Is the curve for advance and such on the 51 coil different than 262? Long term may be worth going with 262 coil
One of the 3 262's Dan did last year had the flywheel key sheer and shift. I was running it and it started running like crap (triggering would not accelerate -- just bogg).
When trying to restart it kicked back and bit Dan pretty well w/ off timing going on.
Took to the bench and pulled flywheel to reveal sheered key.
Dan used valve lapping compound on the crank to get the surface prepped to grab the taper on the flywheel well.
Lined up the key slot and original key location on flywheel to get it in the right spot and tightened down well so taper grabs the flywheel.
Saw was returned to it's original beast performance and ran a couple of tanks through it and gave it to it's new owner.
+1 on changing the stop switch -- I had similar problems w/ my 1991 262 tore my arm out trying to get it to run after a carb rebuild, cylinder cleanup, and new piston installed.
Disconnected the spade lug at the switch and saw came to life ran perfect. Touched spade to case to shut the saw off until I got a new switch from a local dealer that to my surprise stocked 262 switches.
Certainly let us know how this all turns out!
Videos from my stop switch debugging -- called Dan that day and he and I were thinking coil. I had an extra coil to try but turns out my original coil was fine once switch figured out. This 262 is once again ripping well -- still needs some tanks through since new piston but it's gotten quite strong again. Carb rebuild success and got the tune all dialed in... was playing with this saw at Dan's GTG a few weeks back. Need to cut some firewood with it now.