All this talk about tuning saws lately has me re-checking my 2 huskies and perfecting the carb settings on my 5100. Once the saw is broke in, what would be considered the max time you should hold the saw at WOT with no load? Obviously there is no good reason to do this other than to check rpms with a tach or listen for four stroking. It just got me thinking. My 5100 has a rev limiter so it cant over-rev. As long as the carb isnt too lean, what problem(s) could this cause?
No load WOT
- Thread starter brent denny
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Simonizer
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Nothing.brent denny said:
bvaught
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Madsens used to recommend that saw tuning be done with bar and chain removed. I removed my bar and chain to tune and while leaning revved my 440 to 16000 RPM for a brief moment. Any chance I harmed the saw?
fishhuntcutwood
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I'll run mine WOT no load, with bar and chain installed just long enough to get the rpms and saw sounding like it should. I'm always eager to get it back down to idle and let it cool off and settle down. I've never hurt a saw running it WOT for tuning purposes. I'd reckon you'd do more damage to a saw running too lean in the cut because you didn't run it WOT to tune it in the first place.
Jeff
Jeff
jp hallman
ArboristSite Guru
bvaught said:
IMO I doubt it. When they go from excessive rpm's you usually bust the skirts off the piston when it hits the crank. Then the pieces of the piston jam between the counter weight and the case. If it still runs I'm sure it's fine. Time will tell!
Simonizer
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Extremely unlikely. Although the load on reciprocating parts increases by the square of the angular velocity of the crankshaft, the time parameters you describe suggest minimal effect.bvaught said:
To put this in AS terminology, "If it didn't go ka-fu**ing-BANG!!", all is well. Cheers.
bvaught
ArboristSite Operative
Simonizer said:
Thanks Simonizer thats what I wanted to hear. The saw still runs like a champ.
pbtree
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bvaught,
no worries, I am sure.
Jeff, good post. I too only WOT under no load to set the carb, and I try to do so only when necessary, as I am sure running a poorly tuned saw will cause more harm...
no worries, I am sure.
Jeff, good post. I too only WOT under no load to set the carb, and I try to do so only when necessary, as I am sure running a poorly tuned saw will cause more harm...
Lakeside53
Stihl Wrenching
fishhuntcutwood said:
I'm with Jeff... I do 5-10 per day just like this. Never have damaged a saw. You never get a saw really hot unless you cut wood (develop HP) but you have to get the saw hot first - I just cover the fan side with a cloth for a few minutes, or if I'm in hurry, cover it with my leg and rev away for a while.
One other trick that errs on the side of caution: Always start at factory default settings (too rich) and tune from there. If the saw won't idle unless much richer (say 1.5 turns out when the factory default is 1 turn), you have an air leak so fix that first. If the high end doesn't run "decent" at close (say 1/8 turn) from default, fix the problem before proceeding...
Lakeside53
Stihl Wrenching
bvaught said:
Next time, turn your H mixture to full rich (with limiter caps in place) before you try to tune at WOT, or, factory default setting with caps removed. This way you won't get to 16,000, or even 13,000 if the carb is working correctly.
Not sure where Madsens is coming from, but tune it with the bar/chain in place, Maybe they are just being "safe"?
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