guysmiley
ArboristSite Member
So I got my hands on an old what I believe to be 075AV. Prior owner never ran it and from what I gathered it hasnt run in a long while. Traded a good running 034 super for it as I have been looking for a big saw to round out my chainsaw family.
So I scoured the threads and ran the serial # on it telling me it was a 1975 +/-1 year build. The badge shows no hint of a model... so going by the side oil fill, manual oiler, and presence of the taller carb mount (ends in 01 vs the stihl 051 mount which ends in 03) I am fairly certain it is an 075. Which is contrary to what the last person who ran it was thinking(was told it was an 051) but anywho.... here it is.
I looked at the piston which is in immaculate condition. I put a touch of oil in there and man it has great compression! I poured a touch of 32:1 down the carb and got it to pop. Replaced the dodgy fuel line. choked and pulled.... all bark, no run. Decomp valve works well, w/o it it has nearly dislocated my shoulder. It will run sputter and die which to me is saying no good fuel delivery so I figured a teardown of the carb and general cleanup will be the solution. A bit of pressure washing ( carb taped off) and it is much cleaner. I have ordered a new air filter base with working switch and choke lever (2 things that are kaput now) as well as a lower bushing that was shot. Everything else seems to be more or less ok. Air filter and base are there, just not pictured. Also it has a walbro WS-26A.
So I tear down the carb, clean it out with cleaner and air (everything easy like jets, needle valve etc) no holes in pump diaphragm.... I thought for sure it would run. (also it came to me L@ 5/8 turn and H@ 1 1/8 turn. I turned L to 1 turn and H to 1 1/4 and reassembled). Fuel will get sucked up to carb, I used a few splashes of fuel down the carb to hurry it up. Manually operating choke and utilizing trigger lock.... still same exact symptom but slightly better. It will come to life, idle for a second and then sputter out regardless of throttle input. Gut feeling is carb is not delivering enough fuel, maybe stretched out diaphragm so I tore it down and tweaked the metering lever to get some more fuel with no improvement. There was a brass filter housing? with an o-ring around it.... I am not familiar with that part but the o-ring does not make a great seal as it is able to just fall out if turned upside down. I did not swap the oring out. Also there is a brass screw on the outside of the carb body (if I remember correctly, will include pics later if needed) that seemed to have a sealant applied to it, I did not mess with that.
So here I am, all thoughts are welcome. I figure I couldnt go wrong with getting a new carb. Maybe a Tillitson? Good to have a backup but it would be great to get this one working. Also looks like the saw has a points delete trigger installed. With it's ability to rev up for a second until it dies I believe the ignition and compression and timing are all there. Also I am making sure kill switch wire is not grounded out during all of this.
Thanks in advance!
So I scoured the threads and ran the serial # on it telling me it was a 1975 +/-1 year build. The badge shows no hint of a model... so going by the side oil fill, manual oiler, and presence of the taller carb mount (ends in 01 vs the stihl 051 mount which ends in 03) I am fairly certain it is an 075. Which is contrary to what the last person who ran it was thinking(was told it was an 051) but anywho.... here it is.
I looked at the piston which is in immaculate condition. I put a touch of oil in there and man it has great compression! I poured a touch of 32:1 down the carb and got it to pop. Replaced the dodgy fuel line. choked and pulled.... all bark, no run. Decomp valve works well, w/o it it has nearly dislocated my shoulder. It will run sputter and die which to me is saying no good fuel delivery so I figured a teardown of the carb and general cleanup will be the solution. A bit of pressure washing ( carb taped off) and it is much cleaner. I have ordered a new air filter base with working switch and choke lever (2 things that are kaput now) as well as a lower bushing that was shot. Everything else seems to be more or less ok. Air filter and base are there, just not pictured. Also it has a walbro WS-26A.
So I tear down the carb, clean it out with cleaner and air (everything easy like jets, needle valve etc) no holes in pump diaphragm.... I thought for sure it would run. (also it came to me L@ 5/8 turn and H@ 1 1/8 turn. I turned L to 1 turn and H to 1 1/4 and reassembled). Fuel will get sucked up to carb, I used a few splashes of fuel down the carb to hurry it up. Manually operating choke and utilizing trigger lock.... still same exact symptom but slightly better. It will come to life, idle for a second and then sputter out regardless of throttle input. Gut feeling is carb is not delivering enough fuel, maybe stretched out diaphragm so I tore it down and tweaked the metering lever to get some more fuel with no improvement. There was a brass filter housing? with an o-ring around it.... I am not familiar with that part but the o-ring does not make a great seal as it is able to just fall out if turned upside down. I did not swap the oring out. Also there is a brass screw on the outside of the carb body (if I remember correctly, will include pics later if needed) that seemed to have a sealant applied to it, I did not mess with that.
So here I am, all thoughts are welcome. I figure I couldnt go wrong with getting a new carb. Maybe a Tillitson? Good to have a backup but it would be great to get this one working. Also looks like the saw has a points delete trigger installed. With it's ability to rev up for a second until it dies I believe the ignition and compression and timing are all there. Also I am making sure kill switch wire is not grounded out during all of this.
Thanks in advance!
I looked at the impulse tube (clear) and there was bits of muck there as well.
