Mowers only- or tings like string trimmers as well?

Ortis

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Hi - I am 65, live on a farm but don't do the farming personally. We do have a good bit to mow and keep trim. For mowers, I have a 50 year-old Jacobson that we have not used in a while, a 21 Horse Kubota, a John Deere 316 lawn tractor, and a 1954 Ford NAA tractor.

More relevant, I also have a Stihl FS-85, 2-stroke-cycle, string trimmer, an echo chainsaw, and other tools with small engines.

The current problem is with the FS-85. It quit, and upon looking into it, I found that the piston was badly scored. So, I bought a piston & cylinder kit, replaced the damaged units, and figured I was home-free. It didn't work out that way. It has good spark, feels like it has compression, and yes I did put gas/oil mix in the tank. It won't even try to start. I even tried ether and got nothing.

Do those symptoms ring any bells to the hordes of users on the forum?

Of course, the most basic question is: am I in the right forum for this question?

Thanks in advance,
Ortis
 

RDA.Lawns

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3 basic things to run. Fuel spark air. How good is the compression? Have good spark and good compression it may be out of time.
 

RDA.Lawns

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I never repair 2 strokes just replace them . Try to keep all my equipment 5 years still under warranty then replace. I'm sure there is several here that will help you.
 

Ortis

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3 basic things to run. Fuel spark air. How good is the compression? Have good spark and good compression it may be out of time.

Understood. I thought that maybe the flywheel slipped somehow, so I removed it again and found that it really was properly aligned. I'm not sure what compression should be on this thing, but I'll measure it. I have a new cylinder, piston, and rings. It's a bit hard to believe that there could be a compression issue. Even with low compression, I would expect to get a pop with ether.

Thanks
 

RDA.Lawns

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A quick compression test will rule it out. If its good I don't have the specs but around 90psi is my guess then its probably timing. Rivets or Bert are fairly sharp on 2strokes maybe they can help.
 

primerbulb120

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As Bert can tell you, compression tests can be misleading if your tester fills up less space than the spark plug does. You'll get an erroneous low reading.

There more things I can think of:

1. Your muffler may be clogged. See if you can get the engine to pop without the muffler.

2. You have compression, but you need crankcase vacuum as well. Otherwise the fuel will not make it to the cylinder. Is the spark plug wet after you crank it?

3. You may have a bad spark plug. Some bad plugs will spark during testing but not under compression. I would just replace the plug if you haven't already.
 
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