A simple explanation of how a small engine decompression valve works. These valves are mostly used on chainsaws and concrete saws.
source
(21)
How a Small Engine Decompression Valve Works
Small Engine Repair Videos
Videos about Small Engine and Lawn Mower Repair
@sthier24 Husqvarna is my favorite saw, bur Stihl and Husqvarna i would say are equal in quality
@TrackEmDownKennels sometimes they won't shut properly
never even seen one before so thanks der brotha !!!
I have one on my craftsman chainsaw it went bad a while ago and I am waiting to get the part to fix it . I have not found a way to bypass it by replacing it with something else . My sons 1987 yamaha 350cc had one in the head of the quad and a pull starter there were only 2 years 87 88 that had pull starters and decompression valves.
Enjoyed the video thanks
NOT TRYING TO TROLL BUT THE CASEY ANTHONY TRIAL HAS REACHED A VERDICT PLEASE VIEW ON MY CHANNEL @camden199 much appriciated thanks
Great video, those things really are that simple aren't they ? lol
@richardwernst thanks man!
@IW5Industries learn the basics from my dad in my teens, had a few classes in high school and the rest is self taught
good video explaining an excellent example of innovative minds employing simple and effective inventions that reap rewards multiple time over and above the investment it takes to add.
I am sure this will save many a right or left hand the pain similar to the condition known as plough hand
I have a very old briggsandstratton 6hp engine that is in a golfcart it was in a barn for 15 years i put some money into it and it was working fine. And it was smoking so i drained the oil and put fresh in but and it still smokes and now it just stoped working im only 14 but im really into this kind of stuff could it be the piston rings? and is it worth fixing? Thanks.
It work's the same as compression release valve a lot of snowmobile's had them
I seen a outboard motor that was automatic I pulled on the recoil And I could see
Levers turning it on and off but it had a adjusting nut's for the release valve. They
should make a RC engine for weed trimmers just to see how they turn out.
very nice………….very helpful
gostaria de saber se essa valvula de descompressão funciona para moto husqvarna wr 360 2t.
taxa de compressão alta.
obrigado.
E:mail adivaldo@gmail.com
That is just one "style" of decompression valve. I would like to see other "compression release" systems say on Stihl saws or on larger Honda 4 strokes.
donyboy73 mate you such a legend.I always watch your videos.they are great help..thanks and we look forward
Donyboy73,thanks all the help on your videos, but what is the thread type on the valve, it looks really fine
i think it's metric
Thanks mate, spoke to an engineering nerd- its 10mm metric with 1 mm pitch (if someone ever asks !!!) Take care
Once again Donyboy73 has the answers to my questions, THANKS
Great video as always. I have an Echo weed wacker acting as is it has too much compression to pull could it be a auto decom as it doesn't have a manual one? If so I take it it is a major strip down?
Awesome information. thanks.
hi donyboy
I have a problem on my ts420 cutsaw the decompression valve pops open on every two pulls, i put a new decompression valve and it still pops. The starter rope is hard to pull can you tell me what the problem can be thanks
would you happen to have a video
so what if its easy to pull when its in or out
hey, I have a Husqvarna 335 XPT. It's really hard to start but I don't think it has one of these valves? Any ideas? The exhaust isn't stopped up. It's not flooding. The flywheel key isn't sheered off. To crank it you have to pull it just past the "hard spot" then give it a good yank and it starts right up and runs great. I see the same saw on youtube videos but they are really easy to pull start. I'm going crazy over this damn thing, HELP!!!
I have one on a 71cc 2 stroke earth auger & It's become very hard to pull-start with the valve in or out. I feel no difference on the recoil starter either way.
Do these things ever fail?
How do you test them?
Is the opening direct to atmosphere such that you can blow thru by mouth or with compressed air& actually feel it coming out the other end?
donnyboy, as always, great video.
i have an old victa corsair lawn mower and it too has a decompression valve. however, unlike the chainsaw, it has a tube going to the carbie.
what i want to know is whether or not it serves the same function and is it required (meaing, can i just plug the hole with a bolt if its only function is to ease starting)?
i only ask because i want to turn it into a horizontal mount for a four wheeler.
Youtube for the win.
Thank you for the informative video. I have a saw with this on it and have never really understood the purpose as it starts beautifully without using the valve. I always figured it was to assist in getting the cylinder rotated around for a full cycle to make it easier to start. Thanks again!
Thanks man, that was very informative!
Thanks man its really usefull
will the 55 cover fit the 50 chainsaw? since it has a slot for the valve.
hello, i have a problem with decmpression valve on my husqvarna 357xp, i take it off but it seem is clogg something inside there(the valve is ok)
I wanted to comment after reading this that a lot of engines from chainsaws even riding mowers have that mystery lever or the valve hidden way under some cover you really have to look folks. It's important to save your saw or weed whacker tractor and mower manuals after y'all shop at Lowes and Depot's MADE IN CHINA lawn and tools bins… Read the shit people you may actually learn how your shit is supposed to work what gas and oil to use…. And then there are shops like mine where you get charged you for that re-information because we have to pay the guy $$$ that works for us to re-inform you about YOUR SAW or MOWER…. . Whereas the info in those discarded manuals you lined the cats little pan with or burned in the wood and coal stove……… LEARN ABOUT YOUR EQUIPMENT PEOPLE. BALDE SIZES MATTER SO DO CHAIN and TOOTH SIZES as well as BELTS AND TENSIONER ADJUSTMENTS!!!!!!!!!!!!!! HAVE A FEW CANS OF BEER CALL ME IN THE MORNING WHEN THE BEER FOG WEARS OFF…
While cleaning my Pioneer P20, I noticed it has a decomp valve that is maintained open by a spring and automatically shuts closed through combustion pressure. Very ingenious and a welcomed feature in such an Old (30 years) and small machine. Built in Peterborough, they were good !
Deer Dony i bought chainsaw H445 II but i don't have decompression valve is that a other model of 445 or something else?
Hi FriendAt what size are cc did mcculloch star5t using the compression release. All my saws are late 70's. Thanks Don Jackson
Very well explained Thankyou for the your video.
Nobody can figure out why my TS500I quits running when it's cutting for 10 minutes. Is there a overheat protection temp sending unit? The local Stihl dealership has replaced all the electronics twice. They threw their hands up in defeat.
Nice to have that explained; thank you!
I have the same saw but there is no decompression valve, but i see the place where you can put one . my question is , can you put one ? it looks like you have the option from what i can see . i never saw anyone making a video on that, would be nice to see .
can you please show a vidio of how to install choke wire on a stihl ms391i it,s a old model thanks.
what about weedeaters? i have 2 echo weedeaters, my brain is rusty on this one. when i pull the chord it pulls but the chord freezes like 4 times per pull. i have a bad rib so i simply cant do this i need to fix this. i took the spark plug out and pulls the chord and it glides easyyyyyy.
only a Dumb sweed woukd put a valve in the cylinder wall, instead of over head like a stihl
Thanks Donnie,, hope thats right.Wondered the benefits of the valve.
Thanks for the video, very helpful would a 098 cc 2 stroke have one?
Your shop is freaky neat and clean.