Stihl MS180C-B

[KE4AVB]

Well I finally had a bad experience using a piston stop. I punch a hole the piston trying to remove the clutch. It was on so tight thought I broke the rod when it finally gave way.

[bgsengine]

Thats why I quit using them, I use starter rope instead. more surface area over top of piston to spread the force

[Arkie]

What type of piston stop were you using on the chainsaw?

Reason I ask is I use rope, but little skeptical if using rope through a removed muffler port on a chainsaw due to cocking the piston sideways. I remove the spark plug for the rope and have the piston up somewhat so as the rope does not go out the exhaust port.

I'm also careful on small engines not to bend a valve when using rope. (use minimum of rope and usually on the compression stroke so as valves are closed.

[RoyM]

You really don't want to get the rope caught in a port. You really don't!!

[KE4AVB]

Personally I just chalk it up to **it happens. Once in 12+ yrs is not all that bad.

And yes Roy I tried the rope years ago had it to to shear off in the transfer ports and one engine no matter how much rope I packed in (of I didn't fill the cylinder) it would not stop the piston. That why I brought the metal piston stops. Even the plastic ones didn't work for me, all I did was to mash them flat.

[creia]

I have always used the "starter rope in the bore" trick to remove (and tighten/torque) the starter clutches on the old Briggs I work on so that I can remove the flywheel. I have not had any problems- yet.
Michael

[KE4AVB]

I have always used the "starter rope in the bore" trick to remove (and tighten/torque) the starter clutches on the old Briggs I work on so that I can remove the flywheel. I have not had any problems- yet.
Michael

That fine and dandy on the old L-heads and even the OHV engine when you disable the valve train. THe problem Roy refers is on the two-cycle engine where there is transfer ports in the sides of the cylinder for the rope to get caught on and then shear off into the lower crankcase.

[bgsengine]

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.

[KE4AVB]

Boy I learn my lesson on Red Loctite. Don't use the accelerator unless you are very quick. Cat pump taught me that screwed the valve caps on and then pickup torque wrench I got two done but the third lock down half. It was hell to goe back out without melting the check valves.

Any way someone did put the clutch on extra tight. I waiting the intake and exhaust gaskets. No crankcase to cylinder gasket so I have to do a gasket delete install.