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Three year old Redmax BCZ trimmer what kind of compression?

Discussion in 'Mechanic and Repair' started by kubotaorange, Nov 14, 2011.

  1. kubotaorange

    kubotaorange LawnSite Member
    Posts: 47

    What kind of compression should these be producing. Right now this particular trimmer has a lot of hours on it, and I was getting 90psi with my compression tester. Is this adequate? It starts and runs, but takes awhile to warm up and it just doesnt scream or rev up like our newer trimmers. Did all the routine stuff like exhaust port/sprark arrestor, new plug, fuel lines, etc.
  2. dutch1

    dutch1 LawnSite Silver Member
    from Jayhawk
    Posts: 2,231

    The real 2 stroke guru's may disagree with my assessment, but I've normally considered the low end to be in the neighborhood of 100 psi. I seen 90 psi stuff that would not crank on carb/choke cleaner and some stuff at 100 psi that wouldn't perform at a level I was satisfied with. Depends.

    The only solid info I have in hand is some Echo technical data from 2002 when I was still working in an Echo/Shindiawa shop. Most of Echo's product specs the compression from 115 to 150 psi, depending on equipment. Don't know much has changed in the last 9 years but I wouldn't think it's significant.
  3. kubotaorange

    kubotaorange LawnSite Member
    Posts: 47

    Thats what I'm thinking, 90 seems pretty low. I've got to believe she's just getting pretty worn out. May be time to retire it or throw some new rings in it.
  4. kubotaorange

    kubotaorange LawnSite Member
    Posts: 47

    just bumping this one back up to get some more opinions.
  5. pugs

    pugs LawnSite Gold Member
    Posts: 3,022

    If it has less than 100psi I dont even mess with it. Even right at 100 would be on the low side. Check for scoring in the cylinder.
  6. all ferris

    all ferris LawnSite Bronze Member
    Posts: 1,307

    hone cylinder, new rings, head gasket = good as new
  7. kubotaorange

    kubotaorange LawnSite Member
    Posts: 47

    what kind of hone? i've heard that brake piston hones may work, but I don't know if that's true or not.
  8. Saw Dr

    Saw Dr LawnSite Member
    Posts: 9

    I have yet to see a piston-port two stroke that will run at less than 100-110 PSI. Does your tester have a check valve at the tip? I suspect you have more than 90 PSI, and you tester is reading low.
  9. kubotaorange

    kubotaorange LawnSite Member
    Posts: 47

    My tester works fine on all the other equipement I've used it on. I've tested this one particular trimmer a few different times and 90psi is what I get each time. I tested a new backpack blower we got and it had 135 psi, then immediately checked this trimmer and it came up 90 again.
  10. kubotaorange

    kubotaorange LawnSite Member
    Posts: 47

    pulled the trimmer apart today, it's got a stuck ring. going to clean everything up and replace the rings and see what I get.

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