Mac 15 - won't start

[Edmccabe]

I friend recently asked me to get a MAc 15 which has had very little use - but has been sitting for over 20 years with no use - running. The saw was stuck - but I was able to get it freed up with solvent and have sanded & set the points, cleaned the carburetor and replaced the fuel line. I have very good spark to the plug and fuel delivery but no ignition - even with gas or ether sprayed into the carb - not a single fire.

The compression is only 100psi -which may the problem - though I have started saws with less compression when cold.

I have used Bon Ami in the past to reseat rings & clean up the bore - but only introduced in small quantity into the air stream through the carb with the engine running.

Any ideas short of a tear down would be appreciated.

This saw is 80CC with an 18" bar and is in new cosmetic condition - to nice to scrap.

Ed

 

[pioneerguy600]

I have rebuilt and own a few of the Mac 15`s and they are very hard to get started once comp falls to 100 psi , if you remove the recoil cover and hook up an electric drill to a socket then put it on the flywheel nut and turn it over with the drill on half speed . It will usually fire up and run but you could also induce some bon ami into the airstream through the carb and let that do its work. My guess is the rings may still be stuck in the piston lands.
Pioneerguy600

 

[Edmccabe]

Mac 15

Thank you Jerry - I suspected that this was the problem. The crankshaft nut loosens in operational rotation but I can spin it with my 1/4" impact wrench on the flywheel puller.

Ed

 

[pioneerguy600]

Ok ,if you can get it to turn over fast enough it should start up and maybe work the rings til they free up. Otherwise its not too big a job to pull it apart and free/clean everything up inside.
Pioneerguy600