Kibblewhite compression releases

Dan1950 said:
Why would you need a compression release?
Click to expand...

They are very useful with big piston engines. I have 2 stihl .090' chainsaw engines that I use to mill logs with, and they have a compression releases because no human could pull start those powerheads without one, It would be a nice feature for a kickstart commando. I've often thought a commando could benefit from a compression release, especially the automatic ones they make now that close automatically once the engine starts....
 
Try doing this. T.C. of Hogslayer fame RIP used to do this modification. I can't remember whether he wanted $500 a hole or $250 each. He did say he had a jig and it was important to get it placed right in the combustion chamber. Between the plug hole and head bolt. I don't know if his shop still exists? Sunset Motors. Google
 

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robs ss said:
What? & Why?
Click to expand...
They are made for chainsaws etc
But fitted to big twins
You push the button in ,kick the motor over without compression and only when the motor fires the valve automatically closes and you ride off into the sunset
That's the theory, I've never used one myself
 
The head on these valves falls off, especially on the cheap Chinese knock-offs. So if you want your combustion chamber not to be destroyed make sure the final hole is smaller than the head on the end of the compression release.
 
Everyone asking "why?"

Because it works great.
I can kick start anything, but, there are some who struggle.

Example: my 1975 DT400 has an automatic device that is actuated when the kicker is moved.
Works effing brilliant. You can start it with sneakers on.

The BEST example was the Yamaha Enticer 250 pull start snowmobile. The decompressor flip lever allowed my 8yo boy to pull start it on his own.
I'd be in the camp, cooking breakfast, watching him ride the daylights out of it on the lake.
Priceless.

My chainsaw has it.

Big modded Harleys need them.

The Sunset Motors mod is brilliant.

Dan, are you bringing that Hotrod to Woodstock? I want to see how it goes. 😎🏁
 
Last edited:
concours said:
Everyone asking "why?"

Because it works great.
I can kick start anything, but, there are some who struggle.

Example: my 1975 DT400 has an automatic device that is actuated when the kicker is moved.
Works effing brilliant. You can start it with sneakers on.

The BEST example was the Yamaha Enticer 250 pull start snowmobile. The decompressor flip lever allowed my 8yo boy to pull start it on his own.
I'd be in the camp, cooking breakfast, watching him ride the daylights out of it on the lake.
Priceless.

My chainsaw has it.

Big modded Harleys need them.

The Sunset Motors mod is brilliant.

Dan, are you bringing that Hotrod to Woodstock? I want to see how it goes. 😎🏁
Click to expand...
Big modded Harleys don't need them if they have the proper cam grind.

Yes my plan so far is to bring Trixie to Woodstock.
 
The release valves on the Stihl's are spring loaded and do not automatically close, so you have to hold the motor steady with one hand and with your thumb down on the release button. Then pull the start rope with all your might with the other hand and time the release of your thumb with the full extension of the pull. If you don't time it right, the kickback will rip the handle out of your hand like stealing candy from a baby... and it hurts a lot

Last year I had to get on a ferry, shut the engine off, then wait a bit and restart my bike to get off. I didn't flood the bowls on the restart because I thought it might still be hot enough to start without bleeding the carbs. The bike kicked back twice in a row, and got me in the upper calf both times. I had a hematoma the size of a baseball on my calf for about a month with blood showing up under the skin between my toes and the side of my foot from those 2 hits... You bet your ass I would have liked a compression release...

As Concours was saying there is also a bike that has a mechanism that holds the exhaust valve open slightly when you move the kick lever... that's genius stuff right there, and it does much of the same thing as a decompression valve. It solves a known occasional headache of big bore engines without electric start.

As Kommando said, If the decompression valve can break and fall into the bore, that's a good reason to NOT even consider a decompression valve installation... I like the exhaust valve mechanism idea more,... so give me a few years and I'll be posting my homemade valve decompression lever.... 🤣
 
o0norton0o said:
The release valves on the Stihl's are spring loaded and do not automatically close, so you have to hold the motor steady with one hand and with your thumb down on the release button. Then pull the start rope with all your might with the other hand and time the release of your thumb with the full extension of the pull. If you don't time it right, the kickback will rip the handle out of your hand like stealing candy from a baby... and it hurts a lot

Last year I had to get on a ferry, shut the engine off, then wait a bit and restart my bike to get off. I didn't flood the bowls on the restart because I thought it might still be hot enough to start without bleeding the carbs. The bike kicked back twice in a row, and got me in the upper calf both times. I had a hematoma the size of a baseball on my calf for about a month with blood showing up under the skin between my toes and the side of my foot from those 2 hits... You bet your ass I would have liked a compression release...

As Concours was saying there is also a bike that has a mechanism that holds the exhaust valve open slightly when you move the kick lever... that's genius stuff right there, and it does much of the same thing as a decompression valve. It solves a known occasional headache of big bore engines without electric start.

As Kommando said, If the decompression valve can break and fall into the bore, that's a good reason to NOT even consider a decompression valve installation... I like the exhaust valve mechanism idea more,... so give me a few years and I'll be posting my homemade valve decompression lever.... 🤣
Click to expand...
I believe the bigger panthers have a half compression lever on the side of the engine
 

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