tell me about chainsaws and epa

[RollCOAL84]

This is my first post on this site. i did a bunch of searching and wasnt able to find anything on my question. if there is something on this info could someone please direct me to it??

I have a husky 351 and a 371xp both have walbro carbs. i was wondering what i could do, if anything, to make this run more efficiently. my buddy was saying something about this screen like gasket in the carb that is supposedly an epa mandated addition but robs it of of power. also the muffler has stuff in it that you can remove to cause it to run more efficiently. i wasnt able to find any real info on epa numbers. is there anyone out there that can tell me how the numbers work? as far as i know each set of numbers represents a "generation" of epa regulations. again if ive asked a question that has already been asked please direct me to the info im looking for thanks

 

[SawTroll]

Those saws are both too old to be very affected by the "EPA devil", but will nonetheless gain from a muffler mod anyway. As always (well mostly) a larger carb venturi would help as well. If that isn't enough, you can change the cylinder and piston to better/larger ones - and/or having the top end ported by an expert.

 

[mad murdock]

Most saws built in the last 20+years have a screen in the muffler that serves as a spark arrester. This is due to rules put in place by states and Feds for power equipment used on state and federal woodlands, including logging equipment( skidders, yarders, dozers, saws, etc). A muffler mod usually includes removing the screen and putting more holes in the internal baffling to remove restriction to airflow, making the engine run better producing more power.

 

[woodyman]

I don't know about the 351 muffler but your 371 muffler is just a tin can with a 1/2 hole and a screen on it.Adding an extra port and tuning the carb will give you some extra power.On the 371 you can cut a hole through the muffler support bracket and muffler and put a screen inbetween for an easy muffler mod or drill a hole on the side of the muffler and install a Husqvarna 288 deflector.Both work well.

288 deflector on 044 Stihl.

Or go nuts on it.

 

[testlight]

Feel free to correct me if I'm wrong. If I remember right the EPA grades, (I thought they were letters, but maybe they are numbers) Represent kind of a grade. The really clean running machines, like a four stroke generator came run for a long time before they make X amount of pollution, on the other hand a big, old 2 cycle chainsaw only runs for a short time until it makes the same amount of pollution, so it would be on the opposite end of things. You may notice a newer saw of the same model to have a different rating. The newer saws may have catalytic converters, restricted, non tunable carbs, and even the new school strato-charged engines.
Sorry to be so vague.
Bottom line is like others have said any saw that old can't have much for emissions. Do they have the little plastic limiters on the carb adjustments? If so they are the early ones and they can usually be cut off with dikes, or something along those lines.
Peace

 

[Evanrude]

If you're talking about the fuel inlet filter screen in the carb, I wouldn't suggest removing that. Its there to protect your carb from any foreign material that made it past the filter in the fuel tank. Open up a carb some day and you'll likely see there is something it has caught.

 

[StihlPoulan]

EPA has been trying to limit emissions in 2 strokes (motorcycles, snowmobiles, etc)for quite some time.

Someone else on the forum might be able to give you more advice but my 1994 Poulan has adjustable carb (H,L) but ~2000 Stihl has doesn't have a H screw.

 

[SawTroll]

EPA has been trying to limit emissions in 2 strokes (motorcycles, snowmobiles, etc)for quite some time.

Someone else on the forum might be able to give you more advice but my 1994 Poulan has adjustable carb (H,L) but ~2000 Stihl has doesn't have a H screw.

Those Stihl saws was an exception to the general rule, and wasn't typical of the situation in 2000.

 

[Boleclimber]

This is my first post on this site. i did a bunch of searching and wasnt able to find anything on my question. if there is something on this info could someone please direct me to it??

I have a husky 351 and a 371xp both have walbro carbs. i was wondering what i could do, if anything, to make this run more efficiently. my buddy was saying something about this screen like gasket in the carb that is supposedly an epa mandated addition but robs it of of power. also the muffler has stuff in it that you can remove to cause it to run more efficiently. i wasnt able to find any real info on epa numbers. is there anyone out there that can tell me how the numbers work? as far as i know each set of numbers represents a "generation" of epa regulations. again if ive asked a question that has already been asked please direct me to the info im looking for thanks

The definition of efficient is paramount to your quest.

Does efficient mean to spew the least amount of unburned fuel into the environment?

Does efficient mean to cut the most wood in the shortest amount of time at a cost of fuel mileage?

EPA regulations have lead to saw design evolution but so hasn't ergonomics. Take the 371 versus previous 272 model. The 371 has better vibes and was reported, by a local dealer, ( not sure if that counts) to have cleaner emissions at the time. Added to that the 371 is slightly ahead of a 272 in the cutting speed. In my opinion this is good. A cleaner saw and better performance.

That said, I personally am reluctant to harp on EPA regulations. In my opinion they have helped saw evolution along. Excluding the High & Low speed limiter caps. I have witnessed a few saws melt down from the factory settings.

I do like porting my saws though. Why leave any power on the table when I know how to extract it!