Ms 260 muffler mod template
- Thread starter Vintage Engine Repairs
- Start date
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The screen is the first thing we toss here as its not needed but your exit hole is now much larger than stock so a screen is not going to restrict your stock cylinder from exhaling well. There is a few more tricks I use on the highly ported saw mufflers but for a stock motor yours will flow more than the engine can put out.
Thanks mate
I’m not sure how likly it is to happen, but with bush fires spanning the whole of Australia right now that have killed so many it would be incredibly irresponsible to use a saw with out, even just for the principle of the fact! I always carry a fire extinguisher in the car too as I have heard some scare stories!
Been watching the fires on the news net, Aus is so dry and we are so wet most of the year, very different conditions.
billyboy
ArboristSite Operative
From what I have read in searches, it seems like muffler mods should be around 80% of exhaust port in cylinder. Doesn’t going over that 80%figure start to mess with back pressure with less than desirable effects? Would you mind elaborating on that? Thanks,
For one, you can forget the back pressure foolishness, timed cuts with a certain model saw is how I reach what I do with any modified part of a saw. Where most operators will run a screen on their saws that creates a choke down of any muffler exit so a 3/4 hole becomes more like a 5/8" hole, add carbon and choked even more. I reached the size of exit hole and its placement by destroying a half dozen OEM mufflers that I can weld back up if I wanted to but don`t need them currently. The size and placement gave me the best gains and sound abatement, works for me. A two stroke will run fine with no back pressure at all, many of the real old two strokes had no mufflers at all.
Yes it’s crazy isn’t it! Couldn’t agree more. From what I have heard it seems like it’s the exhaust gas heat that creates the fires that most have experienced? Is this true?
SteveSr
Addicted to ArboristSite
Usually it is a piece of red hot carbon that breaks of from somewhere in the combustion chamber. The screen keeps it from escaping the saw and starting a fire.
I can’t understand why someone would do it knowing the destruction. The punishment must be incredibly lenient!
Could be heat or could be red hot carbon bits, the only fire I seen started from a saw was one where the front exit muffler was actually resting on the doughty, soft, punky log and the heat from the exhaust caught the moss on the bark on fire. The exhaust is very hot and if it exits directly against very dry material then it can start a fire. Our woods here may get a bit dry for a month or so each year but that is when the least saw cutting is done, if its hot we wait a bit til the rain comes and the air temps fall back below 70F.
Starting fires intentionally, oh my, that would be grounds for murder.
If you run a twoncycle at.night you can see sparks coming out the exhaust on occasion.
Adding bigger mesh defeats the purpose of a spark screen. Either use the proper mesh or if your climate allows ditch the screen.
Adding bigger mesh defeats the purpose of a spark screen. Either use the proper mesh or if your climate allows ditch the screen.
