by bgsengine » Sat Jul 03, 2021 5:58 pm
Trick to the rope trick is, having rope that is small and flexible enough to stuff into the spark plug hole, with piston at nearly TDC on up stroke, feed rope in until no more will go in, then back off piston a tiny bit - about thickness of rope, and feed in another length of rope - usually 2-3 thicknesses of rope will not require piston to drop low enough to reveal any transfer ports, and should be plenty enough to lock things down for the worst torques.
Only time I had a problem was with a clutch that someone installed with red loctite , and it actually was enough to compress the rope (plus flex in piston/rod/crank) enough for engine to pop over past TDC.. I had to take it completely apart to the bare crank, and put the crankpin ends in a vise and heated the clutch hub with a propane torch, and even 1/2 inch air impact took quite a bit of work to finally get the clutch loose. The owner was not too happy at paying the labor time involved in a total rebuild (at least didn't require more than gaskets, seals and piston rings) but I found out he only had himself to blame as he was the one who put the loctite on the clutch. Cost him almost half the price of a new saw.
Dolmar (before Makita bought them) had a special thick phenolic plastic insert tool that was inserted through exhaust port and fit quite snugly all the way across top of piston. Newer modern saws to reduce cost and weight (as well as increase performance per CC) increasingly were using thinner and thinner pistons and rings so it is no surprise that many of them no longer recommend using any sort of piston stop that threads in to spark plug hole.
How poor are they who have not patience. What wound did ever heal, but by degrees? - Iago (Othello Act II, Scene 3)