Dealer told me that my muffler mod was worthless

[Zackman1801]

The euro version of the MS390 has a higher listed HP... and a different muffler part number...

But I could see where modding your muffler would void your warranty.

Yeah cause the EPA over here chokes the things out. Pretty soon were going to have saws that run on flowers and spit out purified air.

 

[demographic]

Demo, any 2 stroke motorcycle from the last 40 years comes with a better tuned exhaust than the flat can on a saw. Instead of altering the timing/strength of a reflected pressure wave in an expansion chamber, the saw muffler is just a can with much smaller exit than entrance. If you open the outlet on that can, it flows better.

Some guys have done before/after timed cuts in the same log and posted them on youtube, bsnelling especially. I think one time Brad posted stock, ported, and then ported with muffler mod vids for a saw (G3800AVS?).

Thanks for the reply, I had figured that the expansion chamber of a modern motocrosser (and quite possibly old 1990 models like mine are) would be more advanced but the rest I just didn't know, making the timed cuts makes sense.

As horsepower is a function of torque multiplied by revs then divided by 5252 (If my memory serves me right) to increase the power of the saw it either has to rev higher or produce more torque in order to produce more horsepower.

Do the saws rev higher after the muffler mods or produce more torque, or maybe even both?

I don't have the foggiest notion about saw tuning so am pretty much in the dark.

Regards Scott.

 

[barneyrb]

The other day my dealer put a running 090 (piped with a yz carb) in my hands. If he only knew me better he might have thought twice.

 

[demographic]

The other day my dealer put a running 090 (piped with a yz carb) in my hands. If he only knew me better he might have thought twice.

YZ as in YZ Yamaha?

And what do you mean by "Piped"?
Does that mean putting a motorcycle spannie on it?

 

[Paul001]

First off...Great site, I wish I had found this site before I bought my last saw

About two months ago my saw and an oak tree had a little disagreement, I was in a hurry and went bought a Stihl MS 390 to replace the damaged saw. After poking around here for a while I decided to tinker a little bit with my muffler in an attempt to get a little more out my saw. Muffler mod was no problem but when it came to adjusting the carb I was a little out of my comfort zone so I dropped it off at my dealer where I purchased the saw and he gave me the riot act...."Why would you screw around with the muffler" " Opening up the muffler will gain you nothing" " This is the last time I will work on your saw, since the warranty is no good since you tinkered with the muffler"

Thank god I was the only customer in the store....

He told me that it would be a week and a half before he would have enough time to adjust the carb, I told him that I needed the saw for the weekend and you would of thought I had asked him to cut off one of his arms.......

Another dealer that hasn't learned we are in the service industry. While he is in his right to tell you your warranty is violated by making mod's, his approach was a bit off. I'm guessing you are either in Philly or Pitt. Both areas seem to have the same attitude, do what I tell you or get out.

If you're near Philly, bring the saw by and I'll show you how to adjust your carb. If not, let me know what area and I'll direct you to a decent service facility.

Either way, find a new dealer.

 

[barneyrb]

YZ as in YZ Yamaha?

And what do you mean by "Piped"?
Does that mean putting a motorcycle spannie on it?

Yep and Yep....had some wicked torque, almost came out of my hands when I blipped the throttle. Pipe came around and exited to the right side of the rear handle.

 

[Taxmantoo]

And what do you mean by "Piped"?

Some pics here:
http://arboristsite.com/showthread.php?p=1011824#post1011824

 

[Smokerr]

Thanks for the reply, I had figured that the expansion chamber of a modern motocrosser (and quite possibly old 1990 models like mine are) would be more advanced but the rest I just didn't know, making the timed cuts makes sense.

As horsepower is a function of torque multiplied by revs then divided by 5252 (If my memory serves me right) to increase the power of the saw it either has to rev higher or produce more torque in order to produce more horsepower.

Do the saws rev higher after the muffler mods or produce more torque, or maybe even both?

I don't have the foggiest notion about saw tuning so am pretty much in the dark.

Regards Scott.

Me to, so I wrote Stihl and asked what the deal was.

Upshot was that while the saw free wheels up to 13,00 some RPM, it cuts best at 9500.

My guess is that is where the hp and torque peak are.

While it may be nosier and run fast, it probably has no affect on how well it cuts. Videotapes and people that do that stuff have a vested interest in proving they did something, otherwise they have to admit it was a waste of time.

Me, I am happy with how mine cuts. If I want more cutting ability, I will get a bigger saw (not going to happen, what I have works perfectly fine.)

 

[Rounder]

That's why I like my Stihl Dealer... You tell them you muffler modded your saw, and they say, "Why stop there?" LOL

They've made bike-saws, snowmobile-saws, tweaked 090's... They know what's up. :greenchainsaw:

Who do you business with up there? Steve's in Lolo is the only decent shop I've found in the state yet.

