The Forestry Forum

I picked up a MS 171 for cheap. It has minor scoring in cylinder but decent compression. For the life of me i cant get spark. Replaced two new ignition modules. Disconnected wires to rule out ignition switch. HELP?

Well you have a good test bed right there, I mean it's got to be either the module, or the flywheel which is rare to be honest.  Make sure air gap is set correctly as well.

You sure you just can't see the spark, I struggle to see spark now I'm of a certain age.  And I don't mean to offend by saying that.  Also assuming you changed the plug as well, even if it looked ok?

Hold on to the end of the plug and try. You'll at least feel if anything is going on at the end of the plug.

That use to be my go to method to check check for spark. My cardiologist has advised me my defibulater/pacemaker might not like it. Any volunteers to grab the lead while i pull?

I was helping a friend with his chainsaw last week- weak or no spark, won't run. Tried two different new coils, neither worked. Took coil from another running saw and it runs. I think some sellers are selling coils that fit but are not up to specs.