Lakeside53's --361 muffler mod w/photos

[Haywire Haywood]

Yep, that's what several saw builders use, they mostly weld them on from what I've seen. The one I had didn't like the screen though, broke it off and spat it out.

Ian

 

[woodyman]

I thought I saw that $20.00 muffler outlet for the 281 on a ported muffler I was looking at for my 359 and they wanted like $100.00.The muffler was new with the added outlet but I dont know if they drilled or gutted the inside out.It was too much for me so I did my own.Will have pics as soon as I can get ahold of camera again from sister.

 

[Haywire Haywood]

If you do use that one, don't make the mistake of just hacking out the biggest square the deflector will cover. It will likely be too much unless you're installing it on a big saw. The output area of that one maxed out is twice what the Lakeside type mod has.

Ian

 

[jrslick22]

I just couldn't help myself.

Hi, first of all let me say thank you for such an informative an well kept forum (this is my first post) i have enjoyed the last few months of reading.

After reaching the end of this and a few other threads i went and brought my self my first chainsaw, i decided to get a Dolmar top handle, i enjoyed using my new pencil sharpener on meth so much i ran out an brought a used 372 XP as well, which well to say the least was a 'popcorn maker' until i did a bracket muffler mod now my mates are calling it a noodle maker!

after grinning so much due to my new found pleasure i brought a used husky 36 which i felt would have a bit more guts on the ground without overdoing my back (yes of course i have a bad back as well).

I then stopped at Bunnings (like home depot) and couldn't help but but another POS top handle to keep around as my loner, it was about $70 US and i love to "issue" it to my mates with a blunt chain - also a great source of the somewhat permanent grin i now have.

My wife is not exacly thrilled as this all sort of happened over the space of about 4 or 5 weeks - what can i say i only know one speed! i guess what im trying to say is i guess you guys ot to have some type of disclamer on the site that warns people of the potential addiction, seeing my freshly ported 372 make noodles out of pine was like witnessing the birth of my first child, i would of shed a tear if it wasn't for the stupid looking grin from ear to ear.

so yeh thanks a lot guys, my addiction will probibly end with astranged children and a devorce but thanks anyway.

now for my questions:
1. How come this thread ant a sticky? great tread four paws
2. As i know nothing about tuning two strokes i need a little help with the final touches on my 372, when i hit top end it sort of has this flattning out sound, i have played around with the H fuel adjusment including grinding off the limiters as other s have done but do not seem to be able to find what i beleive is the sweet spot. i have noticed that if i take her about a quater turn in (clock wise) she really starts to increase in revs as i understand though this is the lean side, if i take her out about a half a turn from that point she starts running ruff so i have her set a little over half way between the two points on the out or rich side (assuming anti clockwise for richer) with the idea that i am better off running to rich than to lean.

i have read the link: http://web.archive.org/web/20051018212959/www.madsens1.com/sawtune.htm
and have downloaded the workshop manual but am still not 100% sure what i am doing and would feel like my wife has file for devorce if i were to cook my 372.
please help.

thanks.

 

[Urbicide]

Hey Junior, welcome to AS. Great 1st post. Yes, 4 Paws does make some excellent tutorial threads. Does your 372XP have a limited ignition module? These make tuning more difficult and you can damage your saw if you lean it out too much. The limited modules are blue in color. It will also have the maximum RPM rating engraved on the side of the module. The unlimited modules are black in color. The black module is the one that you want. Another important tool is a tachometer so that you can accurately set the carb. Seeing numbers on the tach is safer than trusting your ears, especially if you are new at this or if your hearing ain't what it used to be.

Be sure to compensate your better half with something she really likes when ever you buy another saw. This might get to be more expensive than your saws depending on what makes her happy.

Now as far as getting the smile off of your face. Just keep a lemon in your pocket and take a bite out of it as needed.

