Could someone please describe type of tach ( photo, inductive pickup or otherwise) used to read saw engine rpm and some detail on procedure.I have access to the tools and know how to use them. I got a Stihl of a deal on a 066w and have checked it over thoroughly and it is in excellent running order. Reading posts here has made me aware of the fine line between mixture and rpm on these engines. Excessive rpm is a sure sign of over lean; correct? I cannot tune this saw by ear as some might and would hate to burn the cylinder,rings or piston simply because of a mis-adjusted jet.I know the inlet is sound but cannot speak of the case seals.This must pertain to the vacuum/pressure checks I hear speak of.Bottom line, saw is new to me, runs well and I would like to check max rpm as this is a reflection of mixture.Please chime in if you can .
Yes, to lean is to fast, to a point, but destructive
A digital tach seems best, you will need something that can read 15K .
What I would do is hook up the tach, run the "H" jet out to a good 1 1/4 - 1 1/2 CCW* from all the way in (you need to cut the tabs off the limiter caps, do a search) start the saw (bar and chain adjusted like your going to run it, no sag, no drag) on a good mat or log/stump, and bring it up to speed, at about half throttle your going to know if your too rich and it is not responding much to the trigger, or it is progressing nicely?
Watching the RPM"S, hopefully it will wind out to maybe 10 - 11K (give or take) that's good, turn the "H" in just a tad, and retest, when it retest a a constant 13K, sink it into some wood! I been cutting at 9,500 feet, and 13.300 is a good out of wood speed.
An occasional burble out of the wood, but clears up in the wood is about as close as I can get it.
*If everything is hunky-dory, about 1 turn out is about were you will end up,,,, @ 1 1/2 turns out, it will run a safe , fat/pig-rich speed, adjusting in from fat seems better then out from destructive.
