We have a Johny 2159 that was ported by I believe T4driller, it has been an awesome saw and has been ran a lot the last 3-4 years in our tree business. A couple weeks ago I was running it and all the sudden it started making a funny sound/not running right, and died. I could not re start it. Next day I was able to start it and it ran, still sounding funny, for maybe 15seconds then died and could not restart. Took it to our local saw shop. Stopped in there Monday and they had it all apart. Said everything looks fine, it has compression, fuel system is working fine, piston looks great, but can't get any spark. They pulled the flywheel, which he said was nice and snug and had to be kind of pried off. But the key is either worn out toward the tip or has been modified. He knows the saw is ported. He said he's wondering if the porter modified that key to change the timing?? If that is the case he wants to try a coil and see if that does it. If the key is worn and not modified, he's thinking maybe need a new flywheel. I have always seen in the ported saw adds "advanced the timing", but never knew exactly what that meant. Any thoughts on this would be much appreciated, as we really love the saw, I'd put it up against a stock 70cc saw any time. Thanks for any knowledge in advance! I haven't posted much on here, but I read almost daily.