modified mufflers

[chainsawchap]

looking to modify mufflers for chainsaws on my dime

looking for some advice what to do with stock mufflers I got a welder I can use but need some info on what to do to stock mufflersto make this dream a reality.

thanks chainsaw chap here

 

[Ted Jenkins]

Saw mufflers are not well engineered devices for most part. One will readily see this once taken apart. A limited amount of space to baffle hot exhaust with out blasting OP eardrums is essentially the target. Most people modifying mufflers just drill the baffling holes bigger to make more exhaust flow. When ever I have a reason to make any major rebuild and space allows I add as much volume to the devices as possible. Since I work with several agencies that would be alarmed if they heard an extra loud saw. So making even 10 or 20% more flow does make a noticeable difference. Thanks

 

[chainsawchap]

Saw mufflers are not well engineered devices for most part. One will readily see this once taken apart. A limited amount of space to baffle hot exhaust with out blasting OP eardrums is essentially the target. Most people modifying mufflers just drill the baffling holes bigger to make more exhaust flow. When ever I have a reason to make any major rebuild and space allows I add as much volume to the devices as possible. Since I work with several agencies that would be alarmed if they heard an extra loud saw. So making even 10 or 20% more flow does make a noticeable difference. Thanks

thanks ted I might not get it but if I take all the restricted junk out of the muffler some how and drill 2 holes in the outside and have ports welded in would this allow the saw to breath better more air more fuel more fire right? now with doing a muffler mod I take it you have to adjust the carb a touch to compensate for the more fuel air right? not adjusting the carb would make the saw run leaner due to more air is coming threw the engine right. what are your thoughts.

thanks ted trying to come up with a way to use old mufflers from stock saws to make performance mufflers out of.

 

[Ted Jenkins]

What would work great is a well engineered tuned exhaust. Of course the saw would then be a clumbsy piece junk. Wider longer higher deeper what ever allows for more flow through the thing. For many a spark screen needs to be added as a finale. I have found that a half an inch here or there makes a difference. Of course some one could make a completely new muffler to fit what ever space is available. For me a little welding that might allow for 25% more flow is worth the effort. If the DB level is not important just drill away. Thanks

 

[Jed1124]

thanks ted I might not get it but if I take all the restricted junk out of the muffler some how and drill 2 holes in the outside and have ports welded in would this allow the saw to breath better more air more fuel more fire right? now with doing a muffler mod I take it you have to adjust the carb a touch to compensate for the more fuel air right? not adjusting the carb would make the saw run leaner due to more air is coming threw the engine right. what are your thoughts.

thanks ted trying to come up with a way to use old mufflers from stock saws to make performance mufflers out of.

What kind of saw is it?

I like to check rpm with the stock muffler, then do the mod and check the rpm’s after. Then tune the high side to bring it back down to spec. I’ve seen saws that have increased a full 1k in rpm after a muffler mod.

Of course with an auto tune saw none of this applies.

 

[chainsawchap]

I am doing my first build from cases up on a older stihl 028av supper trying to research some good bearings don't want china garbage. I ordered a new hyway 46mm clydner from ebay It comes with gaskets fuel filter which I will use a stihl filter . I am planning on porting and polishing the cylinder and posibley getting it decked I need to find a good machine shop I think I wil ask my uncle he should no someone close.

I was considering using a grocery bag for gaskets and saving the new gaskets for templates but I might just use the gaskets.

so far my parts list consists of these parts new bearings,seals,intake boot,carb rebuild kit and a foam filter

I am very excited about my first build from the cases up hope I can get the old girl to throw a lot of slaw need a nice chain and bar also 16 or 18 not sure yet undetermined.

thank you all so fare for the help that's were this saw seems to be going.

 

[Jed1124]

Before settling on which base gasket to use just make sure you get a good squish measurement. Those aftermarket cylinders can be real tight or real loose.

