After three times using it … He always had something to do or fix and would always get round to doing it. Most 2 cycles need a minimum of 100psi to run, some will run with less, some won't. I have a Homelite 20" 2-cycle chainsaw that's 2 years old with about 2 hrs run time from new. Just had the saw running five minutes before this condition started so I'm thinking the flywheel key isn't broken. Enjoy the videos and music you love, upload original content, and share it all with friends, family, and the world on YouTube. Hey thanks much, the comments section filled in the blanks too, like whats the bare minimum of compression needed before an engine will start, and that's 75psi – 90 is a worn out engine. We have explained that later. Having a hell-of-a-time starting...compression seems much too strong for the pull cord. I've got a big ol' Jonsered 801, 80cc, no decompression valve, and it can be a beast for me to start sometimes. ... in where a hot engine will ask more than 160psi compression range from the vacuum air. I built a clone Stihl saw ms660. Press J to jump to the feed. I have removed the muffler and cleaned it and still nothing. I have a husky 288xp that is exactly the same . To understand the compressor test of the chainsaw, there is a simple test that you can conduct. The hose cracked and allowed air in, making the mixture too lean and causing me to need a new piston. Stihl reviews (www.stihl.com): Can’t start chainsaw. Too much compression on chainsaw. I recently developed a leak in my primer bulb and took my chainsaw apart and replaced primer bulb, fuel lines, and cleaned the carburetor. High compression is usually first diagnosed when the starter rope refuses to pull. just went through my parts manual for the Stihl 034 chainsaw and did not see a listing for a compression release or location. Compression is generated by the engine via the crankcase and the combustion chamber. Next thing is to smell/look at fuel. The other chainsaw is an identical model and has similar problem. Re: Chainsaw has too much compression in reply to Russ from MN, 08-17-2017 21:23:47 Also check the air filters and make sure they are clean. I did this yesterday and got it started once and it ran for a few seconds. My dad died 6 months ago and I have all of his tools and things he was working on at the house. If I can get this chainsaw working for him then I would be very happy. First thing we check is compression by feel. More than likely it's just a high compression big displacement saw, it's gonna be difficult to start. He was good with this stuff, but I didn't have a clue about fixing things and never learned. If I force it and pull it hard it nearly rips my hand off. After three times using it the start cord broke. My small Stihl chainsaw has to much compression, it used to be ok and used to run well before I put it away in a … A quick check is to pick the saw up by the recoil handle, if the saw drops thru the compression stroke, it needs serious work. 2. I will typically cheat by giving it a rich start. Too much compression. With the plug removed it should extremely easy to pull, if it is not my first guess is the clylinder is scoured up and/or bad bearing (s)/bushing. Running a lean mixture for too long will cause irreversible damage to the internals of the engine. I'll set it choked, pull the starter fast a couple times with the ignition off, then pull it over real slow until the piston is just past the top of the stroke to give me as much momentum as I can get, then switch the ignition on and pull hard. The rich gas load keeps it from firing so hard that it stops me dead in the stroke, but still has just enough pop to start it, and it isn't flooded to death. Mr P. Lv 4. Thanks I'll check the pull cord length this week as it's honestly like it's jamming or bottoming out and flying out of my hand. Recently I tried to use it, but when I pull the starter rope, it feels like there is great resistance with every cycle of the piston, like there is too much compression. This is what I look for when repairing commercial equipment and older vintage saws or any 2 stroke engine. I bought 2 032 Stihl saws at auction that pulled very hard. Hi I have a chainsaw which is a Mac Allister 40cc. Question I just bought an 075AV and it was delivered without a compression release. I did read that flooding it can have that effect. It has been removed and the hole plugged. Regular 87 octane is pretty much garbage. You should maintain servicing the chainsaw every time after using it for 25 hours. Re: Chainsaw has too much compression in reply to vsteel, 08-18-2017 07:12:26 No it wouldn't go straight to crankcase because you would spray a light mist through air intake with hot engine and let it run for a while after doing it.You might want to do it with screen removed from muffler. If I turn the saw upside down, I get a drop or two of fuel from the spark plug hole, not enough to lock up the cylinder. Jon. I have a spare sprocket that I am using and have learned now not to force it if it won't pull smoothly. Under reduced compression on a good tight saw the comp is still over 120 lbs, with the comp release closed it should be 140 or over. Try to use or at least run your chainsaw on a regular basis just to keep all its parts active. F-250 5.4 V8 stand. For a fast and easy start of the chainsaw, try to use fresh fuel. He always had something to do or fix and would always get round to doing it. I've bought some needed parts for this chainsaw which include a spark plug, air filter, a fly wheel and key and the body cover. But, just for the sake of an answer, a exhaust valve could be stuck and raising the compression or like one mentioned, carbom build-up. Too hot or too cold engine, will not ask an appropriate compression rate from inside of the engine. The only problem now is that when I try to start it theres a lot of compression and it very hard to pull. But after all of that pulling and forcing the teeth on the sprocket which are plastic wore down, so much that they don't protrude enough to catch the fly wheel. So don't skip arm day. However, these moving parts, to stay moving, require a substantial amount of compression. Recently bought a Stihl MS250-18 chainsaw. The plastic inserts really don't do much other than take up space & thus bump up secondary compression. I need to check if I am hitting the end of the cord maybe it's too short? The symptoms were identical to what you are describing. But if