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[ridefar]

Looking for a technical reason why the 2012 103's are coming with automatic compression releases from the factory...thanks.

[cvobiker]

 Their purpose is to reduce cranking pressure so the starter can turn the engine with enough authority to get it going.   

[ridefar]

Thanks, but given that fact, why have they not been needed on previous motors and now required on the 2012? Or have they been on previous motors and I have been out of the loop?

[cvobiker]

Thanks, but given that fact, why have they not been needed on previous motors and now required on the 2012? Or have they been on previous motors and I have been out of the loop?

I would guess the 2012 103" has a cam/head/piston change from previous years changing cranking pressure so Harley added the compression releases.  

[HD Street Performance]

why have they not been needed on previous motors and now required on the 2012

They have been used in the CVO 110 from the inception and this was first a dealer campaign in 2008 on the 103 police Fls
You take a 96 and add cubic inches and change nothing else and cylinder pressures rise to the point issues arrise and the motorcycles were not making it through the warrenty period without collateral damage. The MOCO offered a new set of heads as the fix, software upload, and the harness for the ACRs. Also the 103 heads have a small cove cut in them to add a small amount of volume in the ACR area of the chamber. All in the interest of saving parts and reducing the chance of detonation (which also saves parts )

[tennisman]

My 110 had a faulty rear compression release that ended up tearing up the starter (IMO)....anyway, all fixed including new starter, clutch basket, and upgraded to the SE compensator (which is now on all new big twins, I believe).

[jabarr]

The 2011 103's in the Limited models all have had compression releases.  It's not new for 2012's.

[SteveFLHTK]

Thanks, but given that fact, why have they not been needed on previous motors and now required on the 2012? Or have they been on previous motors and I have been out of the loop?

The compression releases were actually started on the 2010 Limited, which was the first general production (read non-cvo or police) to come with a 103.

[HD Street Performance]

A 103 Police is identical to the 103 LTD

[ridefar]

Realizing its not apples to apples, why no compression releases on the SE103 from 2003 on? Wasn't that an 88 punched out to 103? Thanks Dewey you are always very informative.

[remington007]

SE 103's came with a intake lobe that closed at 53*. Open chamber in the heads, flat top pistons.......Not alot of compession with that combo!

[grc]

The static compression ratio on the old CVO103 was 8.9:1, versus 9.6:1 on the current TC103.  Add in the effect of the cam timing, and the current engines have a significantly higher cranking compression pressure.  Thus the need for the compression releases.


Jerry

[Limited Lou]

The compression releases were actually started on the 2010 Limited, which was the first general production (read non-cvo or police) to come with a 103.

 

[ridefar]

The static compression ratio on the old CVO103 was 8.9:1, versus 9.6:1 on the current TC103.  Add in the effect of the cam timing, and the current engines have a significantly higher cranking compression pressure.  Thus the need for the compression releases.


Jerry

Perfectly put so that it makes sense to me. Thanks man!

[plow7man]

I just upgraded my 2009 Ultra from 96 to 103. If you read the installation instructions carefully they tell to do the compression release as part of the install. The dealer was surprised when I asked why they didn't do it and the response was they never did and have not experienced any problems.