 

[jrslick22]

Hey Junior, welcome to AS. Great 1st post. Yes, 4 Paws does make some excellent tutorial threads. Does your 372XP have a limited ignition module? These make tuning more difficult and you can damage your saw if you lean it out too much. The limited modules are blue in color. It will also have the maximum RPM rating engraved on the side of the module. The unlimited modules are black in color. The black module is the one that you want. Another important tool is a tachometer so that you can accurately set the carb. Seeing numbers on the tach is safer than trusting your ears, especially if you are new at this or if your hearing ain't what it used to be.

mine is blue, where do i get a black? would keeping the blue still be an option if tuned properly ie by the dealer, or will the black be better in the long run/better performance?

 

[Urbicide]

The blue module is usable as long as you stay below the RPM cutoff point. This is where a tachometer really comes into play. The black module is much more versatile and desirable. The module that fits the 372XP also fits over 20 other Husqvarna models. You might be able to find a used one from a donor saw. Bailey's carries an aftermarket unlimited module. It might be cheaper to order one through them with the exchange rate being what it is than it would be to procure one locally.

http://www.baileysonline.com/itemdetail.asp?item=NLM+372&catID=109

 

[jrslick22]

So i should be attempting to stick to the recommended 13500 rpm once i have the black unit, i assume the idea behind the upgrade is to make her rev more?

$42 is hard to beat, i might run it down to the husky shop to get it up and running until the ignition unit arrives.

 

[Urbicide]

The blue module obviously prevents the saw from turning over 13,500 RPM's. (The leaner the mixture the faster the saw turns.) It does not prevent you from leaning out the fuel/air mixture to the point that you damage the piston and/or the cylinder. The saw simply will not spin faster than the cut out point built into the module, regardless of how lean the "H" screw is turned. Some folks adjust their carbs so that the saw is running approximately 200 RPM's below the cut-off point. That way you know that you are safe. The black coil will not mask an improperly adjusted carb. You lean out a saw with a black module and it will scream. A tach is a handy tool to have and it is even more critical to use one when setting up a saw with a limited ignition module.

 

[Nailsbeats]

My dual port cover (pn 1122 140 0800) came in at my Stihl dealer but not my gasket so I had to use high temp RTV sealer for now to get my saw running to cut all these trees the storm has blown down. I'll go back and put the gasket in there when I get it.

I tuned the carb to the new exhaust and cut some wood. WOW, this saw gives me a virtual adrenaline overdose.

That's some sweet work man. I just finnished my second 660's muffler mod. I just open the side vent all the way to that slit and leave the stock front muffler cover on. I also chop the front of that cage off, I should plasma them totally off like you did. Longterm, I probably will. Again, nice job, looks really nice. Really makes em' cut don't it.

 

[jrslick22]

The blue module obviously prevents the saw from turning over 13,500 RPM's. (The leaner the mixture the faster the saw turns.) It does not prevent you from leaning out the fuel/air mixture to the point that you damage the piston and/or the cylinder. The saw simply will not spin faster than the cut out point built into the module, regardless of how lean the "H" screw is turned. Some folks adjust their carbs so that the saw is running approximately 200 RPM's below the cut-off point. That way you know that you are safe. The black coil will not mask an improperly adjusted carb. You lean out a saw with a black module and it will scream. A tach is a handy tool to have and it is even more critical to use one when setting up a saw with a limited ignition module.

Thanks so much for taking the time to explain you have really helped.

I will order a couple of the black units and a tacho, this way i am able to look after my own equipment without bending over for the husky dealer.

According to the info i have gathered thus far putting a whole in the muff will allow the carb to push more air thus requiring more fuel or a richer mix, but the leaner the mix the higher the revs (must be a 2stroke thing). As you have explained (and if i understand correctly) the idea is to be running higher revs with a richer mix by getting rid of the 13500 ign limiter.

So if ive got this correct:
1. Order parts 2. Fit parts 3. Attach tacho 4. Adjust fuel air mix until desired tech reading 5. Fit 32" bar and chain 6. Spray mates with noodles and popcorn while yelling thats a cute saw you've got there, your wife must really like it!

