Mod for my 034

[Countrybois]

I know this is addressed in other area's here, I just haven't been able to find it for the 034. Anyone have a recommendation for modifying the muffler? It's easy enough to open 'er up and start drilling holes, but is there a 'better' way to do it? Do I need to be concerned with keeping some back pressure?

Z

 

[glens]

Depending on the vintage, you might not gain as much power as you do noise.&nbsp; If it's got non-limited carb adjustments on the original carb, I'd suggest getting an extra muffler for it if you can, and play around with <i>it</i> so you can restore the stock condition if you have no success.&nbsp; Search for "exhaust port size" to perhaps find recommendations for outlet openings.

Glen

 

[Countrybois]

I'm not sure what year it is, early to mid '90's I'd guess. It's an 034AV with fully adjustable carb. The muffler HAD a spark screen, beneath what looks like a deflector that sits beneath a vented 'cover', which I assume is just an additional heat shield. Inside, the exhaust port goes into a square 'box' with a half-dozen holes in either side. On the inside of the cover is another 'deflector' that covers the outlet and has a single row of holes on it's side, maybe 4 or 5 holes.

 

[rmihalek]

Measure the area of the exhaust port on the cylinder. Then, you want to have your muffler with an opening about 80% of this size to create sufficient backpressure. So, add up the area of all those little holes inside the muffler and make sure they total up to 80% of the area. Then, if there's a spark screen, you'll have to come up with some way of determining the "open" area of the screen. Maybe take a 1/4 inch square section, see what % of that is open and then extrapolate to the area of the entire screen. It sounds as if the screen is gone, so you may not need to worry about this.Then you'll want to be sure that final exit on the muffler is also at 80% of exhaust port size and you're good to go.

Just make sure you can adjust the jetting in the carb to compensate for the lower restriction in the muffler. Making more power requires more fuel.

 

[Countrybois]

I'll let you know how it turns out. Thanks for the input.

 

[glens]

I guess what I was getting at is that with a pre-EPA saw (which it seems you have) you often run the high risk of merely making it louder at best.&nbsp; It's difficult to separate the noise from the perceived performance sometimes, and the louder version <i>seems</i> to cut faster when just going by the seat-of-the-pants method.&nbsp; (much like when auditioning loudspeakers where the pair that's even the tiniest bit louder invariably sounds better in comparison, even when it wouldn't when great care is taken to precisely calibrate the volumes)

I strongly urge you to get an old muffler to play with in your experiments.&nbsp; The two reasons being that you can restore the saw to its stock condition (the engineers didn't do things in a haphazard manner) and so you can quickly swap them (and make necessary [re]adjustments to the carb) for timed comparisons to achieve a proper comparison.

Glen