Muffler mods

i beleve you can find them on ebay . h

what kind of saw do you have?

For the 5100 I was told to just drill a 3/8" hole on the right side. Don't forget to richen your carb. adjustments.
If you're worried about sparks you might have to weld on a washer to hold a screen.
If you do it post back here about how much power gain you notice. I may do mine once it's out of warranty.

I did my 310 by drilling a couple of holes in the recessed area behind the cover and then grinding away some of the cover to promote the airflow. Had to richen the carb a 1/4 turn. Haven't yet done anything with the 5100. Might leave that one stock because I need one quiet saw. The 310 went from loud to OH MY GOD I CAN'T THINK, LOUD. But that's what earmuffs are for.

My 5100 sure seems nice and quiet but I don't have anything to compare it to. It does more than I ask it to as is so maybe I'll leave it stock.
Maybe not. :cheese:

I got one done on the west coast for my 361. It def. runs better with it than it did without. Ran it a bit richer, but other than that, it wasn't a bad deal. Open them up and they WILL run better. Key with any motor: run more fuel and get out the exhaust quicker. Pretty simple.

Wood Fox said:

ms310 & dolmar 5100

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the dolmer i believe has a rev limiter of 13500 so to port the muffler you have to chance out the "coil pack" the solo coil pack will work. (this will take some work) the stihl not sure if that model has adjustable carb? by porting the muffler you will be gaining rpm's my 460 runs around 14,200 if you dont have an adjustable carb you can change it out pretty cheap,there alot more to it than just drilling a whole.Sthil sells a dual port cover that already has spark screen on it

The impression I got from the posts on Arboristsite was that there wasn't as much benefits from doing the muffler on a Dolmar as there was on some of the other brands. The feeling seemed to be that the Dolmar got more out of the saw in factory tune than some of the other brands, which is one of the reasons people are so impressed by how they work compared to comparable H/S models in stock form, but that because they got more out at the factory, there was less potential for improving things with aftermarket mods...

My own personal feeling is that I live and do most of my cutting in a suburban area, and would rather run a saw that was quiet and less likely to severely bother the neighbors.... Besides, I'm quite happy with the performance on my 7900.

Gooserider

smokinj said:

the dolmer i believe has a rev limiter of 13500 so to port the muffler you have to chance out the "coil pack" the solo coil pack will work.

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I think you may be thinking of the 510. The 5100's max. recommended rpm is 14,500 and I'm not sure it's limited to that. Mine's @ 14,300 stock.

Gooserider said:

The impression I got from the posts on Arboristsite was that there wasn't as much benefits from doing the muffler on a Dolmar as there was on some of the other brands. The feeling seemed to be that the Dolmar got more out of the saw in factory tune than some of the other brands, which is one of the reasons people are so impressed by how they work compared to comparable H/S models in stock form, but that because they got more out at the factory, there was less potential for improving things with aftermarket mods...

My own personal feeling is that I live and do most of my cutting in a suburban area, and would rather run a saw that was quiet and less likely to severely bother the neighbors.... Besides, I'm quite happy with the performance on my 7900.

Gooserider

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Your right up to a point dolmer has a great factory setting and it cant be changed because of the limit on the coil pack now that can be change out and run it at say 14200 rpm (with muffler mod)(solo coil pack) is is it worth it? (thats up to the user) My 460 runs in the range of 14200 to 14300 stock i beleave is 12800rpm no one that i know has none the dolmer 7900 but there is a few that have done the 5100 it cost more to do a dolmer and the gains are less. "sorry the max rpm on the 5100 is already 14500 rpm's" wouldnt mod that saw at all wow just adjust the h screw all the way out! the 7900 is max out at 13,500

Gone a bit astray, however, any time you can get the exhaust out faster, the saw will run cooler. This is great for any motor. I'll try and run most of my saws in this way if I'm going to run them as my standard cutting saws. Most take a bit more time than the Stihl big boys (can get the ported covers). But even though they may not be able to run higher, you will save some heat always a good thing.
Chad

if you let more exhaust out you are changing the tuning of the saw and can cause damage quick. but what the heck put a hole in it

