Chainsaw Modifications

I have a husky 372xp 28" bar and got my muffler done by walkers saw shop. The cost was only $30 which give's an extra 1/2 hp and the engine runs way cooler less heat to the engine!

Interesting. What exactly did they do to the muffler?

You may want to check out the arborist site. There's a section on saw mods there.


http://www.arboristsite.com/index.php

......or find the hardcore saw people here -
http://www.chainsawperformance.com/forumdisplay.php?f=3

I have a 361 that's ported by Ed Herd, along with a Dolmar 7900 he did and a Husky 2100 he did. I am going to have my Dolmar 5100 done by him as well. I have done a few muffler mods and they do give measureable improvements. Ed can be found on chainsawperformanc.com My 79cc Dolmar 7900 will outcut a 92cc Stihl 066 any day of the week, the 100cc Husky is a pure animal that is absolutely UNSTOPABLE with a 28" bar on it.

sedanman said:

I have a 361 that's ported by Ed Herd, along with a Dolmar 7900 he did and a Husky 2100 he did. I am going to have my Dolmar 5100 done by him as well. I have done a few muffler mods and they do give measureable improvements. Ed can be found on chainsawperformanc.com My 79cc Dolmar 7900 will outcut a 92cc Stihl 066 any day of the week, the 100cc Husky is a pure animal that is absolutely UNSTOPABLE with a 28" bar on it.

Click to expand...

Have you had the 7900 apart post-EHP? Did he get this gain with or without finger/boost ports?




To answer the original post, simply opening the muffler up on a modern saw will yield nice gains in power, acceleration, and in reducing engine temps. Those with cat converter mufflers are well advised to ditch the cat muffler for a non-cat and mod that one. The only saws I have in stock form are my Husqvarna 238 and 154, everything else has been muffler modded.

After taking the advice of posts above, I went to those sites and looked up muffler mods and from what I gather from many, many threads state that 85% is the rule of thumb. Keep the exhaust port opening 15% of total size of muffler. On my old 028 Super, I just used an 1/8'' drill bit and drilled a series of holes in the front of the muffler in the shape of a circle, about the diameter of a nickel. I do not have a welder, or know a friend that has one ready so that is the way I went with it. After I tested it out, there was a noticeable difference in the way it ran; way faster and obviously louder. I will have to adjust the jets, as I did notice that the 4 cycling that I had before is gone, and I do not want to lock up is saw. Most pictures of mods I seen have a piece of pipe about 1/2" welded either into the front, or side of the muffler. Some looked hillbilly, others looked factory. I seen enough improvement, that I will adjust the muffler on my 455. That saw runs allot hotter that the 028's I have, so hopefully this will help out, and get some more performance out of it.

Don't forget to match the opening in the muffler to the gasket