Stihl 066

[Sean Lynch]

I have a 066 that I use with an Alaskan MKIII for planking. I don't use it that often but every once in a while when I get access to some good trunks.

Recently a friend had a nice maple that he was going to let me take. Halfway through the first cut the saw died completely. I took it home and checking it over I found that it had a bad ignition - if I check continuity between the metal housing of the ignition and the other lead it's a complete circuit (so it was like the thumb lever on the handle was forever set to "Off"). I figured this was good because it's an easy fix. I ordered the new ignition.

After putting it in, the saw still won't start. It basically doesn't even turn over although I did get a slight firing for about a half second. So then I checked... compression and vacuum is good, spark is good, leak testing the carburetor is good. The only thing I notice seems very minor. There's some fuel leaking from the gas cap. And I notice that the gap between the flywheel and the ignition is different on either side - meaning if I set the gap correctly on one side it will be about twice that if I rotate it around to the other side.

And now I'm getting to the end of my small engine knowledge. Any ideas? I'm thinking if the compression is good and I get a strong blue spark, then it has to be the fuel. But I don't know where to go from here.

 

[Ozhoo]

Welcome to AS. Which combination flywheel/ignition are you running? Have you checked the woodruff key?

 

[djones]

If the gap differs as you turn the flywheel, you also have to consider a bent crankshaft, but check the key first.

 

[sugarbush]

if you have a good spark, try this, with plug out ignition off and no choke pull starter over 8-10 times to make sure your not flooded. saw upside down.

 

[Mad Professor]

I have a 066 that I use with an Alaskan MKIII for planking. I don't use it that often but every once in a while when I get access to some good trunks.

Recently a friend had a nice maple that he was going to let me take. Halfway through the first cut the saw died completely. I took it home and checking it over I found that it had a bad ignition - if I check continuity between the metal housing of the ignition and the other lead it's a complete circuit (so it was like the thumb lever on the handle was forever set to "Off"). I figured this was good because it's an easy fix. I ordered the new ignition.

After putting it in, the saw still won't start. It basically doesn't even turn over although I did get a slight firing for about a half second. So then I checked... compression and vacuum is good, spark is good, leak testing the carburetor is good. The only thing I notice seems very minor. There's some fuel leaking from the gas cap. And I notice that the gap between the flywheel and the ignition is different on either side - meaning if I set the gap correctly on one side it will be about twice that if I rotate it around to the other side.

And now I'm getting to the end of my small engine knowledge. Any ideas? I'm thinking if the compression is good and I get a strong blue spark, then it has to be the fuel. But I don't know where to go from here.

You are only concerned with the coil gap between the coil and the magnet portion of the flywheel, set the gap with flywheel magnet adjacent to coil. It should still turn without contacting the coil 360 degrees.

If you have spark, is the spark plug wet or dry?

Wet and it's flooded, clean plug, pull over to clear crankcase w/o plug, then try starting again. If it pops and floods a carb problem, check the needle and diaphragms, make sure choke is not shut. If it don't pop and plug is wet again back to checking ignition.

Dry and you may have a fuel or vacuum problem. Try adding a splash of mix into the carb and try starting. If it fires track down fuel or vacuum problem. Try easy things first like fuel tank vent, fuel line/filter, carb diaphragms/screen/metering needle, impulse line. I don't always just rip a carb all the way apart without checking over the diaphragms/needle/screen. Sometimes it's just sawdust packed behind one of the carb covers, a clogged screen, or stuck needle.