Opinions needed regarding compression release
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Joined: Jan 2009
Posts: 70
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From: Owasso, Oklahoma
Opinions needed regarding compression release
My brother in law had an 09 SG with dealer installed 103 flat tops, SE255 cams, stage 1 map. It had over 215' cranking pressure, wouldn't start well & extreme detonation.Finally after many attempts they took it back & gave him an '10 SG 96". He is wanting to do another 103 with SE254e cams. I also am going to do my 10 SG 103 build but I want more cam than that. Should compression releases be considered on any 103 build with flat top pistons? Seems like since the heads will be off anyway, it moght be best to be safe than sorry.
Elite HDF Member
Joined: Jan 2008
Posts: 4,351
Likes: 461
From: Illinois
You are correct. When the heads are off anyway, you should install cr's. However, I don't believe the extra cubic inches are as much of a reason to require cr's as the cam choice. While I am a fan of the 255 cams, they do create starting issues with their high lift. More so than the extra cubes. JMHO
Dennis
Dennis
Retired Admin
Joined: Jul 2006
Posts: 21,865
Likes: 9,046
From: Wisconsin
I have a 103/255 build and when it's hot, I need the CRs. It's easy enough to put them in when you do the build, hard to do after.
P.S. I love the build. I was not looking for bigger top end but more bottom and middle power and this build does it well.
P.S. I love the build. I was not looking for bigger top end but more bottom and middle power and this build does it well.
Grand HDF Member
Joined: Mar 2010
Posts: 3,753
Likes: 3,170
From: Central Indiana
I did the stage 1 big bore to 103" when the bike was new....I did not do CR's and have never had a problem, but I wish I would have. If nothing else I think it would save wear and tear on the starter.
Seasoned HDF Member
Joined: Mar 2008
Posts: 9,377
Likes: 1,774
From: Central Texas
I have a set of cvo 103 scrept heads with 103+ pistons making
10.5:1 compression with no CR but I have the HD high preformance
starter even though tthe stock starter was working just fine
10.5:1 compression with no CR but I have the HD high preformance
starter even though tthe stock starter was working just fine
Ultimate HDF Member
Joined: Jan 2008
Posts: 6,532
Likes: 132
From: SoCal
If I had to do it again, I would do it the same way, SE Auto Compression Releases. They work without touching them and they don't hang open. Only small issue is having the head drilled for the acr's as they require the jig that SE sells to do the job and I don't know how many dealers have it. My heads were already set up so all I had to do was remove the plugs and install the acr's wire them up using a SE pigtail and enable them thru my SE tuner. They vent the cylinder pressure into the exhaust port. I was running without any comp releases and from time to time I would get the sneeze bang or the slow grind, happens no more and still using the stock compensator too, 103" 10.5-1 pistons, 195ccp.
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Grand HDF Member
Joined: Sep 2009
Posts: 3,806
Likes: 281
From: Green Country Oklahoma
Put CR in when get her modify and save money , I didn't do it and it was fine with heavy duty starter and SE compensator but after 20k miles all the wear and tear it started to give starting troubles again. Now it's going to cost nearly $ 700.00 to install CR not very smart.
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