How do you modify a muffler?

[Mongo]

I have a Makita dcs 6401. A couple of them actually. I hear all this talk about modifying mufflers and couldn't find much info on how to do one. I know that all saws are not the same so I was wondering if there is anyone who has done one on a 6401 or dolmar 6400. The 6401 is an exceptional saw for my standards but I would like to tinker with one of them and see what the difference in the two would be. I also read something about trimming the carb. I have no idea what "trimming" means. Is that a requirement with modifying a muffler? I would like to avoid messing with the carburetor, except for adjusting it, if at all possible. I'm pretty handy with tools and mechanic work but I have never fooled around with a muffler on a chainsaw. I would be grateful for any advice! Oh, and there's one other thing. What is the highest compression anyone has seen on a chainsaw? Mine check out at 170 and 165. Is that about average?

 

[computeruser]

There are a number of posts on Rich Hoffman's work on Dolmar/Makita mufflers. Search for 'em - lots of good pics and discussion.

 

[timberwolf]

Use the advanced search 77 threads on muffler mods. It's a case of making the outlet hole bigger on the muffler and reducing or eliminating any restrictions from the exhaust to the outlet.

I have not seen the insides of the muffle for that saw, so can't say exactly what you need to do. Go through the threads, you will get the idea, many pictures of different mods on differnt saws.

170psi on that saw sound normal, I have seen up close to 300 psi, but not stock.

 

[Mongo]

Thanks!

Thanks for the reply! I'll go check it out.

 

[rahtreelimbs]

Here is what you can do to a Makita 6401 muffler!

 

[Mongo]

Cool!

Here is what you can do to a Makita 6401 muffler!

That looks like it would be a lot easier than undoing the folded seem to get to the inside. Plus, it gives it character. You might would even want to name it and give it a nice cozy spot next to the recliner after that. Did you do anything to the inside like break the baffle off of the silencer looking gizmo coming off of the exhaust port hole? If that's proprietary information you don't have to tell me. I saw where someone had drilled out the holes a couple of sizes larger and only a little off of the baffle. Thanks for the pics! I like that!

 

[rahtreelimbs]

That looks like it would be a lot easier than undoing the folded seem to get to the inside. Plus, it gives it character. You might would even want to name it and give it a nice cozy spot next to the recliner after that. Did you do anything to the inside like break the baffle off of the silencer looking gizmo coming off of the exhaust port hole? If that's proprietary information you don't have to tell me. I saw where someone had drilled out the holes a couple of sizes larger and only a little off of the baffle. Thanks for the pics! I like that!

First off, the credit for the pics goes to Computeruser. Nothing proprietary here. On this muffler the original port is opened more. The basket inside is relieved of the front portion. With the added port in front the exhaust has a straight shot out!

 

[computeruser]

I also read something about trimming the carb. I have no idea what "trimming" means. Is that a requirement with modifying a muffler? I would like to avoid messing with the carburetor, except for adjusting it, if at all possible.

All that you will have to do is nibble away at the "wings" on the H adjuster screw that limit the degree to which the H circuit can be richened up for emissions reasons. Once the muffler is opened up more, the saw breathes better on both the intake and exhaust side, and will be relatively leaner than with a choked-down muffler, so you need to richen the mix up accordingly. I nibbled away at the wings with some small diagaonal cutters and a Dremel and the whole process took maybe 25 minutes with the crappy Chinese cordless Dremel rip-off that I was able to borrow.

 

[Mongo]

Good information!

I really appreciate the information that I have received from everyone! This is a great site to learn from the pros information that you wanted to know but couldn't because you didn't know where to look. It really helps to know what works and what doesn't. Thanks! I'm addicted!

 

[bugler]

I like Windsor bars also. Good pics.

 

[pbtree]

I really appreciate the information that I have received from everyone! This is a great site to learn from the pros information that you wanted to know but couldn't because you didn't know where to look. It really helps to know what works and what doesn't. Thanks! I'm addicted!

Mongo,

Welcome to the site, and yes there is tons to learn here... As to the addiction, I feel your pain