compression release lifespan

Discussion in 'Engine, Fuel and Exhaust' started by AliveAgain, May 24, 2011.

  1. AliveAgain

    AliveAgain Member

    I did a search and it came up blank. It seems I've been seeing comp release options on heads in a few posts. I wondered what happens when they go bad or when they need to be replaced. If used on a daily rider, would they need to be replaced every year,5, never? On my other bike, I just used a 24 volt starting system and that was 14.8/1 comp on the street. At what horsepower would the release start to become necessary?
  2. glider

    glider Veteran Member

    Rule of thumb is a 10-1 CR would dictate the need for compression releases. As far as how long they last, that would depend on how often they are used but I wouldn't worry until they expire. The 24V may make a difference in longevity too.
  3. ckhismine

    ckhismine Active Member

    I can not recall ever seeing one fail and I know a lot of people that run them.

    BUBBIE Well-Known Member

    The way I look at it:

    I think I would Never worry about the LIFE of the RV unit.. LONG LIVED from what I've been told and seen..

    If you modify a stock motor and check the CCP and it is OVER 190 lbs, hard starting MAY be an ISSUE..

    A lot of 96" bikes going to SE 255 cams THEN GO 103", USUALLY need to have manual Compression reliefs installed(OR Should) when the are torn down to go 103" ..

    The usual complaint (higher compression) is hard starting/kick-backs ,,, when Hot starts after a shut down can show a problem.. Hard on the starter and damage to the starter clutch.

    Usually these Modified bikes will have 200/205 lbs of static compression and NOT all Will BUT MANY Will do the Kick backs. (180 lbs compression is good place to stay)

    Tuning and a Fueler have a lot to do with this Hard/Easy Starting also.. Two bikes built the same can act totally different from each other..???

    I have SE 255's and full stage one now and use a TFI for my fueler in my 09 96" FLHR,,, I plan to go 103 when my 96" build is OLD and I will install MPRV at that time... YES ,,,,Needing and installing the relief valves at that time.

  5. flh canuck

    flh canuck Active Member

    Never heard of compression release failure.

    Perhaps it could be an issue with the automatic (electric) releases but I have manual releases installed in my 103" engine.

    The manual releases are pretty basic so not much to go wrong with them. I have heard people complain of them closing too soon but no issues with mine and if there ever was a problem, they are easy to service.

    Would for sure recommend them if you are doing any mods that increase your compression ratio or ccp over stock.

    Takes a lot of the strain off the starter, primary and compensator etc. Even stock, my engine used to kick back once in a while and it sounded nasty.

    No starting problems at all since new build and installation of compression releases.