'76 WR360 compression release head?

[sweenster]

Old man posting disclaimer...Bad knees and wanting to preserve what I have left to RIDE while I still can! So anyway...
Does anyone know if a compression release head or system exist for a 1976 WR360 and if it does, where can I find it? Has anyone had any experience with one and "does it work"? So far no luck...
Brrraaapppp!

 

[fran...k.]

If you try out the search function in enouigh different ways you shouldn't come up empty. I never did it but have read about it here. Not sure if it was in someone's 430 restoration project only or other threads as well. None specific to the 360 that I recall. I think it is pretty standard for large chain saws to have compression releases. I understand years ago there were compression releases which could be used as brakes with cables to the handlebar but that was stopped supposedly due to dirt getting in.

It doesn't have to be in the head. some fin can be machined off half way between the reed block and the top of the cylinder and the device installed there. I have 3 420 cylinders and one of them has a hole going from half way between the exhaust port top and the cylinder top and connecting an inch and a half or so down the exhaust passage. I have seen similar hardly bigger than an eithth inch passage in Yamaha rd400 twin bike cylinders as well. It might have been quite common in a certain time window.

fran

 

[stormer254]

Lots of old british smokers have them, better than a kill button, it will not short out when you don not want it to and makes a very effective back break in slipperey conditions

 

[sweenster]

After much research and deliberation, this is the unit i'm going with.
http://www.outdoorking.com/index.php?main_page=product_info&cPath=193_514_302&products_id=1040
It's a victa lawn products part, tried and true on dirtbikes new and old alike. It even has matching threads to allow it to screw directly into the extra sparkplug hole so no need for massive alterations. The only milling will be drilling a hole directly into the carb on the reed cage side of the intake AFTER the venturis and BEFORE the reed cage, installing a vaccum fitting, then connecting the two via vaccum hose. I was told to make sure to "point" the carb fitting and head decompressor fitting TOWARDS each other. (OK... if you say so...) disclaimer: I am AWARE of a reduction in squish area. I will jet accordingly.

 

[dukkman]

All the ones I have fitted I have put on the right hand side where you can reach them.
These ones work real good and they come in pairs.
You just push them down and forget. They absorb any kickback protecting both your foot and sidecase.
http://vulcanworks.net/store_4/home.php?cat=1
The 10mm ones work great on my 400 and friends 430.

430

400 w/bottle

Even put one on my PE but it's a waste.

 

[sweenster]

All the ones I have fitted I have put on the right hand side where you can reach them.
These ones work real good and they come in pairs.
You just push them down and forget. They absorb any kickback protecting both your foot and sidecase.
http://vulcanworks.net/store_4/home.php?cat=1
The 10mm ones work great on my 400 and friends 430.

430

400 w/bottle

Even put one on my PE but it's a waste.

I'll give these a try if the auto/vaccum models don't work. thanks!

 

[NZHusky]

check out this thread, Is a Victa 2 stroke lawnmower part, 20- 30 bucks never have to touch it and you just kick the ole Husky into life easy!!

http://www.cafehusky.com/threads/au...-2-stroke-husky-easy.15000/page-2#post-134651

 

[dukkman]

I worked for Victa for 5 years as a serviceman and have seen the deco valves drop the little circlip off the end of the valve and have seen the end fall off where the circlip fits.
Needless to say the valve ends up in the engine.

 

[stormer254]

Go for a cable operated one as fitted to British and Spanish trials bikes , never heard of one of them going the wrong way

 

[fran...k.]

All the ones I have fitted I have put on the right hand side where you can reach them.
These ones work real good and they come in pairs.
You just push them down and forget. They absorb any kickback protecting both your foot and sidecase.
http://vulcanworks.net/store_4/home.php?cat=1

Could you clarify what one gets when ordering the item you linked to. I see that you get a pair but the picture shows three with the center one different. The edege ones perhaps seem to be extention pieces

Pertaining to posts in this thread other than the quoted one. I am under the impression squish is the area above the piston at top of stroke not in the dome. I fail to see how mounting a compression release would alter that. Another alternative would be to fit the head or a spare on onto a face plate on a lathe and make the dome larger and space the spark plug accordingly. Would a 390 head do this and fit on a 360? It works for a water cooled 430/500 and seems to fit up for the air cooled 430/500 stuff I have so long as I don't use the latest air cooled 500 cylinder.

 

[NZHusky]

I worked for Victa for 5 years as a serviceman and have seen the deco valves drop the little circlip off the end of the valve and have seen the end fall off where the circlip fits.
Needless to say the valve ends up in the engine.

Sorry but your wrong, there is only a fine hole into the heads combustion chamber unlike a lawn mower...so if the circlip drops off the valve blocks the hole in the head, the valve unit does not protrude into the combustion chamber,checkout some of my photos on the link above, the black head is a late model 2stroke Husky part.....same decomp valve!

 

[sweenster]

I worked for Victa for 5 years as a serviceman and have seen the deco valves drop the little circlip off the end of the valve and have seen the end fall off where the circlip fits.
Needless to say the valve ends up in the engine.

thanks for the "heads" up!

 

[sweenster]

I consider anything between top of piston and underside of cylinder head @TDC to be compression or "squish" area. Anything more technical than that will certainly (i would guess) have a more technical term than "squish". anytime you alter this area, as with adding a compression valve, you mess with compression or squish area. mess with area, mess with air fuel mix...

 

[sweenster]

Go for a cable operated one as fitted to British and Spanish trials bikes , never heard of one of them going the wrong way

@stormer254..LOVE your member picture! EPIC!

 

[dukkman]

Sorry but your wrong, there is only a fine hole into the heads combustion chamber unlike a lawn mower...so if the circlip drops off the valve blocks the hole in the head, the valve unit does not protrude into the combustion chamber,checkout some of my photos on the link above, the black head is a late model 2stroke Husky part.....same decomp valve!

If you do what NZHusky has done then you will not get the problem I wrote about.
Cheers Mike

 

[dukkman]

Could you clarify what one gets when ordering the item you linked to. I see that you get a pair but the picture shows three with the center one different. The edege ones perhaps seem to be extention pieces

First lot are extensions.
Second lot down "$38 ones" left hand side sets [ pn 4361] are in the air cooled 430 photo and right hand side sets[ pn 3691 ] are in the water head photo and PE photo.

Note* These are manual deco's which have to be pressed down to work where as the one NZHusky is using is automatic.