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Muffler Mods?

Started by gfadvm, February 14, 2014, 09:49:14 PM

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gfadvm

I have an old Jonserads (510 I think) and a much newer Echo 400. They both start and run fine but it seems all the guys on this forum do some mods to the mufflers to improve performance? Is this worthwhile for my saws? If so, I'll need some guidance as I won't know where to start! Thanks.

ZeroJunk

I usually just open the existing hole. When you are dealing with a round opening it doesn't take much to double the output. Pie are square and all that. I would not go more than 80% of the exhaust port opening, that's what everybody says anyway. Retune when you do it.

gfadvm

Thanks Zero Junk, but not sure I understand "retune"?

brettl

I have an Echo 400 and the muffler on it is the most restrictive I've seen. Just the weight of it tells you how much material is inside of it, restricting exhaust flow. Do some searches and you'll find a lot of Echo 400 threads, several muffler mod threads.

Retuning is referring to the necessary carb adjustments any saw needs after a mm. Good idea to pry those plastic caps of the hi and low needles so have full adjustability of the carb. The plastic caps that come on the needles restrict adjustment to about a quarter of a turn.

gfadvm

Thanks brettl, Those plastic caps left the day I bought the saw!

brettl

Good move, Echo seems to have a reputation for sending saws out set lean. Then they compound the problem by making it hard to properly adjust the saw. The 400 also has a rep for being a really good saw. I haven't done a mm to mine but I've read that it really makes a different saw out the 400.

KiwiKen

I know nothing about muffler modification but I notice it is a common topic here and on Arborisite. I intend to learn more.

My principle experience with two stroke motors is from owning a Suzuki TS185 trail bike many years ago. One of the things I learned is that two stroke motors require back-pressure so that the gases flow on a controlled path. Take the muffler off a trail bike and you do not get more power.

As best I can recall the hot exhaust gases need to quickly expand but not be expelled until the new petrol/air mix is being drawn into the combustion chamber. The hot gases act as a baffle to block the fresh mix from escaping. This also prevents the motor from running lean which will burn holes in the piston.

Therefore it seems to me that opening up a chainsaw muffler might not be the wisest thing to do. Certainly people who are enthusiasts and build racing saws will laugh at such concerns but the fact remains, your saw is built with an enginered muffler so tread carefully.

Kiwi.
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JohnG28

Here's an older thread that I did for a Stihl 361. Not exactly the same but should give some ideas.
https://forestryforum.com/board/index.php/topic,69759.0.html
Stihl MS361, 460 & 200T, Jonsered 490, Jonsereds 90, Husky 350 & 142, Homelite XL and Super XL

gfadvm

Thanks John. That is a very informative thread. Your mod looks factory!

JohnG28

I can't stake claim to it, learned here myself, but happy to help. Part of the reason I liked this way is, as you said, it looks factory when done. Cheap too, and easy as pie with a noticeable improvement after.
Stihl MS361, 460 & 200T, Jonsered 490, Jonsereds 90, Husky 350 & 142, Homelite XL and Super XL

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