bbdropshot
ArboristSite Lurker
So why does a saw 4 stroke, and why does it clear up when you put a load on it.
So why does a saw 4 stroke, and why does it clear up when you put a load on it.
The fourstroking gives me a sigh of relief when deep in wood and lifting to check how she sounds. Usually means safe, and safe means no repairs!
Four stroking is like a moan from the wife at just the right moment, you typically are doing something right!
Saw safe.
what exactly is saw doing when it 4 strokes
So why does a saw 4 stroke, and why does it clear up when you put a load on it.
It doesn't actually 4-stroke---it cant because it's a 2-stroke.
Just give "the sound" of 4-stroking because...it's running RICH mixture.
That's a good thing as "lean condition" can siege (lock up) the piston.
So off throttle...you're running safely rich mixture.
When on throttle...if carb adjusted correctly...mixture will be just right.
Should be very brief interval...second or so...from "blubbers" to "clean".
If it doesn't at WOT...how you run chainsaws...you're too rich.
Got to find the "happy setting"...but better rich than lean.
At WOT you're opening the air supply to carb throat...so all air is let in.
Also NEVER just gun--release...gun--release the throttle trigger....
what---your saw won't idle?? This is Not a guitar solo...you're just putting extra pressure on your clutch bearing...which only turns while you're idling.
Ease up to clutch engage...then WOT...and then cut wood.
Hit that throttle hard and bearing can't release fast enough...just takes a "whollop".
Not good...just add to throttle to engage clutch...then Wide Open Throttle...and CUT !!!
Hope this link helps to explain 2 cycle running although "4 stroke" sound.
http://www.madsens1.com/saw carb tune.htm
J2F
Isn't it suppose to burble at wot and not clean up till you put a load on it?
tdi-rick That makes sense. At 13+ thousand rpm the spark plug would have to fire close to the bottom of the stroke in order to meet the piston at TDC with the compressed air-fuel mix. And without some kind of mechanical timing advance(weights inside a distributor) that isnt going to happen. At least I think so anyway!
I think most will agree, the engine is getting ignition on every second cycle.
Why? :dunno:
I think engines run better under load when rich, and better lean when no load.
So in my mind, that is whats happening...
but again... why? :dunno:
I'm hoping some of the racers on here will have some answers.
Not quite, you don't need that much advance
If you did, karts wouldn't run at their 22,000RPM under load.
What Timberwolf described is a partial burn with no load at a given amount of fuel/revs, not an out and out misfire which is how I've described it previously.
Place the engine under load and the excess fuel is suddenly the right amount for the load and revs in the cut.
[snip]
Iz under the impression that a 2 stroke fires ever time. But i aint for sure.
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