February 22, 2011. to keep the head from warping. I was just looking at another new decompression valve with this description: "Husqvarna part No. A decompression valve will reduce compression during start-up and allows you to pull the starter cord with less effort. If your decompression valve is not working you might have a hard time pulling the starter cord on your chainsaw, cut-off saw, or trimmer. JIMS Manual Compression Release Valves. Replacing a damaged or worn out decompression valve can avoid further damage. Too much valve lash (and it doesn't take much) will cause the exhaust valve to not do its 'bump' opening, thus rendering the compression release inoperative. It's a slight raising, or bump, on the lobe of the camshaft. The valve lash is typically only .004" to .006" on these engines. Upon engine start-up, the compression release re-engages, and the engine once again builds up the required compression to allow it to run and produce power. The compression release is too short to interfere with the valve even when fully extended, and hopefully there's enough "meat" left around the C.R. This top-grade product is expertly made in compliance with stringent industry standards to offer a fusion of a well-balanced design and high level of craftsmanship. 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. Question I just bought an 075AV and it was delivered without a compression release. 503 71 53-01 fits all the standard model Husqvarna chainsaws, also useful on modified modern Stihl chainsaws with high compression because they have a higher release pressure than the standard Stihl valve." Most of the overhead valve engines have a compression release feature that allows for the starter to not have to work hard to crank the engine. I've been screaming out for someone to install a compression release valve in the cylinder head of the Chinese 2-stroke bicycle engines, especially when used with the SBP Shift kit Below is a commonly used compression release valve used in many chainsaws. It seems like this thing just has way to much compression! First thing to check in your situation is the valve clearances. Then the compression pressure, of the compression stroke, leaks out through the partially open exhaust valve. This allows you to kick the engine over easier. Sale. ¶ A compression release allows you to ease the piston over Top-Dead-Center of the compression stroke. Mar 18, 2017. This is usually done by a lever that prevents the exhaust valve from fully seating. Motorcycle Specific. Compression Release Valve by Kibblewhite®. What it does is open the valve a little early to allow excess compression to bleed off. Compression Release Valve • KPMI® Compression Release valves are state of the art and priced competitively • Designed to reduce “hot start” issues and starter / battery loads • 5-7 Newtons of closing force resistance, for high demand applications HarleyT Tree Freak. $127.99 $115.19 Gold Club Price Free Shipping ★ ★ ★ ★ ★ 9. HarleyT. Joined Dec 6, 2014 Messages 17,945. Mar 18, 2017 #4 Take a peek at the piston top through the plug hole, look for carbon or other buildup, or else take off the muffler and take a peek at the piston that way. It has been removed and the hole plugged. The compression release allows the operator to purge the built-up compression or pressure out of the cylinders, making the engine very easy to turn over and start. Manufactured from industry-leading materials using up-to-date equipment, it ensures everlasting reliability and enduring value. Much compression I just bought an 075AV and it was delivered without a compression release ensures reliability! 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