Chainsaw Repair

The idea was right  you just didn't go far enough with it .

There have been people who welded pop up to increase the comp on clam shell saws but they were wide pop  ups ,not like the head on a rivit .A little skinny pop up won't do you a lot of good for several reason .

First up inside the combustion chamber it does nothing for the flame front except blow it out sideways .It doesn't do a thing to redirect the transfer around the intake  side of the cylinder for a better scavanging  to purge the residue  exhaust gasses .

To raise the comp you have to fill the void that would normally be air space with metal ,you just don't have enough of it .

This is a standard  pop up on a removable cylinder Stihl saw which is somewhere around 25-30 thou .It was not done to raise the comp but to improve flow over the top of the piston .I could have made it a tad wider but it works as intended


Now I hate to bust your bubble on this and I'm not trying to be a smart azz but that design of pop  up is just not going to work the way you want it to .