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CVO Technical => Twin Cam => Topic started by: johnsachs on September 19, 2018, 06:36:49 PM

Title: Compression Releases
Post by: johnsachs on September 19, 2018, 06:36:49 PM
I'm seeing more plugged up compression release passages (release to exhaust port exit) on an above average # of heads coming in here with MoCo releases.  >:( It seems to favor the rear head. Several were so bad, I had to make/use a .110" diameter rod with a point to get through, and remove the blockage, which took Brakekleen, and a hammer. No way the release could have bled off pressure.
* Always check the passages.*
John
Title: Re: Compression Releases
Post by: MCE on September 19, 2018, 10:37:14 PM
Get a bigger hammer John!
Title: Re: Compression Releases
Post by: HD Street Performance on September 20, 2018, 08:58:57 AM
Same here.
I drill them between the pushrod tubes when retrofitting.
Title: Re: Compression Releases
Post by: MCE on September 20, 2018, 12:27:51 PM
Same here.
I drill them between the pushrod tubes when retrofitting.

You're venting them out the side then? That's an interesting way to do it, (hadn't thought of that).
Title: Re: Compression Releases
Post by: Phreakyz on September 20, 2018, 03:20:42 PM
You're venting them out the side then? That's an interesting way to do it, (hadn't thought of that).

You guys might as well be speaking Chinese to me!   How about some pics?
Title: Re: Compression Releases
Post by: MCE on September 20, 2018, 04:32:33 PM
You guys might as well be speaking Chinese to me!   How about some pics?

The factory ones vent out through a hole in the Ex port. I think Don is suggesting to drill the hole
out the side of the head. (that's my take, but I'm just a Texas redneck) 
Title: Re: Compression Releases
Post by: TorqueInc on September 20, 2018, 05:10:18 PM
The commercial spray stuff they use to remove carbon from pizza/baking pans turns the stuff in the carboned up hole into black goo that can be removed with a air hose
Title: Re: Compression Releases
Post by: longlast on September 20, 2018, 05:45:35 PM
You guys might as well be speaking Chinese to me!   How about some pics?

There are manual and there are auto types, they are screwed  into the heads. The auto ones open when you turn the ignition switch on so when you hit the starter they reduce the amount of cylinder compression too make it easier on the starter to crank the motor once it starts they close and there is full compression again.

Title: Re: Compression Releases
Post by: johnsachs on September 20, 2018, 06:40:07 PM
Get a bigger hammer John!
The way I use a hammer, I would wind up with a bigger exhaust port.  ::)
John
Title: Re: Compression Releases
Post by: johnsachs on September 20, 2018, 06:46:02 PM
Same here.
I drill them between the pushrod tubes when retrofitting.
I did that once after getting an OK from the customer. After all said and done, he was pissed because it blew s**t on his leg, got engine parts dirty, and made too much noise.  :nixweiss:
John
Title: Re: Compression Releases
Post by: OBB on September 20, 2018, 07:13:43 PM
The commercial spray stuff they use to remove carbon from pizza/baking pans turns the stuff in the carboned up hole into black goo that can be removed with a air hose
Won't ever be eating pizza at your place  :'(

 :huepfenjump3:
Title: Re: Compression Releases
Post by: prodrag1320 on September 21, 2018, 07:35:35 AM
have to keep my eyes open for this,i just plug them right off the bat when on the SERDI for seat work or on the flow bench,cant say I ever really checked to see if their clogged
Title: Re: Compression Releases
Post by: MCE on September 21, 2018, 01:32:53 PM
have to keep my eyes open for this,i just plug them right off the bat when on the SERDI for seat work or on the flow bench,cant say I ever really checked to see if their clogged


I run a short piece of TIG wire through the hole, haven't run across a blockage yet, but I'm definitely going to be
keeping a closer eye on it. (Thanks for bringing it up John)
Title: Re: Compression Releases
Post by: FlaHeatWave on September 22, 2018, 12:00:32 PM
Are you guys noticing any pattern(s)?? Mileage? Years? Models? Fuel? etc,,,
Title: Re: Compression Releases
Post by: HD Street Performance on September 22, 2018, 05:29:21 PM
No, but if the exhaust port shows signs of oil from down the guide or from combustion the port can get plugged. The other issue with the acts is they are not tight
Title: Re: Compression Releases
Post by: TorqueInc on September 23, 2018, 01:15:39 PM
Won't ever be eating pizza at your place  :'(

 :huepfenjump3:

I make a mean thin crust in my defense
Title: Re: Compression Releases
Post by: Twolanerider on September 23, 2018, 08:17:35 PM
No, but if the exhaust port shows signs of oil from down the guide or from combustion the port can get plugged. The other issue with the acts is they are not tight

What prevalence?  Of those you're disassembling or checking best guess as to a percentage that didn't maintain torque?
Title: Re: Compression Releases
Post by: MCE on September 24, 2018, 12:45:40 AM
I make a mean thin crust in my defense

I like making pizza too. I have a 3/4" thick ceramic baking stone in the bottom oven. Heat that
bitch to 550*. Hobart dough mixer too.  ;D
Title: Re: Compression Releases
Post by: Bagger on December 25, 2020, 06:02:21 PM
There are manual and there are auto types, they are screwed  into the heads. The auto ones open when you turn the ignition switch on so when you hit the starter they reduce the amount of cylinder compression too make it easier on the starter to crank the motor once it starts they close and there is full compression again.

I have manual compression releases in my 2002.  It'd be nice if there was an auto CR that'd screw into where the manual releases are for those of us still running older bikes.. 
Title: Re: Compression Releases
Post by: HD Street Performance on December 26, 2020, 09:23:42 AM
It wouldn't be hard to make adapter buckets but the whole mess would not be very attractive.