Thread: poor match between exaust port, gasket and muffler (Stihl)

I recenttly opened up the muffler on a new 066. Once I had removed the muffler I noticed a surprisingly poor matching of the exaust port, gasket and muffler. The gasket was missaligned and smaller than the port opening by about 3/32 on two sides and about a 1/16 of an inch on the top, the muffler was a bit off as well. Has any one else run ito this with Stihl or other saws?

I spent a bit of time with a file and dreml to match the gasket and muffler to the port, Im thinking I would have improved exaust flow, but wondered if the muffler restriction would nulify any gains. Not sure but I think it would only come to be a factor as the muffler opening was increased. I did open muffler up significantly.

Set the saw into some 18"-20" poplar, worked great before, works better now!

Maybe a good thing to check and correct alignment when doing a muffler mod.

Any thoughts?

Timberwolf

Sounds like a problem associated with mass production. You make a valid point, because some guys with opened mufflers have simply moved the restriction from the muffler outlet to the exhaust port. It's worth looking at. My saws dont have two piece mufflers so its difficult to measure how much of a striction there may be there

Huskyman, you could use some prussian blue smeared between your muffler and jug to indicate a mismatch. 1/4 steel rod slit down the middle with a short piece of emery cloth stuck in it makes a pretty good "burr" per se for cleaning up exhaust ports. Make it any length you want and chuck it up in your die grinder. Russ

What Joker said, but make sure you take the jug off to do it. Bits of metal and abrasive granuals are not to good for a piston/cylinder.

It is amazing how many saws come out with that misalignment...that is just another thing that we take care of when modifying these saws..you would be surprised at the other misalignments on chainsaws....

Yeah, Ben is right, I also left out a few other details that I assumed were "givens" like smear the dye on the muffler only and then carefully align it using the bolts or even studs made specially for the task to get the perfect assembled alignment, then be careful not to twist the assembly and smear the whole mess. I have found that prussian blue also works well on telephone earpieces. Russ