Or does the new ign unit have adjustments for limiting the revs?
What would the desired rev count be for a 372?

Thank you very much.

 

[jrslick22]

Anyone else following this tread see also

tuning you saw:
http://www.arboristsite.com/showthread.php?t=73107&page=2&highlight=muff+mod[/url]
http://www.arboristsite.com/showthread.php?t=46721&highlight=muff+mod

more on RPM
http://www.arboristsite.com/showthread.php?t=64963&highlight=muff+mod

For more answers to the same sort of questions.

 

[lectrocrew]

That's some sweet work man. I just finnished my second 660's muffler mod. I just open the side vent all the way to that slit and leave the stock front muffler cover on. I also chop the front of that cage off, I should plasma them totally off like you did. Longterm, I probably will. Again, nice job, looks really nice. Really makes em' cut don't it.

Thanks Nailsbeats.
Note that I only used the plasma cutter to separate the cage into sections that would enable those sections to flex on the factory spot welds. Then the sections came loose from the factory spot welds with very little effort and absolutely no metal damage to the muffler housing. The Plasma arc will blow a hole in the muffler housing very easily if it gets close to it. Don't try to cut the spot welds that are holding the cage to the housing.
Also, if you do completely remove the cage, this will leave only the thin metal that the housing is made of to support the entire muffler assembly where it bolts to the cylinder. This would be a weak point and over time will likely break due to vibration, metal fatigue ect. That's why I welded the stainless plate in place of the cage - for support. Are you planning to weld in a support plate also on your project?

 

[Nailsbeats]

Thanks Nailsbeats.
Note that I only used the plasma cutter to separate the cage into sections that would enable those sections to flex on the factory spot welds. Then the sections came loose from the factory spot welds with very little effort and absolutely no metal damage to the muffler housing. The Plasma arc will blow a hole in the muffler housing very easily if it gets close to it. Don't try to cut the spot welds that are holding the cage to the housing.
Also, if you do completely remove the cage, this will leave only the thin metal that the housing is made of to support the entire muffler assembly where it bolts to the cylinder. This would be a weak point and over time will likely break due to vibration, metal fatigue ect. That's why I welded the stainless plate in place of the cage - for support. Are you planning to weld in a support plate also on your project?

I think other Stihls are just like that with no cage and no support there. I could certainly TIG one in there, it can't hurt. When I cut the front of my cage off I actually cut the whole plane of that surface off, so you are left with two sides, a bottom, and the divider. I may be able to snap it all off the way it sits. I thought about that when I was doing it, but I wasn't by the tig and didn't want to find out I needed the support, so I left it. I don't suspect it is impeding flow much.

 

[lectrocrew]

didn't want to find out I needed the support, so I left it. I don't suspect it is impeding flow much.

Looking back, I think my first mod of just cutting the front out of that cage and also opening up the outlet supplied plenty of flow, and I do not believe completely removing the cage gave the saw any more power. Sure, with the cage removed there's no doubt about minimal exhaust restriction, but I think there's plenty of flow for the stock 660 with the cage in place. The main restriction that causes power loss is the small final exhaust output opening. In my opinion, with that area opened up, you should see all the power increase your going to see with a muffler mod on a stock saw. At the time I modded that muffler, I had plans to eventually do some extensive mods to the motor.

 

[Nailsbeats]

I concur doctor.

 

[Tzed250]

This should help...

 

[funky sawman]

Some guys state that the exhaust port should be 80% of the surface area on the cylinder head port. The question is what should it be with the increased back pressure of a spark arrestor screen?

 

[Musclenut]

All this muffler mod talk is making want to tinker with my 028. Before I start should I cut out the internal cage baffle or just drill bigger holes in it?

Also it seems some you like to take out the mesh screens and some of you strive to keep them. What's the best approch with the screens?

 

[Net-Knight1]

The muffler just came out of the oven from being coated with exhaust paint:

Nice work!!!! Looks awesome!



:jawdrop: