Add a decompression valve without modifying your engine

chainmaker

Member
Joined
Nov 9, 2009
Messages
472
Just food for thought, along with compression being released through that valve in the nice billet head you will also be releasing oil onto said head. Even still I am considering such a set up for my Briggs.
 


jefuchs

Member
Joined
Nov 8, 2012
Messages
92
Yes, my head is a mess, but the motor is easy to start. It's a trade-off, like so many things in life.
 

chainmaker

Member
Joined
Nov 9, 2009
Messages
472
How big is that vent hole on it , could you take a pic with a penny or dime next to it, maybe enlarge it a bit and thread a piece of tubing run it to a puke tank.
 

relaxxx

Member
Joined
May 2, 2008
Messages
97
Wow, that is insanely expensive for something you could build yourself from a cheap/broken spark plug and a few extra parts. A while back I had an idea to modify a spark plug by cutting some slits in the threads and attaching a little wrench to act as a leaver to open/close the plug. Never tried it though. I had a plug go loose before and black burned oil was bubbling out of the top, wouldn't that eventually clog up a valve.
 
M

Millsy

Guest
I invented this idea in my head earlier today, only to find that someone else has already made it. It allows you to use your spark plug opening for double duty, adding decompression capability.



Here's the source:
http://smccycles.com/catalog/product_info.php?language=en&products_id=305

It's very expensive. I added my decompression valve for about $15 by drilling and tapping my head cover. If you have one of those cool cnc head covers, it may not be an option.

To be honest, I don't know if this fits an HT engine, but I love the concept.
 

Frankenstein

Well-Known Member
Joined
Jun 24, 2016
Messages
5,078
My version would be a 6mm threaded hole, an Allen head bolt, and a small copper washer. Turn left to decompress.
 
S

Stihl044

Guest
I invented this idea in my head earlier today, only to find that someone else has already made it. It allows you to use your spark plug opening for double duty, adding decompression capability.



Here's the source:
http://smccycles.com/catalog/product_info.php?language=en&products_id=305

It's very expensive. I added my decompression valve for about $15 by drilling and tapping my head cover. If you have one of those cool cnc head covers, it may not be an option.

To be honest, I don't know if this fits an HT engine, but I love the concept.

Please let me know where I can buy one, the above link does not work...
 

MRSERIOUSMOJO

New Member
Joined
Sep 21, 2018
Messages
5
Ok...us old guys used to use these oil foul adapters in our worn out engines...Wouldn't let oil get to the plug as easy and foul it out...Been awhile since I've had one in my hand but I think you could make this work by drilling a hole and making some kind of release....Might go get one and see what I can come up with....Only around $4 ...a lot better than $100 if you can figure it out!!
 

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Barry The Bike

Guest
Wotcha. I like your Decomression Valve, would it be suitable for my 80cc 2 stoke chiness bike engine, if so where can I buy one?
Regards Barry.
 
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