Compression release valve

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Dec 19, 2011 | 06:27 PM

#11

1fathog

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Joined: Jan 2010

Posts: 307

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From: S. Florida

2010 96" does not have ACR releases. Only the 103"

Dec 19, 2011 | 07:27 PM

#12

KingCripps

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Joined: Aug 2009

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I have the hot start problem with a stage II 103 kit as well, 255 cams. Compression releases were never mentioned when the dealer did the work. Harley says they are not needed, BS.

If I can do the work myself, $150 for drilling, $140 for ACRs and a $40 harness, I don't know what the head gaskets sell for. So I am looking at about $330. I can get the heads CNC machined for $525, considering whether or not to do that while they are off. I'm concerned about fuel usage and whether performance will be degraded because I don't want to do cams again this winter

Dec 20, 2011 | 02:00 AM

#13

grbrown

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Joined: Jun 2007

Posts: 45,429

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From: Bedford UK

Quote:

Originally Posted by Skeeter229

Why do you think it already has a release valve? I'm not saying you are wrong just wondering why.

Not easy to answer, but one reason I can think of is to enable one starter motor to fit and start all stock engines. If the factory was to fit ever larger starters they will get bigger and more expensive, so it may be a case of balancing costs against each other.

On my 1990 bike I now have an S&S 107" which came with automatic releases. I have been running with the stock 1.2kW starter, but that has given up the ghost this summer, so I now have a 2.0kW one!

Dec 20, 2011 | 08:44 AM

#14

FBFletch

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Joined: Dec 2005

Posts: 1,078

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From: Hickory, NC

Quote:

Originally Posted by KingCripps

We've had this discussion on the forum before. Most Harley dealerships don't know crap about building a performance engine. For the most part, they're simply pulling parts off the shelf and throwing them together with little practical knowledge of how they'll actually perform together. And, while that's not always the case, it happens more often than not.

Having said that, there's plenty of real life examples out there that points to the fact with a Stage 2 kit for the 103s and the 255 cams, compression releases are needed. For a dealership to say that they aren't is either completely ignorant or completely irresponsible.

My opinion on MCRs (for about $50) as opposed to ACRs (for around $200) is that it depends on the consequences of forgetting to press the compression releases. A friend of mine used to be a service manager for a HD dealership. On two seperate occasions, the same customer brought his bike (11.0:1 CR) into the dealership because he had trashed the starter by forgetting ONE TIME to depress the compression releases. To me, that's an example where ACRs are justified. If there is little potential to damage the starter by forgetting to depress the compression releases on occasion, I'm all for MCRs.

I'm somewhat new to having CRs on my own bike. I have MCRs and thought it would be difficult to remember to depress them. However, I have yet to forget them even one time (knock on wood). Admittedly, it's easier to remember on a carbureted bike where you set the choke before a start anyway. However, it's now simply part of my pre-start routine.

Personally, given that you have a Stage 2 kit and 255 cams, if you're going to have the head off anyway, it makes sense IMHO to go ahead and have the heads machined for the CRs.

Dec 20, 2011 | 08:46 AM

#15

grbrown

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Joined: Jun 2007

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From: Bedford UK

I have ACRs on my S&S 107". Never once forgotten to use 'em, in over 3 years!

Dec 20, 2011 | 10:15 AM

#16

mllgator

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Joined: Jul 2010

Posts: 494

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From: Music City, USA

Quote:

Originally Posted by Skeeter229

Why do you think it already has a release valve? I'm not saying you are wrong just wondering why.

I believe, auto compression releases are standard on 2010 (and newer) touring bikes, becauseI went to a "horsepower seminar" at a local dealer and the discussion/presentation centered on (their selling) "Big Bore Kits". The kit included boring out my existing 96 to 103ci, new pistons, installation of a SE-255 cam, and re-map (a tuner was recommended, but was additional $).
When the question of compression releases was raised, the tech said that 2009 & up models come with auto compression releases.
That said, if you go to a true (the set-up above is not) high compression piston, hotter cam, etc., manual compression releases may be warranted.