Spark arrester glowing red hot?

[Dan Maynard]

I think it will have a cat, which do apparently get hot.

[sandspider]

Thanks folks.

 

It does have a cat, will have a look in the muffler tomorrow and see what I can find, but probably won't take it out, just the spark arrestor. Couldn't see any sparks coming out, just hot exhaust which heated the spark arrestor up until it glows...

[sandspider]

I pulled the muffler off thinking the spark arrester would just slip out. Nope! It's welded / brazed in, and part of the exhaust gas deflector thingy so I can't even drill off the welds. Is it just a case of drilling holes in the spark arrester mesh?

[openspaceman]

17 hours ago, Dan Maynard said:

I think it will have a cat, which do apparently get hot.

I have not dealt with a saw with a catalytic converter but as you say it will get hot because the catalyst oxidizes  out any unburned hydrocarbons, which are a bigger part of a 2t exhaust. Also it will be worse if the saw id rev limited as this dumps fresh petroil out the exhaust on the limit.

[Dan Maynard]

3 hours ago, openspaceman said:

Also it will be worse if the saw id rev limited as this dumps fresh petroil out the exhaust on the limit.

That's a good point, especially if the chains a bit blunt so that it's not biting in well, saw will rev up high.

[sandspider]

I'd guess mine is rev limited, it won't rev above a certain level either in wood or out of it. Can I just drill a few holes in the spark mesh? I assumed I could take it out and put it back in if necessary, but apparently not.

Hefty cat in there too, but that I will leave alone.

[spudulike]

If the coil is limited, the saw can still run lean. I usually set up the carb and coil rev limiter to kick in at the same time so both limit the top end revs pretty much at the same time. 

[openspaceman]

34 minutes ago, spudulike said:

If the coil is limited, the saw can still run lean. I usually set up the carb and coil rev limiter to kick in at the same time so both limit the top end revs pretty much at the same time. 

Yes of course but even if that is the reason it can run up against the rev limiter when it does so it will send neat fuel out of the exhaust . If it runs lean then the exhaust will be hotter anyway.

[spudulike]

1 hour ago, sandspider said:

I'd guess mine is rev limited, it won't rev above a certain level either in wood or out of it. Can I just drill a few holes in the spark mesh? I assumed I could take it out and put it back in if necessary, but apparently not.

Hefty cat in there too, but that I will leave alone.

You can either bypass the CAT by drilling its mount plate if you can get to it or do a cut in the muffler box closest to the cylinder and Louvre it....a bit like the old MS260 used to have. Simple and effective. Don't forget the carb retune.

[bmp01]

2 hours ago, sandspider said:

I'd guess mine is rev limited, it won't rev above a certain level either in wood or out of it. Can I just drill a few holes in the spark mesh? I assumed I could take it out and put it back in if necessary, but apparently not.

Hefty cat in there too, but that I will leave alone.

It's a one way trip isn't it ? Do what ever is easiest with the tools you have.  Drill and dremel work for me when opening exhaust outlets, removing dividers or spark screens etc.

Pair of pliers and a small hook to remove thick wire ball from a chinese top handle exhaust, that wasnt catalyst wire but it wanted gone all the same.

 

 

Edited July 19, 2023 by bmp01