No spark at plug. so iam guessing coil is shot. mac 110

My bet is the points and /or condensor are shot.

Gap should be .025

All machines will have a coil or electronic module, it will be under the starter cover, either at the side of the flywheel or underneath the flywheel.

No. Your magneto or wire could be broken. I recommend contacting your local authorized service center for assistance.

You may contact the manufacturer, download manuals, check fuel/oil ratios, order parts, find your local service center, and view other resources using these links:

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I trust this information has proven beneficial.

By rotor i guess you mean the flywheel, the flywheel is on a taper on the crank and will be very tight and will require a puller to remove it, you can remove the pawls and clips which will give you four threaded holes which you can manufacture a puller using these threads, this may all be in vain as there will be no new ignition parts available for it, all the testing in the world will not help if there is no spark then the electronic unit will be shot, from memory it was a SEM unit, the later 480 had a much better quality SEM unit which would fit however this would mean replacing the flywheel as well, these components were also used on the 265rx brush cutter so may well still be available.

Spark plug gap should be: 0.020" and the fuel to oil ratio is 40:1. Be sure to use fresh fuel and a modern synthetic saw oil available at home centers, hardware stores, and saw dealers. Mix well in it's own container and be sure to shake the container thoroughly each time just before filling the tank to prevent oil starvation. Hope this helps!

Change the COIL aka spark plug cable and COIL.

Try a new coil.

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Lou

Chain saws are still two-cycle engines (gas and oil mix) and they foul the spark plug pretty rapidly if not in perfect tune. Remove the spark plug and re-attach the wire and let the plug contact any metal part such as the cylinder head. Make sure the gas petcock is off and the start switch is on. Pull on the recoil starter and see if you have a spark jumping from the center electrode of the plug to the outer electrode of the plug. Clean and re-gap the plug and try it again. If no spark, the center electrode could be broken up inside the ceramic insulator and you can't see it. Try a new plug. If still no spark, another component of the simple electrical system could be bad. If your saw has a capacitor, change that out also. Sometimes the small coil that rides very close to the magnets on the flywheel comes out of adjustment. Proper gap for that is a small piece cut from a cereal box and placed between the coil and flywheel while re-tightening the coil bolts. Do not let the coil scrape on the flywheel. If any of this has helped, please rate accordingly. Good luck.