HOW THE COMPRESSION RELEASE WORKS ON MOST SMALL ENGINES
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- เผยแพร่เมื่อ 26 ก.ย. 2024
- Today We look at the decompression release on a camshaft in a 14.5 hp Briggs & Stratton engine#SmallEngineMechanic #Briggs&Stratton #CompressionRelease #LawnmowerRepair #LawnMoreMechanic #LawnmowerMechanic
I'm 55 and I have wondered for years how the decompression mechanism works - you would not believe how happy I am to finally understand how it works! - Huge thanks for the video
Dozens of yt videos with small engine compression release explanations - this one is BY FAR the best. Thank you!
Concise explanation without all the blah blah blah. Thank you!
I'm taking an internal combustion engine class in college for an ME degree (senior year). Your explanation cleared up more in 5 minutes than an hours worth of textbook digging and google searching could. appreciate ya!
Good video Jeremy. This should help people that don't understand how it works!
now I finally understand what this decompression valve is on my 84 Suzuki LT185. I've looked all over the net and this is the most detailed easily understood explanation of this topic. Thanks!
Thanks so much. 2:33 was the hit me over the head ah ha moment for me. I heard it explained many time but, your visual brought it to light for me. Thanks again.
Been a machine for 35 years that is a verry good explication of how compression release works and i did know B/S had that in the small engines. thank you J C
@@skatkat6885 I know some people are "machines", never met one that admitted it though.
I have a Kawasaki Fc420v, trying to start it, I would have my arm ripped out of its socket. I then realized that the valves needed adjustment. It was that mechanism that was giving me the problem! Thank You for the great video!
WOW!!! Finally someone, you, explain how these things work. I never knew .. Thank you
Excellent Jeremy! I understood the concept, but, had never seen the exact detail in which the ACR worked before! Thanks again!
I've just started watching you in the last few months. Awesome. Thanks
Allways wondered what that feeling of release was when I put my small engines at TDC for storage! Awesome vid!
Awesome, informative, no BS video! I’m definitely going to start using “Like Yay…” in daily life!
I only had a basic understanding of compression releases on small four stroke engines. Thanks for explaining that.
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I have the same Intek 18.5 HP engine that is in the video. Adjusted the valves at top dead center, and the engine was hard to start. Had to rotate engine by hand just past the compression stroke, and then it would start, and it ran good.
Adjusted the valves again at 1/4 inch past TDC, and bam it cranked right up every time. That 1/4 inch was the difference between hard to start, and cranking right up like it's supposed to do. I reckon the 1/4 inch past TDC has something to do with the compression release.
That same thing happened with my Briggs V-twin 22HP. Re-adjusted the valves by going 1/4 inch past TDC and worked. Started right up no problem. It won't crank past the compression stroke before doing this.
Thanks snippits75
I am working for the first time on a Briggstratton CR 950 and was confused with the exhaust valve because it opens a little bit and it sucked a little air and then opens all the way and discharge. Thanks for this video I learned way.thanks
I knew the exhaust was opening early but did not know why, you told me and it was so simple once you explained, many thanks now subscribed. PS I'm was a body panel man, not a mechanic until retirement.
Well damn, I knew how the decompression worked on a big chainsaw but could not figure out how it worked on a larger mower engine... now I understand what people meant by "the bump". Thank you!
Great explanation and demo. I have a vanguard 18hp that runs perfectly and strong, but if it doesn't start on the first pull, then the second stroke you feel on the second pull can break the cord. Then it starts every time at least on that third pull if it didn't on the first. Hoping it's this, and I can live with it. Nice to know how they work now though.
Thanks for this video. A Gorilla couldn't pull the start cord on my new Honda engine. The service manager had me draining oil and pully the sparkplug before I came across your video. One hit with my rubber mallet apparently dislodged a stuck relief and the engine started with one pull. The engine was shipped to me and I suspect the relief moved. The engine has been starting easily since. Thank you very much!
Good video now I understand a little bit more about how compression release works, I've been having the worst time with too much compression and in my riding mowers for the last couple of seasons. I keep readjusting the valves and they will run normal for a while but it doesn't last and I'm thinking it's got to be something else...
Your videos are awesome as always !! Been watching you for years
I thought for sure there was something off about my cam. This explained it. Thanks a bunch!
Thank you. This is the only explanation I've seen of how compression release actually works.
Very clear and concise.
Great explanation MM1, and perfect timing have one in the shop now that I suspect has a bad compression release im going to show this video to my customer to help explain whats going on.
okay, thanks. I have a Coleman Powermate 6875 that takes about 35 pulls to start. Once it's starts it runs great. But I noticed it gets easy to pull just before it's going to start. So this sounds like the compression release to me. Thanks!
