Wireing decompressors
Tourer
Joined: Sep 2012
Posts: 415
Likes: 1
From: Virginia Beach
I would think that pulling the heads, drilling and tapping them would be the long pole in that tent. Compared to that, I wouldn't think wiring would be that expensive.
Extreme HDF Member
Joined: Sep 2010
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From: Phoenix '53, '88, '09 Big Twins
Hmm,
looked at the 09 wiring diagram and there is no facility there, and no ACR facility at the ECM.
So this may require a change in ECM wpuld be required ( and would the thundermax be a better, less expensive way to go?)
but manual CR's would be fairly easy ( I see that a pair of JIMs are under $100)
Mike
looked at the 09 wiring diagram and there is no facility there, and no ACR facility at the ECM.
So this may require a change in ECM wpuld be required ( and would the thundermax be a better, less expensive way to go?)
but manual CR's would be fairly easy ( I see that a pair of JIMs are under $100)
Mike
Last edited by mkguitar; Apr 14, 2014 at 03:22 PM.
Ultimate HDF Member
Joined: Jan 2008
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From: SoCal
Here is the instructions that come with the harness 70623-08, that I think would be used to wire in the ACR's. I put them in my 08 FLHX when installing my MVA heads. http://www.harley-davidson.com/en_US...ts/-J04441.pdfThe ecm has to be enabled using the dt or a sepst, tts or pv.
Tourer
Joined: Sep 2009
Posts: 401
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From: Escondido, CA
I had this done a few years ago. Local shop wanted about a grand. I can't remember if that included the ACR's which cost about $100-150 as I recall.
Anyway, it was well worth it in my case. I had severe starter kick back thanks to the engine build from a 96 to a 103 by the former owner. He told me, ".... all Harleys kick back like that....". Idiot that I am and new to Harley I accepted that for a few days and then I came to my senses and had the compression releases installed, plus I had it built to a 107 since they had to go in there anyway. What a freaking relief to start the bike without people nearby saying, "Holy crap, that doesn't sound good!"
VR
Anyway, it was well worth it in my case. I had severe starter kick back thanks to the engine build from a 96 to a 103 by the former owner. He told me, ".... all Harleys kick back like that....". Idiot that I am and new to Harley I accepted that for a few days and then I came to my senses and had the compression releases installed, plus I had it built to a 107 since they had to go in there anyway. What a freaking relief to start the bike without people nearby saying, "Holy crap, that doesn't sound good!"
VR
Last edited by HOGNOT; Apr 14, 2014 at 04:46 PM.
Seasoned HDF Member
Joined: Jan 2011
Posts: 157,463
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From: Michigan 15 Minutes East Of Hell
Wire them through the "start" switch ... or you can buy the harness and hook it through the ECM ( a bit of a task ) and good eyes needed.
http://www.harley-davidson.com/en_US...ts/-J04441.pdf
http://www.harley-davidson.com/en_US...ts/-J04441.pdf
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Ultimate HDF Member
Joined: Jan 2008
Posts: 6,532
Likes: 132
From: SoCal
I had this done a few years ago. Local shop wanted about a grand. I can't remember if that included the ACR's which cost about $100-150 as I recall.
Anyway, it was well worth it in my case. I had severe starter kick back thanks to the engine build from a 96 to a 103 by the former owner. He told me, ".... all Harleys kick back like that....". Idiot that I am and new to Harley I accepted that for a few days and then I came to my senses and had the compression releases installed. What a freaking relief to start the bike without people nearby saying, "Holy crap, that doesn't sound good!"
VR
Anyway, it was well worth it in my case. I had severe starter kick back thanks to the engine build from a 96 to a 103 by the former owner. He told me, ".... all Harleys kick back like that....". Idiot that I am and new to Harley I accepted that for a few days and then I came to my senses and had the compression releases installed. What a freaking relief to start the bike without people nearby saying, "Holy crap, that doesn't sound good!"
VR
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Extreme HDF Member
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From: Phoenix '53, '88, '09 Big Twins
they allow a starting motor to spin a few times without compression to build up forward momentum, then the compression releases close, and the motor will then have fuel/air, spark, and compression and can start up.
the automatic CR ( ACR's) are used by H-D on the 103 motors.
and as discussed here, can be added to other models
the old Vincent Black Shadow had them controlled by a lever on the left bar
manual types are often just set into position by the rider and will close automatically
the twin cam motor has a light flywheel compared to earlier V twin motors, this allows the motor to build RPMS more quickly, but there are drawbacks, such as lower forward momentum, poorer low speed operation ( my '53 can ride at 600 rpms)
the twin cam is also typically higher compression than earlier motors
all this means that a motor trying to start can 'rebound" or reverse direction if the piston doesn;t have enough forward momentum to gets past Top Dead center ( TDC) on the compression stroke
mike
Last edited by mkguitar; Apr 14, 2014 at 05:33 PM.
The overlay harness isn't a big deal, but you have to reconfigure the fuse block, and open the ecm main plug. (at least that's what I had to do on my bike). Later 103 heads, and many SE heads are already machined to accept the acrs. I enabled my acrs via tts.