More Muffler Mods Out Of Shear Winter Boredom

[rahtreelimbs]

Winter has me real bored right now. I decided to dig into some muffler mods. Here is a Shindaiwa 357 climbing saw that I picked up for a real good price. These mods made a real difference in the saw's thottle response. This muffler has the typical baffle/basket inside. I opened up the top and bottom eliminating any holes. Then I opened up the outside hole just about as big as the pipe. I mig welded the pipe on. I know the saw is heavy, but it makes a good backup to the 020T.

 

[rahtreelimbs]

Other side.

 

[rahtreelimbs]

Finished pic. As you can see the pipe exits real nice thru the side cover.

 

[rahtreelimbs]

Makita 7301. This one was a little harder. No room to really work inside. Thanks to a flashlight and the Dremel with a real small burr tool, I was able to open the top of the basket up to about 1" X 1 1/4" square. If you look close at the stock outlet hole I opened it up to roughly the same size as the deflector. The stock hole was about 1/2" round. I used the same self-threading tool that held the original screen. I used the original screen as a template and installed a bigger one.

 

[SilverBlue]

Nice work Ritch, looking for work? when can you start?
I have some mufflers that will be milled out of billet aluminum for my stihils, they will be trick! The only problem is getting time on the milling machine.

 

[rahtreelimbs]

This is Dan Henry's handiwork on my Dolmar PP7900!

 

[Toneman]

Nice work!

 

[eric_271]

Rich I have a makita 520i. If I cut the baffle out and open the out let hole a little is there any chance of hurting the saw's performance?

 

[rahtreelimbs]

Originally posted by eric_271
Rich I have a makita 520i. If I cut the baffle out and open the out let hole a little is there any chance of hurting the saw's performance?

IMO, no. There is alot of info on this site regarding muffler mods. The current opinion on this site is that most of the latest mufflers leave alot to be desired. Far too much backpressure. By opening up the muffler you can increase performance and the saw will run cooler. Just make sure not to go too big on the size of the outlet hole, too big can hurt performance. Also, make sure that you deburr anything that you cut or grind. Make sure to give the muffler a real good cleaning when you are done. You can install a screen, I do, but it is not necessary.

 

[rahtreelimbs]

Originally posted by RockyJSquirrel
Good answer, Rich. I'd say that pretty much any modern saw will benefit from muffler work. But as with any mechanical project, a person can damage a saw if they screw something up. Don't get metal shavings or carbon chunks into the cylinder and make sure you properly set the carb after modifying the muffler. With the better flow comes a need for more fuel. If you do not adjust the carb there is a good chance your saw might be running lean after the muffler mods.
pro carb adjustment
Here's a neat image someone shared here a while back.
two stroke animation

Thanx Brian,
I was going to mention the carb adjustment issue. Too many things going on here tonight. Thanx for the catch!

 

[shoot501]

eric_271; The Makita muffler [ if like the Dolmar ] is crimped together, not to easy to work on. The inside baffels are not all that restrictive so if you could enlarge the outlet or add another 5/8" outlet I think it should be OK. The 520i is no slouch the way it is.

 

[Kneejerk Bombas]

Those crimped together mufflers don't scare me one bit. I've taken them apart, drilled them out, and reassembled them on the tailgate of the truck in about 15 minutes. Just use a screw driver to unpeel the fold and pry them apart. When you're done, just crimp it back together.

You need an adjustable high speed jet (and know how to set it) to open a muffler.

 

[eric_271]

Thanks for all the information includeing carb adjustments. Im sure the muffler is the same is the Dolmar. Everthing has made in germany and specs all match 115i dolmar. look out muffler here I come. Thanks again All

 

[hokiebob1]

Since I'm a novice, I love reading from such knowledgable folks. Why do you have to disassemble the muffler at all - can't you simply remove it, drill and weld nipples/deflectors as needed, then reinstall? Also, about the retuning. Do most of you do it by ear (ie. listening until it begins 4 stroking) or do you use a tach? I messed with my Husky 353 this weekend and found it interesting. Both of the carb adjusters were set to the full counter clockwise position (ie. rich) using the adjuster limiters. I tried leaning it out and then richening it up and it seemed to 4 stroke before I got it back to the factory setting, yet it didn't have the power until I reset it--is this normal-the saw is probably close to broken in. When a saw is broken in, do you typically have to richen or lean the carb? In an earlier post, I was told to cut the carb limiters off - will the needle valve adjusters vibrate after the adjuster ears are removed?

thanks
bob

 

[rahtreelimbs]

Originally posted by hokiebob1
Since I'm a novice, I love reading from such knowledgable folks. Why do you have to disassemble the muffler at all - can't you simply remove it, drill and weld nipples/deflectors as needed, then reinstall? thanks
bob

You don't have to disassemble the muffler. I won't take them apart unless absolutely necessary. I ground off the welds on the muffler on my Solo 694 to separate it. Although it was well worth it, I would try a different way. A Dremel tool with a small cutoff wheel or a small burr bit really works good. A small oxy-acetylene torch works real good if you can get in there.

 

[hokiebob1]

Thanks Rich. I presume the idea of opening them up is to remove any baffles that are in there? Hey, about other things in my earlier post - any comments on mixture setting and the movement of mixture screws if you remove the limiter tabs?

thanks
bob

 

[rahtreelimbs]

As far as mixture, read this:

http://www.madsens1.com/sawtune.htm


The limiter caps I would put back on. Just lose the tabs that keep them from turning 360 degrees!


One other thing, you may want to rethink the muffler mod if your carb has no HI adj. I may be wrong on this, but I think you would want to have the ability to adjust the HI screw.

 

[lucky]

If you take of the limiter tabs would the screws be able to back out on their own. On a stihl, it looks as though those dam tabs serve to kinda hold things in place. I could be wrong though.
has anybody removed them and survived? Lucky

 

[hokiebob1]

Lucky-thats kinda my question. The only reason I ask is because when I inspected mine, it was fully seated in the rich position, which I thought was unusual-did they set it there, or did it vibrate there?? As for my saw, it does have the hi mix adjust, so the muffler mod should be ok, though I'll have to either remove the limiter caps than reinstall, or cut the tabs off (which I'm leary of if they'll vibrate one way or the other).

 

[rbtree]

Yes, leave the limiter caps on, just grind the tabs. The screws can vibrate out of adjustment, unlike older carbs that never did. It kept happening to an 036 I had that the shop had taken off without me asking..I had them put back on. Not a good thing especially if you don't notice the saw overrevving. Lean seizure can happen mighty quick.