Thanks I wondered for years you cleared it up for me in a few minutes
Thanks, when I putting my Honda GXV140 crank shaft/timing gear back together I couldn't figure out the temporary hang up as I was turning the crank. Now I know.
Thank you for your timer brother, My mower and i watched a lot of compression videos trying to fix it but this was the first showing what the hell makes it not work in the first place. Hopefully i can get it to run now that I know how it works
Thank you. Great explanation. Now I know how it works and finally can fix my little 15 hp Honda.
👍👍👍
Very good explanation and video, thanks!
Great explanation 👍
Jeremy very good demonstration. Big 👍 # 159
Stay safe, Joe Z
Great explanation mate 👍
This was happening to me, it turned out to be a weak battery. It wasn't amping the starter enough to turn it over. I jumped it from the car battery, and it ran just fine. Just in case someone is checking off the easier fixes first before pulling the engine apart 👍
Thanks for the short & sweet show & tell. Really helps me understand.
Great. I have an old sears mower, probably 20 years old. 5.5 tecumseth i belive. It does appear to have that compression release. I had it appart to fix a broken camshaft. ( yes i tig brazed it back together. ) i thought it might be something else. But when you described how it stops, it makes sence. Ill look into to it. Thank you
I love it. Short, straight to the point explained simply. Why some cams have no compression release? Is it for racing? Just got in to small engines not too long ago.
Thanks Jeremy
Perfect! Thank you. Great explanation with visual aids!
Clearer than mud. THX SIR!!! 🤟🤟🤟👍👍👍
Awesome video as usual Jeremy! There's your dinner!!!!
Thanks for the explination
Really useful and concise explanation, thank you!
Thanks for the explanation! I've been trying to get my virtually new generator to run and I think the compression release is staying on. The unit is 2 years old and has less than 5 hours on it. I have only run avgas in it, no ethanol. I tried ethanol mogas because I thought the vapor pressure on the avgas might be too low, but that didn't help. It has spark, but I changed plugs anyway. Disassembled the carb, sparkling clean, but it feels like it's spitting air back out the air intake when cranking. After cranking 10-15 seconds, it drips fuel out the air intake. Manufacturer recommended complete new carb. Same result, so they sent another complete new carb. Same thing. Fuel shutoff on carbs work, oil pressure sensor has been plugged and unplugged. Crankcase vent has been disconnected from carb as it may have been the source for air spitting back through carb, but that didn't help, either. Checked valve clearance and one intake was tight. Set it to factory spec of .006" and no change. It will sputter a little if you pour gas or starting fluid directly into the intake manifold with the carb removed. I'm thinking either a sheared flywheel key or compression release not releasing. I hate to tear into the crankcase on an engine with only 5 hours. Do you know of a way to test the compression release without disassembly? This is a Champion 12000 KW generator, #100111. Thanks!
Thanks for teaching. You are helpful.
Excellent! clearly explained how an automatic compression release works. I have a newbie question, why is there a need to release compression at that very moment and for a given angle? If someone posts an answer I will greatly appreciate it.
Its sole purpose is to make the engine easier to crank. So you can use a smaller battery, starter, etc. while at the same time running a higher compression engine which will have more power/efficiency.
Yep, I learned something again.
accuracy is everything & he didn't make anything up. good info !
Thanks, I get it now.
Huh, i have yet to pull apart any of my briggs 190cc motors and all 3 run a compression release. Now i know what it is and how it works. So there is no sacrifice at all, its soley to start the engine. Really cool. But i was looking to see if i can rig a compression relief for the 66cc chinese motorized bike engine on my bike. Around 600 to 800km it gets extremely hard to turn the engine over due to higher compression from the rings seating in tye cylinder. Once started it runs fine.
It` a nice tutorial! Can you tell whether smaller Briggs engines have the same system, please? We have 7.25HP on our mower. According to its parts list, camshaft5 is made of green in color plastic (excluding its axle only :) Thank you
Lololo that cam is much better than the new ones 😅
thanks. my brand new honda hrx is having issues with the compression release, ugh!
Yeassssss this is this video I need why dont Yu have millions of views
Thanks friend,
Great video, and very clear explanation as to how that slinger lifts the valve....Thanks!
May I ask - in you experience, how far out of adjustment would the valves have to be, to make it hard to start? If they were out 0.001-0.002" would that make it hard to start?
Can we rip this out and replace it with just a pull lever that operates it like on a diesal tractor?
Everyone loathes these automatic compression releases that fail fail fail.
Great video Jeremy
Good video thank you
Nice. Thank you! Question resolved!
I've replaced a broken one and one that was worn just enough to not provide enough of a release or bump to get it to start. I believe they had quality issues with who or how they were built. Both of these were near the 500hr mark.