I don't know guys, I think some folks think that when a engine is loud that it has alot of power. Not always the case. Exhaust systems and air filters are tuned to the performance curves of the engine and the targeted operating range. I've seen a few atvs where guys put on straight pipes and then get beat by a quiet stock bike or guys trying to mod their expansion pipes on their dirt bikes and completely losing the powerband. And going over the rev limiter is asking for trouble but it even amazes me that these new saws rev as high as they do.

And yes, a engine is a air pump. The more air you can pump the more power you can make but at what trade off. More friction, more heat, and shorter life span. There is no "replacement for displacement."

Garnification said:

I don't know guys, I think some folks think that when a engine is loud that it has alot of power. Not always the case. Exhaust systems and air filters are tuned to the performance curves of the engine and the targeted operating range. I've seen a few atvs where guys put on straight pipes and then get beat by a quiet stock bike or guys trying to mod their expansion pipes on their dirt bikes and completely losing the powerband. And going over the rev limiter is asking for trouble but it even amazes me that these new saws rev as high as they do.

And yes, a engine is a air pump. The more air you can pump the more power you can make but at what trade off. More friction, more heat, and shorter life span. There is no "replacement for displacement."

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Well said my good man! I see it all the time with snowmobiles I myself have been a victim of such practices.......cost me literally untold thousands only to be beat by stock machines and have my sled grenade three or four times over two years.
My saws stay stock! And my 07 f1000 is nearly stock to ! lol (I will need professional help for that addiction).

But seriously you are right on target I just upgraded to a new 576xp as well as a 346xp these saws are tweaked to run for maximum power vs efficiency with x-torq technology. You mess with that factory combination your asking to by a new saw every year.

Garnification said:

I don't know guys, I think some folks think that when a engine is loud that it has alot of power. Not always the case. Exhaust systems and air filters are tuned to the performance curves of the engine and the targeted operating range. I've seen a few atvs where guys put on straight pipes and then get beat by a quiet stock bike or guys trying to mod their expansion pipes on their dirt bikes and completely losing the powerband. And going over the rev limiter is asking for trouble but it even amazes me that these new saws rev as high as they do.

And yes, a engine is a air pump. The more air you can pump the more power you can make but at what trade off. More friction, more heat, and shorter life span. There is no "replacement for displacement."

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your right there is alot more to it than exhaust air filter if none right it can bring 9-20 percent more power over stock done wrong iam sure it will go the other way! Tuning the saw is key with or with out a muffler modd.I too am shock that the 5100 is rate at 14500 rpm stock and thats a big reason why the revue are so high! (14200 is the sweet spot on the pro stihls) if you dont know how to tune a saw dont do any mods at all

I would also point out that 2-stroke engines actually NEED exhaust backpressure for optimal performance - take the muffler off and you'll pump lots of air through the engine beyond a doubt, and wonder where your performance went at the same time... In practice the back pressure from one exhaust stroke helps to KEEP the incoming fuel charge for the next stroke in the cylinder instead of following the exhaust gasses out the muffler port - Indeed a properly tuned system will actually time the sound waves of the exhaust to actually pull some fuel charge through the cylinder into the muffler, then stuff it BACK into the cylinder just before the port closes.

A large part of the design work that goes into a 2-stroke is "shaping" the power output - there is a tradeoff between a low flat powerband where the engine makes moderate power across a wide RPM range, or giving up power in most of the range in exchange for a higher narrower peak. The muffler modders are mostly changing the shape of that power output curve - making it have a higher peak and a narrower range. The result will be a saw that cuts better if it is in the RPM "sweet spot" but will bog down faster and worse as the RPM's fall off...

At least that's the theory, how well it applies in practice may be grounds for debate.

Gooserider