my 290 muffler mod pics/ what rpm should i shoot for when i tune?

[jtracy1223]

Here are the pics of the muffler mod I did on my stihl 290 tonight. I went with a 1/2" hole right threw the center of the indent and then cut off a good size chunck of the outter deflector. I would say the opening of the deflector is 3-4 times bigger than when I started. I took it back all the way to where the angle ends. I did not put any extra holes other than the one big one nor did I open up those tiny lil slots its expected to breath out of. If it would help more I still can but I think the big hole right in the center should do it? Correct me if I'm wrong. This is my first time doing this and I didn't even know it was an opption tell I found this site. I plan to pull the limiters and tune it tomarrow. I just got my works connecting tachometer today so I feel a bit safer having that to double check my ear tune work. I don't hear very well as it is and I think the problem will only get worse after I run this beast for a but. What kind of rpm range should I be shooting for on my tach?View attachment 301310View attachment 301311

 

[moody]

Never tune with a tach. Tune until it 4 strokes at wot no load and cleans up under load. Tuning by tach will get you caught up in rpm' s and a screaming saw. That's a good way of ending your saws life.

 

[bucknfeller]

Never tune with a tach. Tune until it 4 strokes at wot no load and cleans up under load. Tuning by tach will get you caught up in rpm' s and a screaming saw. That's a good way of ending your saws life.

Yep, you beat me to it...again

Tune it where it 4 strokes, and then stick the tach on it if you want to see where you're at.

 

[Saw Dr.]

Looks loud to me

 

[jtracy1223]

Ya wasn't planning to use the tach to tune. I just want to have it to know I'm not going past that point of burning up the saw because I haven't tuned 100's of saws by ear like some folks here. I don't really know what 4 stroking should sound like and the sound clip was not all that helpful. When I run my saw now as it was set by the factory I don't hear any 4 stroking or at least don't think I do??? It is running right abou 12,500 at full rev today before the muffler mod should I be hearing it 4 stroke at this point? I have read for hours about tuning carb by ear but it seems like one of those things you need to do a lot before you get it just right. That's why I got a tach with the hope that if given a number that I should not cross I would save myself from burning up a expensive tool that I can't afford to replace.

 

[Stihlofadeal64]

For a reference number tune it to 12,000. By the looks of the muffler can we say the saw is practically new? I'd let it break in with your muffler mod for a bit at 12,000 (personally). Then after several tanks you can bump it up to 12,500 (that's the recommended Stihl setting for WOT no load). If you're having trouble with your hearing already -- buy some ear muffs hearing protection or wear plugs. This thing looks like its going to be LOUD. Happy Sawing.

 

[cedar hacker]

Lol.hearing protection should be a must.i didn't think mine was to bad till i got home and my wife was hoaring at me and all i hear is the saw still going. Not a bad thing but she thought so.so now ear muffs. I set mine around the 12000 mark to play it safe

 

[Moparmyway]

You could set it with a tach .......... to 12,000, but would you be on the rich side, or the lean side ?

OR

You could set it real rich on the high side, then start cutting and slowly lean it out untill it cleans up in the cut.
No fuss, no messin around, put a tach on it after you have got it running clean in the cut.
No way that you will miss tuning it this way, even if your hearing is off. I am deaf in one ear and I can feel it as well as hear it when she cleans up.
Dont try leaning it out WOT no load, thats a recipe for a burned saw.

Start rich, start cutting and lean it out as you cut (stop if you want and turn the screw just a little each time) untill she stays nice and crisp without blurbering.
Use a freshly sharpened chain !!

 

[Stihlofadeal64]

You know after reading that I can see how it would be difficult if your hearing is impaired. As I get older it gets more difficult. Having worked around loud machinery for years, shooting guns with no hearing protection and the process of getting older my hearing is not what it was.
I can see how your process has worked for you. And I must thank God that I still have a measure of my hearing, it is very important when tuning your saw. I tune both ways actually -- by ear and tach. Thanks for the post!

 

[jtracy1223]

Thanks for the help everyone. I fired her up today and after a lil smoke (I started rich on both high and lol with high out 2 turns and low out 1 and a half) i started to get it. I think I was getting it 4 stroking but I still am unsure. I left it at about 3000 rpm at idle and low 12000 for high I think about 12,100 or 12,200. Want to get it in some wood and see how it does.

 

[Treeman2113]

Direction

Can you give me specific directions on doing this mod ? Thank you

 

[jtracy1223]

Remove the muffler by removing the 3, 5/16" bolts that hold it on. There will be a front part that directs the exhast a screen and the main body of the muffler. What I did was drill a 1/2" hole in the indentation in the middle of the muffle so that the exhast could vent strait out and then removed a chunck of the front deflector so the larger hole had more roon to vent out. I know that's not a grate "specific direction" but I'm not very good at teaching. If you use the search at the top of the page and search for "290 muffler mod" and there is is a few good threads on how to do this mod and they explain much better than me. Just be sure after you are done that you remove the restrictor caps on your carb (also search for how to do this its not hard but I needed to read up on it before I could get them off) and then tune you saw so the high side is set ritcher than factory setting or you will burn your piston and cylinder up quick from. What I understand. Now take in mind that I am new to this and I am just repeating what I have learned from the people on here that are much smarter about saws than myself. Good luck and use the search and it will probably tell you anything u need to know but don't be afraid to ask if u don't understand or just want to get a new oppinion on an old question.

Can you give me specific directions on doing this mod ? Thank you

 

[Stihlofadeal64]

Thanks for the help everyone. I fired her up today and after a lil smoke (I started rich on both high and lol with high out 2 turns and low out 1 and a half) i started to get it. I think I was getting it 4 stroking but I still am unsure. I left it at about 3000 rpm at idle and low 12000 for high I think about 12,100 or 12,200. Want to get it in some wood and see how it does.

Keep us posted. With the muffler mod you should experience some more pizzazz in the cut. Let us know what you think about the whole thing - sound, strength, throttle response etc.

 

[blsnelling]

Thanks for the help everyone. I fired her up today and after a lil smoke (I started rich on both high and lol with high out 2 turns and low out 1 and a half) i started to get it. I think I was getting it 4 stroking but I still am unsure. I left it at about 3000 rpm at idle and low 12000 for high I think about 12,100 or 12,200. Want to get it in some wood and see how it does.

1 1/4 should have been more than enough on both needles. It probably hardly ran at 2.