Chainsaw Repair

In my old age, my eyesight is not what it used to be, so making a shim is easier for me than detail grinding in the cylinder because I made a jig out of a trashed (white death) pair of 372 cases. I have a very small router that I use with a spiral carbide cutter (it is used for inlay cutting in furniture making) that has a bottom bearing that will follow the case without damaging the case and cut out the shim. I have used it on copper shim stock up to 0.060 and aluminum up to 0.080.  The port timing is difficult to measure, I have thought more that once about cutting the top off a cylinder to try to make it easier to make those kinds of measurements but have never gotten around to it.

If you dont have a lathe, you guys may want to try fashioning a cylinder base cutter out of a piece of plexiglass or thin hardwood.  Something that has a flat surface.  Trace around the base of the cylinder spigot onto your flat material.  The spigot is the metal guide that sticks out of the cylinder base and fits down into the crankcase.  Cut out the hole making sure the spigot just fits and there is enough room for the ears of the cylinder.  Fix a piece of good quality sandpaper to the flat with some spray adhesive.  Cut out the sandpaper from the opposite side using a razor blade.  Fit the cylinder spigot into the hole of your flat over the paper and give it a couple twists.  It takes maybe 10 minutes to cut .015 inch off the base of your cylinder with good paper.  Check your spigot as it may also need trimmed but you can do this with a file.  You can now set your squish a little closer and still use a thin gasket.     

Post pictures and results on the 350 when it i done. Your 372 chain brake parts go out in tomorrow AM mail.

Cheers!

Roughed out the 350... no paint on the muffler, no polishing on the die grinder work. Just wanted to see if things would go together and work......they do. Will run it then go back and make things pretty if it runs WELL enough to be interesting....uploading a video of its guts and is first minute of run time. It needs a chain and air filter..... the air filter might be interesting... If it shows promise, then we can go back and tweakm& clean things up and make it right .. pretty as well. But for now... just proof of concept saw. I'll stick the video on youtube where my stuff usually resides on my afleetcommand channel  Its the "fugly Husqvarna 350...."

Test assembled the saw with no base gasket and 272 piston, runs hits cylinder top. Tried again with AM base gasket, same results. With 2 gaskets clears cylinder top but don't know by how much. 2 base gaskets are nominally 0.0343 uncompressed. So if 1 gasket is half that 0.0171 perhaps a copper shim and a single gasket. Got to take it apart and measure squish with two gaskets.

Maybe a piece of soft flashing between two thin gaskets would give you the squish your looking for?  Had you posted that you had a small router that you used on the copper shims?