Hi,
A student of mine brought in his Chainsaw so I took advanatge of its presence and broke down a big burl someone had donated. The saw seems to start and idle OK but it will bog down in the cut and you have to pull back(no power). The chain and bar are new and in good shape. If I rev it up it will surge up to full throttle and back off some and then repeat without changing the throttle position.
Any pointers?
Thanks.
Dave
Did the student bring it in for repair?
No, I teach woodshop. He just happened to have it and I neededto break down a burl and he let me use it. I would help him make it run better if I could though.
Dave
From my experience, surging is due to either lack of fuel, or lack of air. Make sure that the fuel isn't air locked, or the filter plugged. Also, a dirty air filter is good to check, if you haven't already.
Often times if the saw has sat unused for a period of time for some reason the low speed jet will become partly plugged .As such as it tries to accelerate it goes to a lean condition before there is enough pressure drop over the high speed jet to suck fuel .Usually if you open the low speed just maybe an eighth of a turn it will clear up .
Matter of fact just last evening at my least favorite activity being lawn mowing etc my weedwacker did exactly the same thing .May first and up to that date I refuse to mow grass even if it got knee high to a giraffe .
It seems a lot of old congers like me have a love affair with lawn care .I happen to be of the minority in that stuff and find it a general nuisance .
I tend to relate "surging" associated with an air leak.
On a saw of that age, I would start by replacing the impulse and fuel line/filter, rebuild the carb and inspect the intake boot.
Something that old, it should be done as preventative maintenance anyway.
If it still surges after that....I put money on the crank seals leaking.
I suspect the leaks too but will try Al's and Treedudes advice tomorrow. For some reason he left it.
Quote from: shinnlinger on May 02, 2013, 11:06:58 PM
I suspect the leaks too but will try Al's and Treedudes advice tomorrow. For some reason he left it.
Ever figure out why it was surging ?
Not really sure. I pulled the air filter apart and it seemed to be new but assembled incorrectly and there were chips in the plenum to reenforce my thought so i cleaned it up a bit and I put it back together and fired it up. I tickled the low speed needle as AL suggested and cut up some more burl. It seemed to run better but still surged some. I fiddled with it a bit more but then saw the superintendent walking around and figured running a chainsaw near classrooms w/out safety gear was probably a bad idea so I put it back in the kids illegally parked truck. The student said he ran it later and it was running good, so maybe it cleared it up or maybe the kid ain't as picky as I am.