mdavisfps
ArboristSite Lurker
Hi all,
My neighbor has a '93 026 which loses power and then shuts off at WOT -- especially after the engine has warmed up. Air filter and exhaust screen are both clear. Don't know about the fuel filter, though. It sounds to me that it's running very lean at top speed prior to cutting off. I put a tach on it and it showed a max of 15,000 at WOT. The original specs call for 12,500. Our local Stihl dealer says that 15,000 is correct for this saw.
First question: Would the engineers who designed this engine endorse 15,000 as a safe max rpm, or is this "correct" only because that's what the EPA folks (and, therefore, USA Stihl dealers) want to see? I just remember hearing that exceeding the maximum recommended rpm could result in damage to the engine. No?
Second question: I've read in a number of posts in this forum that whatever max rpm you have the saw set to, you still want to run just a little bit leaner than when it 4-cycles. Any leaner, higher rpm maybe, but less power. Did I understand this correctly?
Third question: This saw has a hole labeled "H", but no screw head visible -- just a soft, almost fiber-like blockage halfway back the hole. Did this saw come with a high speed limiter and is that what I'm seeing? (My '91 025 has an adjustable "H" screw).
Fourth question: If the saw is indeed running too lean at WOT can this be corrected by adjusting the "L" screw to a richer setting?
Thanks for any information/suggestions.
Mark
My neighbor has a '93 026 which loses power and then shuts off at WOT -- especially after the engine has warmed up. Air filter and exhaust screen are both clear. Don't know about the fuel filter, though. It sounds to me that it's running very lean at top speed prior to cutting off. I put a tach on it and it showed a max of 15,000 at WOT. The original specs call for 12,500. Our local Stihl dealer says that 15,000 is correct for this saw.
First question: Would the engineers who designed this engine endorse 15,000 as a safe max rpm, or is this "correct" only because that's what the EPA folks (and, therefore, USA Stihl dealers) want to see? I just remember hearing that exceeding the maximum recommended rpm could result in damage to the engine. No?
Second question: I've read in a number of posts in this forum that whatever max rpm you have the saw set to, you still want to run just a little bit leaner than when it 4-cycles. Any leaner, higher rpm maybe, but less power. Did I understand this correctly?
Third question: This saw has a hole labeled "H", but no screw head visible -- just a soft, almost fiber-like blockage halfway back the hole. Did this saw come with a high speed limiter and is that what I'm seeing? (My '91 025 has an adjustable "H" screw).
Fourth question: If the saw is indeed running too lean at WOT can this be corrected by adjusting the "L" screw to a richer setting?
Thanks for any information/suggestions.
Mark