a working compresion release is here

[jfabmotorsports.com]

Forgot to mention...I might kick it in bare feet on you tube in a bit....maybe. 

[Danger4u2]

Your brave, wrap the foot peg with duct tape.

[kaw rider]

Jerry
That valve looks more heavy duty compare to the other one. I think this one will work great for guys that run nasty compression.

[jfabmotorsports.com]

The compression release lever that came with the generic valve kit was a small lever like the one that was used on the YZ426. I just installed a Moose lever set that had a Hot Start lever incorporated into it. It works and feels ok but I think the ASV style lever might be a little better. The little lever that came with the valve worked great but was not too sanitary.
JFAB

[Larry Wiechman]

Some blurry photos of my version of the big 14mm compression release installation. This was to prove out an installation on a CR500 that had really tight space limitations.
 

 

 
Long ago, these cable operated valves were used on 2-stroke flattrackers as an engine brake. Run up to the corner, pull the lever and flick'er in. Made for nice, easy slides and a cool farting noise as the valve bled off cylinder pressure. The down side in this application  was that the motor was sucking in dirt on the intake stroke. Then someone produced a valve that had small metal reed valves covering the discharge ports. Genius! No more Filtron foam wrapped around the compression release and it even functioned better, because now there was also resistance as the piston moved down. I've searched for a supply of the one-way valves, but I think they died with the 70's.
Simple solution, don't ride around at the back of the pack doing brake slides no matter how much fun it is!
 
Larry 

[jfabmotorsports.com]

     I toyed with the idea of welding a boss onto the head just as we have done with the 10mm x 1mm valves, only toward the rear of the head. I chose the stud mounted version because of less modification to the head. Also, if you decide that you do not like, no longer need it or want to sell the bike with out it, just remove the valve and put a nut back on the stud.
    I already have plans to minichureize the valve that I use in an effort to maximize mounting locations...and to cut out the middle man.

JFAB
 

[BullKaw]

Long ago, these cable operated valves were used on 2-stroke flattrackers as an engine brake. Run up to the corner, pull the lever and flick'er in. Made for nice, easy slides and a cool farting noise as the valve bled off cylinder pressure. 
Larry 

I don't want to hijack this topic but this is the second or therd time that I have read this. I do not understand how releasing the pressure from the cylinder will slow the engine. Someone has compared it to a Jake Break. A Jake Break releases the preasure just befor TDC after the resistance of compressing the intake stroke has taken place. With the pressure dumped at TDC there is no pressure to rebound the piston and the engine slows.
    I know it is done and it must work but I would like to know how.

[Friar-Tuck]

 BKaw,
 The application here is primarily to make the bike easier to start.
   As I see it, You are correct in that this is not an "Engine Brake", but merely an additional   application.
  The force of the piston pushing all that air out of the small passage in the valve will create some resistance.   
         If I'm not mistaken Jake Brakes "are designed" to use engine compression to aid in vehicle braking, not aid in starting.
  Hope I didn't just make this any more confusing...
 Tuck\o/

[Larry Wiechman]

    Also, if you decide that you do not like, no longer need it or want to sell the bike with out it, just remove the valve and put a nut back on the stud.
   
JFAB
 

 Do you really believe someone would not like, need or want a decompression device after having used one. Can you think of a better resale feature?
 I think the future is something like this concept patented by a Husky engineer.http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=6,253,723.PN.&OS=PN/6,253,723&RS=PN/6,253,723
 Small, automatic and simple.
 
Larry

[jfabmotorsports.com]

    Also, if you decide that you do not like, no longer need it or want to sell the bike with out it, just remove the valve and put a nut back on the stud.
   
JFAB
 

 Do you really believe someone would not like, need or want a decompression device after having used one. Can you think of a better resale feature?
   
 
Larry

Larry you are right. I had not looked at it in that way. I can't imagine not having decompression valves now that I have them.

JFAB

[Motorrad]

Digging the idea...  As im one of the many that can not run the chain saw setup (tank interferance). 

Few quick thoughts/questions..


Volumetrically how much extra area are we adding to the combustion chamber (how much space is in all of these adaptors, area around the stud, etc)  If you add it all up, are we getting into some serious numbers?

Hot exaust gas:  Over time, do you think there will be an issue with hot exaust gasses erroding anything?  studs, gasket serfaces around the stud.. Its amazing what things like this will do on car motors.. Will ditch things right up.

Sealing..  Just off looks, is thre now 3 serfaces you are sealing with that setup (spacer to head, adaptor to spacer, Compression release to adaptor)...  Things like that scare me a bit, being a desert racer, DNF due to  a stupid crush washer backing off etc sucks...

In another thread you said "There is a hole drilled into the chamber at an angle. The adapter is designed to capture the hole in a counter bore. " are you capturing it like say a banjo bolt?  or are you filling the entire area around the stud with combustion to then travel into the adaptor?

Anyone worked out a hotstart activated one yet? 

 
 Do you mean cable/lever operated?
 
Larry

   I have been working out the details of this idea for some time. I just finished it up this morning and if the rain here ever stops I will take the K5 out and thrash it a bit.
     I think it was Dutch-K5 Fan that said he was interested in using this type of valve. The valve can be bought all over the internet and with very little head work and the little adapter that I am going to offer it can be installed on just about any head on any bike.

JFAB     

[jfabmotorsports.com]

Motorrad,
    There are only 2 sealing surfaces, valve to adapter and adapter to head. The shinny piece is a machine mark from the lathe work on the adapter. The valve has a spark plug washer between it and the adapter. My proto type uses no washer between the head and adapter. A copper washer could be used.
    I did the some math to get a rough idea of the volume created by holes and it is less that 1cc. I will do an actual cc test latter.
    The exhaust gas does share the space with the head stud and I am sure over time there will be some oil build up in that area. As far as maintenance goes, I am skeptical that it will be more than is required to keep the KIPS working. The gasses moving past the decompression valve are not hot unless you hold the valve open for a prolong period of time.
    I have a little over 20 hours of testing on mine between me and my 13 year old nephews riding the k5.
View the video; I think the plusses outweigh any maintenance issues. Even if you had to clean the carbon from it ever so often.

In the video I point out the Hot Start lever. The bike was warm but not hot. That was the first and only take with the camera. First kick!


 http://www.youtube.com/watch?v=vXDVzyiV5oA

[Friar-Tuck]

AARGgghh... You're KIllin' me!   
          Dang JFab That's Great!!
As an aside, I don't personally know anyone who has had problems with their comp release on their chainsaws.
  I have an OLD Craftsman (made by Echo) in the 80's and that old girl has had no prob.
     Tuck\o/
 

[Motorrad]

Thanks jfab that answered a few questions I thought up really quick.  And I'm sure others had as well.

[Motorrad]

How do these comp releases work jfab?

Are they lome the chain saw ones that auto kick out when the bike fires?
Or do you have to hold the leaver down to keep it engaged?'

Hard to tell from the video if you continue to hold it down with your other thumb or not...

Reason I ask. is Im looking at these as a option to the "clutch side" hot start leaver.... But if you need to continue to hold it... it would be nice to be able to use the trottle..
http://www.asvinventions.com/RotatorClamp/RCU05.php