston For CV Carburetor Replaces H-D 27585-88

Specifications

Brand: TwinPower
Part #: 488783
UPC: 887337231518

Twin Power 88-Up XL 90-Up Big Twin Vacuum Piston For CV Carburetor Replaces H-D 27585-88

Name: Twin Power 88-Up XL 90-Up Big Twin Vacuum Piston For CV Carburetor Replaces H-D 27585-88
Brand: TwinPower
SKU: twinpower-twin-power-88-up-xl-90-up-big-twin-vacuum-piston-for-cv-carburetor-rep-t14-610532
Price: 56.31 USD
Availability: BackOrder

$56.31

On Backorder — Expected to ship by Apr 26, 2026

Order now to reserve yours — we'll ship as soon as stock arrives. Full refund if we're unable to fulfill.

Twin Power CV Carburetor Vacuum Piston for Harley-Davidson XL and Big Twin models. Replaces H-D 27585-88.

Key Features

Fits 1988-later XL and 1990-later Big Twin Harley-Davidson models with CV carburetors.
Direct O.E.M. replacement for Harley-Davidson part number 27585-88.
Restores proper function to the CV carburetor's vacuum-operated diaphragm.
Well-built to ensure smooth operation and reliable fuel delivery.

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Will this fit your vehicle?

Product Details

This is the Twin Power vacuum piston for your CV carburetor, designed to replace the worn-out or broken original part. If your Harley-Davidson's CV carb isn't responding like it used to, or if you're doing a full rebuild, this component is key to restoring proper function. It's a direct replacement for the Harley-Davidson part number 27585-88.

This vacuum piston is built to fit a wide range of Harley-Davidson models from the late 80s and 90s through the mid-2000s, including popular bikes like the Dyna Super Glide, Heritage Softail Classic, and Electra Glide Standard. Getting this part right ensures your carburetor's diaphragm operates smoothly, controlling fuel mixture based on engine vacuum. It's a well-built piece that gets the job done, bringing your bike's fuel delivery back to spec.