 

[scotclayshooter]

Me to, so I wrote Stihl and asked what the deal was.

Upshot was that while the saw free wheels up to 13,00 some RPM, it cuts best at 9500.

My guess is that is where the hp and torque peak are.

While it may be nosier and run fast, it probably has no affect on how well it cuts. Videotapes and people that do that stuff have a vested interest in proving they did something, otherwise they have to admit it was a waste of time.

Me, I am happy with how mine cuts. If I want more cutting ability, I will get a bigger saw (not going to happen, what I have works perfectly fine.)

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There you go thats the same saw modded by Timberwolf Im betting its cutting nearer to 13000rpm than 9500.
Looks like the ported cut twice as fast going by the times.

 

[JJay03]

My dealer kind of seemed like they were against modding the muffler but not enough to act like that d'bag. I bought the parts from them today to do the muffler mod for the 361 on this site.

 

[scattergun13]

Yeah cause the EPA over here chokes the things out. Pretty soon were going to have saws that run on flowers and spit out purified air.

Sounds like your describing the mighty ms361!:hmm3grin2orange:

 

[demographic]

Me to, so I wrote Stihl and asked what the deal was.

Upshot was that while the saw free wheels up to 13,00 some RPM, it cuts best at 9500.

My guess is that is where the hp and torque peak are.

While it may be nosier and run fast, it probably has no affect on how well it cuts. Videotapes and people that do that stuff have a vested interest in proving they did something, otherwise they have to admit it was a waste of time.

Me, I am happy with how mine cuts. If I want more cutting ability, I will get a bigger saw (not going to happen, what I have works perfectly fine.)

I would expect the peak torque to be at lower revs than peak horsepower, thats the way it works with any bike dyno chart I have seen anyway.

The torque (in foot pounds) and BHP lines on the graph cross over each other at 5252 revs as well.

As a matter of interest, does anyone have any dyno charts for saws?
Is there even a dyno that gets used to measure chanisaws or am I just asking daft questions?

 

[JJay03]

That would be sweet a chainsaw dyno with tuning software . Screw the tach ill mount a afr gauge on my 361. Need to ad a check engine light too.

 

[demographic]

Screw the tach ill mount a afr gauge on my 361. Need to ad a check engine light too.

I assume that AFR guage is an Air Fuel Ratio guage?
Theres tachos that get used to racing cart engines that all you do is wrap the sensor lead round the cart HT lead and it tells you the RPM, is that how the saw tachos work?

I read somewhere about using a tacho to set the saw up but have never seen one yet.

 

[Bowtie]

I would expect the peak torque to be at lower revs than peak horsepower, thats the way it works with any bike dyno chart I have seen anyway.

The torque (in foot pounds) and BHP lines on the graph cross over each other at 5252 revs as well.

As a matter of interest, does anyone have any dyno charts for saws?
Is there even a dyno that gets used to measure chanisaws or am I just asking daft questions?

Timberwolf posted up some charts on muffler mod gains per size on an 026 I believe. There is a lot of info there. Have to do a search to find it, I cant remember the thread title.

 

[JJay03]

I assume that AFR guage is an Air Fuel Ratio guage?
Theres tachos that get used to racing cart engines that all you do is wrap the sensor lead round the cart HT lead and it tells you the RPM, is that how the saw tachos work?

I read somewhere about using a tacho to set the saw up but have never seen one yet.

I havnt bought one yet but I assume it just clips to the spark plug wire sort of like a timing light.
http://www.baileysonline.com/itemdetail.asp?item=17122&catID=

 

[kevin j]

madsens had a saw dyno at one time. ran an air fan wheel I think. probably long gone with the higher rpms required now.

dynos don't tell everything, but they do cut through all the bs, that would be the true test of numbers

 

[demographic]

dynos don't tell everything, but they do cut through all the bs, that would be the true test of numbers

One of the bike forums I go on had lots of posts about this or that exhaust being better than another and how the new blah blah blah expansion chamber caused the bike to "Flat out haul" and so on.
Bearing in mind the fact that the bikes in question weren't exactly too short of "Flat out haul" in the first place and the only place to test them properly offroad was somewhere very open which isn't many places.
Its certainly not that easy to open them right up on a motocross track so I always felt that the seat of the pants dyno wasn't worth too much with bikes.

Then along came a few guys who joined the site that put the effort in to test any exhaust they could get their hands on and all of a sudden the BS calmed down a lot when they posted the differences between the pipes.

It was quite interesting to see.

Not suggesting that this is anything like that situation, I was just wondering if there was any real documentary evidence to the gains.

I will have a search for those dyno charts as I think it will teach me the answers to quite a few of the questions I have been asking tonight.

Cheers, Scott.

 

[fourfivefour]

Why does Stihl produce a $50. dual port muffler cover if it does nothing?
Ask your dealer that!