Great demo :) thanks!
Bet ive watched 50 videos on this,thanks for showing how it works,now i see, say the blind man
I have a 04 Titan Sidewinder with a compression release valve the one on rear cylinder is stuck in there a quick fix to unstick it without taking off cylinder head?
What is the decompression actually for? And is it needed ?
My question is are the replacement cams from Briggs built stronger (thicker pin) than the old ones? I know the cheap knock-off ones aren't any good.
Thanks yes
Great explanation Thank you.
What are signs that the compression release spring is broken
Hard to start even if the battery and starter are good. Rotate the engine by hand just past the compression stroke, and then start it. Might take a few tries to get it cranked, but it will crank. Also, use starting fluid, and then rotate the engine by hand just past the compression stroke.
i have a 12hp briggs and just pulled out the cam . this engine ran ok full speed but like crap idle or hi idle . what i found is the intake valve was being held open thru the entire compression stroke just slightly but on top dead center it would close tight and clearance is .005 . is the cam lobe ground wrong ?
Question sir, my 18 horse briggs,, my compression release is not broken, will worn lobes on cam cause me to have to adjust the valves every time I mow?
Awesome!! I'm gonna tell my customers to watch this so I don't have to explain it to them Lol Great video thank you
Brilliant. Thank you
I read on an old lawn mower forum from 2008, that the Briggs and Stratton Van Guard, single cylinder engines, had the decompression release machined into the crankshaft and that it worked very well, and made the engines last a very long time. The guys talking on the subject said that Briggs and Stratton had gone to the present camshaft release "lobe" as a cost savings move, but that the In Tec engines, the ones with the faulty set up, were terrible and had a bad reputation for failure. Do you know if that is true? Excellent video, by the way.
Is it on the intake valve ?
Very helpful, thank you Sir
This is Sergey I like your videos how many compression releases have failed in your time of them have failed
I think my 1977 Sears lawn mower with the 12 HP Tecumseh engine has compression release but I'm not sure. Does it have it??
Thanks
What if theres a centrifugal compression . I have honda clone 196 on mini bike and after governor was taken out after plastic plug fell out. Its been hard to pull
I usually file down the end of the valve stem to make the valve close for higher compression. I never trusted the compression release. All you do is hand turn the engine and watch the valves cycle through the 4 stroke process. Between bottom dead center on the intake to top dead center compression, you'll notice how the valve remains slightly open to allow the easier pull starts. It wastes a bit of gas plus emissions that are being banned in future, and at normal operating speeds it still runs underpowered. Once you max the compression 60psi-80psi, you might blow the muffler apart.
I have a Subaru EX-40 engine. Had slight knock, I disassembled the engine and found the decompression release lever broken. Would it cause a knock?
can you tell me if the 708cc toro Japanese engine has similar releases? can't find answers anywhere.
Can a broken cam release make a clattering noise? Thanks
I got a question sir :) On a CG200 motorcycle engine will an aftermarket cam gear with decomp help relieve a kickback problem on my kick starter ? I gotta say my right leg sometimes hurt when my damn motorcycle kick starter kick's back 😵💫
Great job !!
I have a 16 ph Briggs engine, and unless it spins really fast the engine back fires through the intake and exhaust and will only start on a battery with a full charge. Could this be a bad camshaft pressure release causing this issue?
Thanks bud
Look Ma, no plastic on this one!
Can you actually grind the higher spot Down a little to make up clearance????
Can that pin be ground down on a mill so it does not come in contact with the tappet? Is there a danger in doing this? How important is it to release the compression on the engine before it starts or does this make it easier on the starter to turn the motor over. Seems like a dumb design.
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Can you buy just the decompression parts without buy camshaft?
Thanks!
I have a 17.5 intek that's got no compression. It never smoked, it just stopped runnin. I took the plug out, put my finger on the hole and hand turned the engine. no compression what so ever. I put a rod in the plug hole and the piston is moving. the only noise it makes is a hiss inside the engine. Could the compression release be stuck open? The hiss is only on one of the strokes. I also set both valves at .004 and am sure the cam, rods, rockers, and valves function properly and the valve guides are set properly..
Stuck valve
@@THEMOWERMEDIC1 slipped valve seat. I put it back in, set it in the head like diamond-setting with a punch, relapped the valves and reinstalled it. Runs fine.
I have less than 400 hrs. on my b&s 1 cyl. and i have that symptom. Is this typical? Seems to me it should last longer.
Just subbed! If a two stroke chainsaw doesn’t have a compression release button then how does it work?
Have a GX270 Honda engine that was running perfectly, shut it down tried to restart and no compression. This engine is not that old and was starting first pull, could there be a problem with the decompression????