ACR's
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Novice
Joined: Feb 2008
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From: Toronto, Ontario, Canada
ACR's
I own a 2008 Ultra with a Stage 2 kit installed. I've gone though a few starters and have been considering installing ACR's. I had a SE compensating gear installed as well but it hasn't totally resolved the issue. Has anyone had this installed done on a similar set-up and what do you think of the results?
Club Member
Joined: Sep 2010
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Are you looking at automatic compression release (ACR) or manual compression release (MCR)? ACR's will need a threaded port machined into the top of your heads under the rocker boxes along with a wiring harness instal and possible adjustments to your ECM depending on how you want them controlled. MCR's will require a threaded port machined in the heads next to the spark plug ports. MCR's are pushed in before starting and will close when the bike starts. I'm no expert on this but I was looking into it myself. I just did work to my wife's bike and I installed heads from a 2014 Street Glide that had the ports for ACR's in them so I could add automatic compression release.
Tourer
Joined: Sep 2010
Posts: 302
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From: Tulsa,OK
I have acrs on a 107 build. It definitely made a huge difference on starter wear and tear. The cost of the actual acr isnt as much of an issue as the more complicated machining. The pita portion of the install is wiring the harness. Well worth the trouble in my opinion. They're hidden and actuate everytime you start the bike.
Tourer
Joined: Jul 2014
Posts: 303
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From: Fort St.John, BC
You could always just purchase a good used set of 103" heads that already have them installed. I've seen many sets on eBay for a couple hundred bucks that came with the ACR's. Then you simply just need to wire them to your starter switch.
Seasoned HDF Member
Joined: Dec 2009
Posts: 9,163
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From: Doghouse... mostly
It all comes down to the ccp and compression ratio that you are running in your motor as to whether the releases would be worth the time and expense.
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Joined: Feb 2008
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From: Grays Creek, NC
My other engine is a S&S 106 that has a used set of 2012 heads with ACR's port and polished for my build. I didn't think wiring was difficult at all and my power vision turned them on.
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Seasoned HDF Member
Joined: Jan 2011
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From: Michigan 15 Minutes East Of Hell
Many/most Stage II kits come with the SE-255 cams which contribute to "hot start" problems ... Installing ACR's in your heads require specific machining tools ( which are quite expensive ) and a qualified machinist. Manual compression releases are a fairly straight forward installation and are quite simple to use. The other option is to swap heads with a set of later model ACR heads. There is a harness required to complete the installation and then the "flashing" of the ECM to turn them on. As mentioned earlier a Power Vision can do this. Also you can wire the ACR's through the "start circuit" and avoid/eliminate the optional harness.
http://www.harley-davidson.com/app-c...ts/-J04210.PDF
http://www.harley-davidson.com/app-c...ts/-J04210.PDF
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