 

[chainsawchap]

please explain squish mesurements in a simple form

 

[Jed1124]

please explain squish mesurements in a simple form

The amount of distance between the top of the piston and the roof of the cylinder at top dead center.
Your generally shooting for .020-.025 with a gasket delete. Stock is usually around .030 give or take. I’ve heard of aftermarket cylinders being .045 or more.
Squish is measured by fixing a bit of soldier to the top of the piston with a dab of grease then “squishing” it to the top of the combustion chamber, then measuring it with a micrometer.

 

[Ted Jenkins]

What kind of saw is it?
I like to check rpm with the stock muffler, then do the mod and check the rpm’s after. Then tune the high side to bring it back down to spec. I’ve seen saws that have increased a full 1k in rpm after a muffler mod.
Of course with an auto tune saw none of this applies.

Always check the tune after any modification that includes taking the spark plug out. When you are sure that 4 stroke condition is obtainable proceed to run it and then double check that your spark plug in not black or grey but a medium brown. Most people here discover that their saw seemed OK but did not check to see if the tuning was spot on. Thanks

 

[chainsawchap]

thanks everyone for the good advice

 

[chainsawchap]

What would work great is a well engineered tuned exhaust. Of course the saw would then be a clumbsy piece junk. Wider longer higher deeper what ever allows for more flow through the thing. For many a spark screen needs to be added as a finale. I have found that a half an inch here or there makes a difference. Of course some one could make a completely new muffler to fit what ever space is available. For me a little welding that might allow for 25% more flow is worth the effort. If the DB level is not important just drill away. Thanks

 

[chainsawchap]

Thanks for the advice I will be drilling away soon.

 

[chainsawchap]

The amount of distance between the top of the piston and the roof of the cylinder at top dead center.
Your generally shooting for .020-.025 with a gasket delete. Stock is usually around .030 give or take. I’ve heard of aftermarket cylinders being .045 or more.
Squish is measured by fixing a bit of soldier to the top of the piston with a dab of grease then “squishing” it to the top of the combustion chamber, then measuring it with a micrometer.

This makes sense thank you

 

[chainsawchap]

question on the fire screen area of the two part exhaust I would like to put dual port pipes coming out do I need to carefully remove the tac welds and eliminate that metal inside there to create more room for air to flow I would think it would breath better. I have never attempted to modify a muffler this is all new to me and I hope I don't destroy what I have. but in the life I know sometimes you got to struggle threw and make mistakes and loose money to learn. learn the hard way they say.

thanks everyone for your help so fare I am really enjoying arborist sight lots of great helpful folks on here. hope everyone had a nice Christmas 2020 is coming fast like to fast. I swear the older I get the faster time goes by this is why I ride a bike it slows down time some and I get to take it all in and get some exercise well that's besides the point back to learning more about these great saws. chainsaw chap here

 

[Ted Jenkins]

Many mufflers are a two part that is spot welded together or just held together by the mounting bolts. I often take the halves apart and weld a strip of sheet meter to make it over all a little larger. Spark arresting screen can be purchased from several sources. If there is a chance your saw will be inspected it needs to have the proper screen that can be mounted in several ways. Your imagination is the limit. Thanks

 

[chainsawchap]

Thanks hopefully some day I figure out pictures on here I would think I could do that from my cell phone I am un edjucayed that way unfortunately.

 

[chainsawchap]

well picture don't do it justice mangling apairt the fire screen and guard on the front of the muffler man germany tac welds well might need another exaust cost money to learn and smangle parts

 

[chainsawchap]

Anyone know what tool is used to weld on tin metal for these chainsaw mufflers who has been threw the struggle to learn? I am trying to design my own usa modified mufflers with old mufflers on saws theres got to be a way to do that? brasing,tig,mig not really sure not a welder?

 

[moojpg2]

Anyone know what tool is used to weld on tin metal for these chainsaw mufflers who has been threw the struggle to learn? I am trying to design my own usa modified mufflers with old mufflers on saws theres got to be a way to do that? brasing,tig,mig not really sure not a welder?

Most people MIG weld them. I would use Silicon bronze TIG brazing and stainless to make it look fancy, but I'm a welder.