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Compression Release failure

Discussion in 'Motor' started by BroadBand, Jun 25, 2010.

  1. BroadBand

    BroadBand Since late 60's

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    Over the weekend, during a 250 mile charity poker run, I had a compression release destroy itself. It's the first real thing that has gone wrong on my Big Dog and it did not leave me stranded. I have 13,500 miles on it when I was putting along at 75mph and heard a loud pop. From that point on, I could hear a new & different sound. Did not really notice a loss of power or anything.

    At the next stop, I looked down to see the rear jug CR laying in the hole with the silicone boot kitty wampas. Everything was out of whack big time.

    Called my mechanic and he said it would probably not hurt anything to finish the ride and since I was 150 miles from home, that was a relief.

    The bike started OK everytime I shut it down. You could definetly hear the "che - che" sound of escaping compression out the small hole in the CR.

    Upon tear down, some of the CR was no where to be found. It either melted of broke off between here and there...

    It takes a special tool to remove/install the CR's. I replaced both with brand new CR's at a cost of $365 approx. I needed the 2 CR's and 2 gaskets for the rockers. It's now running strong like always.

    What follows are pictures of the old parts so you can get an idea of what the CR's look like incase you never have had all the fun this trip turned out to be.

    [​IMG]

    [​IMG]

    [​IMG]

    :flag:
     
    Big D Florida likes this.
  2. TCALZ06

    TCALZ06 Well-Known Member

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    Nice write up.

    Where did you buy the tool to remove them and how much did it cost?
     
  3. Eric

    Eric Banned

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    mine did the same thing with less than 3K on it.. rear cyl... it was under warrenty though...
     
  4. BroadBand

    BroadBand Since late 60's

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    Compression release tool

    The S&S tool is around $80.00 and is pictured HERE

    :flag:
     
  5. alphadog

    alphadog Active Member

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    Thanks for the info. Good to know. I would be curious to see how many others fail and at what mileage so we can replace em before they blow.
     
  6. Big Bruno

    Big Bruno New Member

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    What can I use to loosen a sticky CR? When I start, I have to crack the throttle. Front cylinder.
     
  7. Eric

    Eric Banned

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    I now have had to replace the frt cyl.to.. about 300 miles after the rear (rear relpaces right before warrenty went out) I bought the S&S comp.release tool & I got 2 comp releases ,replaced the frt & got a spare now.. now that I got 2 bdm with em I figured I had better invest in em & keep @ least 1 on hand.. not a difficult job .. the dam rubber cap is more difficult than the comp release..
     
  8. Nomad2day

    Nomad2day Longhair Redneck Geek

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    You can manually press it down before you start it.
    Carbon builds up on them as well and makes them stick as well. Just pull the rubber boot off and use some good penetrating oil on it and press on it until it loosens and springs up on it's own. I use Kroil penetrating oil myself.
    Been there and done this already. I also have the S&S tool as well.
    Neil
     
    Big D Florida likes this.
  9. BigDogBro1

    BigDogBro1 Made in the USA

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    I want to pull the compression release valves out and check for maintenance. Can I use a deep well 12pt socket to remove them?

    WHAT SIZE SOCKET?......12point, 1", 3/8" drive or what? 2-3/4" clear deep bore I've read on other another post.

    If a deep well socket will work I'll cut a hole in the side of it to allow the CR cable to exit out. Or cut out an extension corner.

    Do you need to pull the rocker covers off to get access to the CR for removal?

    Thanks
     
    #9 BigDogBro1, Dec 17, 2010
    Last edited: Dec 17, 2010
  10. john sachs

    john sachs Active Member

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    :up:
    NO,NO, NO.............
    Pull rockerbox top,and sometimes you need to remove the rocker arm saddle.
    Use only the S&S tool.The threads are VERY fragile. :bang:
    Do the job the right way. :up:
    John
     
  11. billyberoux

    billyberoux Member

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    Mine were always failing on my 04 big dog chopper so I pulled them out and plugged them up wth bolts and I've never had a problem starting the bike. The tool costs $60 but most shops will loan it to you so long as you put a deposit down.
     
  12. BigDogBro1

    BigDogBro1 Made in the USA

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    .
     
  13. BroadBand

    BroadBand Since late 60's

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    Hard to argue with that!!

    :flag:
     
  14. uberhawg

    uberhawg New Member

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    Excellent writeup. S&S doesn't let them show the price online but Retrocycle has that tool for $80.99 if you want one.
     
  15. Tom Chop

    Tom Chop Active Member

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    Thanks To Neil In Tennessee

    Nomad2day I appreciate the info on how to clean and lube the compression releases on our beloved "Dogs". I further agree that Krull Oil and lube would be best candidate for breaking down the carbon and lubing the "CR`s". Thank You Nomad2day and all contributers for the great tips. As usual here on the forum you all rock. :flag: :cheers: :2thumbs: :roll:

    Thank You All

    Be Kind

    Take Care

    Tom Chop
     
  16. TCALZ06

    TCALZ06 Well-Known Member

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    Looks like I have a rear compression release not working.

    Where are you guys buying these at? I see the kits but I only need one.

    thanks
     
  17. HotWheelz

    HotWheelz Member

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    What about just installing a set of manual Compression releases. My buddy had to install them on his 10.5/1 96 cu Harley.Why do it electronically?
     
  18. V

    V Guru

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    Just replace my rear one on friday. Got it from Lena At Strokers
     
  19. V

    V Guru

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    S&S has a manual set that has a cable that goes to both of them. I don't really like the looks of that set up. There are a couple of others out there wtih the 14mm thread that look like they would fit and you just push down on the top of them. If they would work that would be my choice.
    Then theres also having the head machined and thread for the 10mm ones.

    Anybody runnin the manual releases?
     
  20. awg

    awg Well-Known Member

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    Well it seems like a big expense when they fail. What harm to just plug them up and get rid of them?
     

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