Automatic Compression Release

    Part Number 28861-07A





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    Automatic Compression Release (ACR) valves reduce the strain of starting your high performance motor by reducing cylinder compression - automatically! The engine is easier to turn over resulting in less wear on your starter and battery. After start, the ACR valves close to restore full compression.

    • ACR can be installed on stock or Screamin' Eagle® Performance cylinder heads for all '07-later Twin Cam equipped models
    • Install requires machining to be performed by a competent machinist using the Screamin' Eagle® Automatic Compression Release Fixture Kit P/N 94648-08 (sold separately)
    • Installation requires separate purchase of model specific ACR Wiring Harness


    • Warranty

      1 year limited warranty – Go to for full details
    • Sold in Unit

    • In The Box

      Valve only


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    Fits '07-'17 Twin Cam-equipped models. Can be used with Original Equipment or Screamin' Eagle® Cylinder Heads. Does not fit with Twin-Cooled engines.

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    More Info

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      • These Screamin' Eagle® products are 50-state street-legal for sale and use on all vehicles, including those that are pollution controlled. Complies with the requirements of 40 CFR Part 86, subparts E and F.


      Q & A

      Automatic Compression Release

      I am installing a SE 120R in a 2001 Harley Davidson FATBOY.The engine requires ACR to be install on this motor. It is a carbureted motor. Can the ACR be wired on this bike?
      Asked by: Terminator808

      Are ACRs standard equipment on stock 2014 Dyna FXDCs?

      My starter on the bike Struggles to get the engine cranking over. Once it starts cranking, no problem it spins up normally.
      Asked by: Wally384

      I've a 2008 Road King CVO with ACR's already installed, to replace the ACR's can I perform this procedure without removing the heads?

      The machining process on the heads should be complete if it already has ACR installed. Can I replace the ACR's without removing the heads? Do I require 1 ACR solenoid for each cylinder head, totalling 2? What is the torque specifications for the ACR's install? Thanks, for any input.
      Asked by: BozHog

      Automatic compression release

      I have a 2008 96ci with the 103 upgrade package including manual compression releases. Will the automatic releases work in the cylinder heads where the manuals have been installed? If not, what would I need to do to install the ACRs in my heads
      Asked by: Riderdave
      Hello Riderdave, The ACR's do not mount on the outside of the heads like most manual compression releases. They mount in the center of the heads. Thank You!
      Answered by: JD34
      Date published: 2017-03-26

      installing the ACR

      I have a 2009 road king, dose the cyl heads have to be removed to install the Automatic Compression release?
      Asked by: jjones211
      Hello Jjones211, Yes, the heads should be removed to install the ACR. Metal particles could fall into the engine and cause damage while it is being machined. Thank You!
      Answered by: JD34
      Date published: 2017-04-16
      • y_2018, m_2, d_26, h_20CST
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      • loc_en_US, sid_PA-18-2886107A, prod, sort_[SortEntry(order=SUBMISSION_TIME, direction=DESCENDING)]
      • clientName_harleydavidson

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