Mac 10 Saw will not crank


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Old 04-25-08, 04:08 PM
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Mac 10 Saw will not crank

Tried to start saw (1 cyl., 2 stroke, no comp. release, piston ported) this spring after usual (chain, chain oil, gas/oil, etc) look at and recoil starter rope would only allow a 6 to 8 in. pull with a very healthy yank. Removal of spark plug allowed engine to spin easily w/ no scrape or other noises. Removed muffler, air filter/cover and recoil starter mechanism and found the following as viewed through carb. and exhaust ports:
1. Minimal carbon in muffler.
2. No carbon in exhaust port.
3. No apparent scuffing on piston or cyl. walls.
4. Starter rope pulls freely when removed from case and retracts properly.
5. "Dog" springs on flywheel (control for rope mechanism) OK.
6. Can easily turn flywheel/crank by hand w/ no apparent scuff or other noises.
7. Inlet and transfer ports appear clean.
8. The piston moves, at least up & down.
At this point, I took the football approach-PUNT as the reassembled "creature" behaved just the same-NO SPIN w/ hard yank!

Parts may be impossible to find, but I would fix if easy. Any advice for me? If not, then off to the Stihl shop.
 
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Old 04-25-08, 06:52 PM
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did you try it assembled minus the muffler? sounds like to much back pressure.
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Old 04-26-08, 12:12 AM
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Sounds to me like there is oil in the cylinder, increasing the compression to the point that it's hard to crank. Does it crank easily with no spark plug?
 
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Old 04-26-08, 07:41 AM
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The engine cranks very easily w/ no spark plug.
 
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Old 04-26-08, 07:45 AM
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Yes, tried it w/out muffler and other stuff assembled-NO CRANK then. The muffler is not plugged, but does have a bit of crust. When pulling cord, it is like hitting a brick wall at a 6 to 8 in. pull.
 
 

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