SE 254E cam and 103 bore
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Tourer
Joined: Mar 2011
Posts: 344
Likes: 4
From: Kailua, Hawaii
SE 254E cam and 103 bore
Today I ordered my 103 bore kit and 254E cams, I bought the jugs and pistons separate and got 10.5:1 compression pistons. I hope this is gonna be a good combo. Should I install compression releases too or is it not necessary? Heads are staying stock for now, might port them or change them out later on down the line. Anything else I should look into since im pulling the motor apart?
Jay
Jay
Cruiser
Joined: Aug 2010
Posts: 208
Likes: 1
From: Minnesota
compression releases
If your going to drag race it and be using a hand held crank starter, then no. If you are using it to drive on the public streets, put compression releases in to ease starting. Even with compression releases, you may run into it failing to start on really hot days. On H-D's street compression really shouldn't exceed 9.5:1 from my experience. Don't get me wrong, you'll enjoy the snappier response from your upgrade, just be prepared to baby it more and think more about your trips ahead due to it's fussier behavior. So put in the compression release and ride on! 
Road Master
Joined: Feb 2011
Posts: 992
Likes: 20
From: Arizona
I did the 103"with 10.5:1, 259E cams and no head work other than springs in my 2010 Fatboy Lo and love the results. Definitely put compression releases in as it's a must on hot days. I was told to just get in the habit of using them always as it saves on the starter. You will love the build.
Cruiser
Joined: Dec 2010
Posts: 161
Likes: 2
From: Louisville, KY
I have them with my build and use them always, it really is a big help, for the 100 bux or so I say ya.
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Ultimate HDF Member
Joined: Feb 2008
Posts: 7,217
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From: Southern Ohio
I did the 103"with 10.5:1, 259E cams and no head work other than springs in my 2010 Fatboy Lo and love the results. Definitely put compression releases in as it's a must on hot days. I was told to just get in the habit of using them always as it saves on the starter. You will love the build.
I'm looking at a 103" build, with some headwork, and my guy recommends the 259E cams.
Glad to hear good things about them.
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Stellar HDF Member
Joined: Feb 2010
Posts: 3,396
Likes: 266
From: Southern California
Use this website to see what you'll wind up with: http://www.bigboyzheadporting.com/TwinCamComp.htm
My engine when stock at 96" had a Static CR of 9.29:1 and Corrected CR at 8.77:1
As built in my signature; 103" with Andrews 26H Cams and a 0.030 Head Gasket it's a Static CR of 10.14:1 and Corrected CR of 9.53:1
I elected not to use Compression Releases. To say that it gets a bit warm here in Southern California, particularly out in the high desert, would be an understatement. I have been very conscious that I am skating on the thin edge of what might require the use of Compression Releases for these engines. That said, I have put a bit over 5,000 miles on this engine build. Since the build, I have had the engine try and kick back on the starter only twice. What will fry the electrical parts of the starter is if you don't immediately release the starter button when this happens. If you insist on forcing the issue you may also break the starter clutch (bendix). You need to make the call. In my case, I know myself well enough to know that I'll never remember to use manual Compression Releases when I should and I didn''t want to spring for the added cost of Automatic Compression Releases until I was sure I was going to have any sort of a persistent problem. As is, I'm OK with the decision I made, given how I ride. If and when the starter motor gives out the devil will have his due I suppose, but in the mean time it seems to be working OK for me.
My engine when stock at 96" had a Static CR of 9.29:1 and Corrected CR at 8.77:1
As built in my signature; 103" with Andrews 26H Cams and a 0.030 Head Gasket it's a Static CR of 10.14:1 and Corrected CR of 9.53:1
I elected not to use Compression Releases. To say that it gets a bit warm here in Southern California, particularly out in the high desert, would be an understatement. I have been very conscious that I am skating on the thin edge of what might require the use of Compression Releases for these engines. That said, I have put a bit over 5,000 miles on this engine build. Since the build, I have had the engine try and kick back on the starter only twice. What will fry the electrical parts of the starter is if you don't immediately release the starter button when this happens. If you insist on forcing the issue you may also break the starter clutch (bendix). You need to make the call. In my case, I know myself well enough to know that I'll never remember to use manual Compression Releases when I should and I didn''t want to spring for the added cost of Automatic Compression Releases until I was sure I was going to have any sort of a persistent problem. As is, I'm OK with the decision I made, given how I ride. If and when the starter motor gives out the devil will have his due I suppose, but in the mean time it seems to be working OK for me.
Intermediate
Joined: Jan 2009
Posts: 39
Likes: 0
From: Maryland
I have the same exact motor on my 08 Fatboy! You def want the compression releases! You are going to love it, the cams make pulling away from anyway in any gear a breeze. Just watch the front end...it will come up way easier now!
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