neither cylinder is at spec (remember, you gave us no numbers) it could be worn rings and compression is leaking. It has been stored in my garage w/o starting for approx 10 months. February 22, 2011. Main Hearth Forums. I know a lot of chainsaws have the decompression valve to help start easier but this one doesn't I've checked everywhere. Thread starter hemlock; Start date Mar 20, 2011; Forums. All went well with the build and it was a load of fun. r/Chainsaw: A reddit for all operators of chainsaws to post experience with tools, pictures of their new saws and old workhorses and any maintenance … Press J to jump to the feed. Press question mark to learn the rest of the keyboard shortcuts Chainsaw . The most common reason is due to too many attempts trying to start the machine in the choke position. On some saws I have found excessive wear in the pull start that allowed the pulley to twist a bit sideways and that makes it difficult to pull. 358.360121 16" craftsman chainsaw I am looking for what the normal operating compression should be on this chainsaw. Can barely pull starter rope ... as for "how stiff is stiff" - it is so stiff that I effectively can't start the saw - it is simply too jerkey and requires too much brute/uncontrolled force on my part to overcome the resistance. cab, tandem trailer Ferris IS3100Z 61" L … My dad died 6 months ago and I have all of his tools and things he was working on at the house. The bore should be nice and smooth. 1 decade ago. Read the article to know how much compression should a chainsaw have. i am getting about 95 the chainsaw will not start. My dad got given this chainsaw as well as another one a while ago and since he has died I've been having a go at DIY and trying to fix things as he would of. Can you tell me where the release is located? Honestly take it to a shop, they charge $15-$20 for a compression test and you know where you stand. When starting a unit, make sure to follow the starting instructions in your instruction manual.The manual provides the proper instruction for starting procedures, but there are many conditions that may affect how the unit starts. The starting action prior to this had been fairly smooth when pull starting the rope. Excessive wear around the hole that the rope runs through will do the same. Dissapointed. Having a hell-of-a-time starting...compression seems much too strong for the pull cord. The Internet says to check cylinder and piston for carbon build up which I have and it looks fine, its all shiny with no scratches. Reliability & Customer service. and also, should it be checked with the throttle open or closed? I did not take it apart , but concluded rust must have formed on the cylinder even stored inside as … A reddit for all operators of chainsaws to post experience with tools, pictures of their new saws and old workhorses and any maintenance tips. Get shopping advice from experts, friends and the community! According to Stihl USA, the minimum compression reading for their chainsaws should be around 110 psi. If both the spark test and the fuel test fail, you will need to try a compression test. We use cookies to give you the best possible experience on our website. Will this get easier or have I done something dumb? When the starter feels tight, don't just assume that compression is the culprit. Remove the spark plug and it spins freely. A bad fuel line will cause the chainsaw to run lean (too little fuel or too much air in the mixture), and this means it will only run at idle for 5 to 10 seconds before it shuts off completely. please advise Bottom line is we need more info. 0 0. It took a lot of pulls to get started before I realised the carb was not factory set. Diagnosing the Compression System. Any advice thanks I'm sure I can attach picture. getting fuel,spark tried starting fluid in cylinder,new plug just get a little smoke from it. Press question mark to learn the rest of the keyboard shortcuts. This measures the amount of pressure in the tool's cylinder. Stihl chain saw too much compression I had to take it apart to put in new crank seals so I had to split crank case - Answered by a verified Technician. to much compression on chainsaw? Chainsaw compression. If a saw has less than 100 from the outset then it likely will be very hard to start and flood out easily. Stihl Chainsaw Compression. He was good with this stuff, but I didn't have a clue about fixing things and never learned. A chainsaw engine generates this compression through the explosion of the fuel in the combustion chamber and the movement of the crankcase. 1. Chainsaw Compression Release Explanations of the purpose and value of a compression release valve on a chainsaw, and some advice on starting a stubborn saw with less pull-back on the rope. Pull the muffler, get the piston below the exhaust ports, shin a bright light into the port and look/see. The chainsaw typically sits a year at a time and this year a tree came down and I needed the Husky quick. Remove the spark plug from your tool. The more you use a chainsaw, the quality of the fuel gets worse with time. Source(s): https://owly.im/a85XD. However, I cant pull the starter cord at all now. 120 -145 psi is best. Lawn equipment compression should fall in a range between 90 and 110 psi. so my thoughts is the compression is low. A worn cam would also give you a higher reading. anything really high could be carbon buildup on … Hi I have a chainsaw which is a Mac Allister 40cc. But when I did it's first start it was so stiff with the plug in, that I need to use both hands and have my foot on top of the body. I had a problem at first with the pull rope which wouldn't budge but I sorted it and it work now. The pull was too short too.. New comments cannot be posted and votes cannot be cast. I've tried pulling numerous times rapidly with the spark plug out to get rid of excess fuel and I've tried leaving it upside down to drain out of cylinder. ... You may also have a dead or dying head gasket too, could cause low compression but many small motors have one piece cylinder/heads so this may not be an issue. When compression is too low, you may experience decreased power or complete shutdown because the engine isn’t able to hold enough pressure in the cylinder to run efficiently. It was very difficult to turn over with the compression release. Anonymous. Sad but true,you cant save em all. Once started it runs great. 0 1. 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