I just bought a new 550xp Mark II and have about 5 tanks through it with Husqvarna fuel. I’m reading 90 psi, even when it’s warmed up. My compression gauge is accurate. I assume this isn’t normal, but the saw runs and cuts well. What do you recommend?
Husqvarna 550xp compression
- Thread starter sambruin7
- Start date
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So the gauge should 150-160 on all the other saws, did you only pull it a certain amount of times or did you continue pulling until it stopped rising?
It stopped rising, I pulled it at least 2 dozen times or so.
thenne1713
ArboristSite Guru
If true 90psi, surprised it started and suspect you have a stuck ring?
Ok here's the update. The compression tester I am using has a long hose extension, made for large (regular) sized engines. The other husqvarna dealer used my adapter to test compression with his "shorty" compression gauge and read 92psi. I went to another dealer at Rural King who had a 10mm Husqvarna compression gauge (didn't require an adapter) which read 130psi after about 4 pulls while cold.
After reading on this site, someone else pointed out that, "The Schrader valve must be as close to the combustion chamber as possible, especially on small cc engines. Be cautious if using an adaptor, it can increase combustion chamber volume and reduce the compression reading. I just experienced this on an MS171 which uses a much smaller spark plug - the adaptor changed the compression from 130 to 90 psi. I modified the adaptor to keep the valve at the end. "
Tomos770
ArboristSite Guru
That issue was discussed here already.,..
Can you post the link you're referring to? That would be helpful. Thanks.
Tomos770
ArboristSite Guru
Almost every topic wich is discussing low compression readings...
https://www.arboristsite.com/thread...ence-between-high-elevation-sea-level.369479/
https://www.arboristsite.com/thread...ence-between-high-elevation-sea-level.369479/
