No start on a WeedEater FeatherLite

I have a weedeater with good spark, rebuilt carburetor but no go. Checked compression and seems too low for a 2 cycle engine (at or below 100 lbs). Added a squirt of oil and compression went straight up to 130 plus so I'm thinking bad rings or worst. Anybody have any other suggestions as to where to look?

 

Remove the muffler and look in to the exhaust port. From there you can see the cylinder and piston to tell if they are scored. The featherlites were $58 at walmart... not really meant to be repaired.

 

Thanx, Cheese, yeah, I'll do that tonite.Do you know what the compression is supposed to be on 2 cycle engines? I'm getting mixed numbers. Some say it should at least start on about 90 lbs and some say 125 lbs?

 

There is no magic number because it depends on the speed the engine was turning during the test and other things. 90 psi is low for a 2-stroke, low even for a 4 stroke. I'd say anything less than ~110 indicates problems. 130-150 is ideal. A low-tech way of doing a leakdown test that will tell you a lot about the condition of a 2 stroke is... set the trimmer on the ground. Pick it up by the pull rope handle. If the whole unit comes up and slowly lets down with a "plop-plop-plop" sound and motion, it probably has enough compression and the cylinder/piston are probably in decent condition. If it doesn't pick up, or if it picks up for just a second or two and lets down rapidly with a "slush-slush" sound, it's probably not good enough to start. Pick up a good one to see how it does, then compare to that.

 

Thanks, Cheese, took it apart and sure enough the piston and cylinder are scored pretty bad, so looking for yard sale machine and going to change the head and piston if i find one.