Stihl MS260 - 044 Carb and Echo filter swap...

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tacomatrd98

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I've been fiddling around with this in my spare time for awhile and finally got it to what should be a functional point. I've always thought it would be cool to have a pleated "HD" style filter on a 026/260 so I set out to do just that. Figured while I'm at it, may as well stuff an 044 carb in there too.

At this point it is just a tank, I don't have the motor done yet to be able to run it. Put new bearings, seals etc in, but don't have the jug ported yet. This saw is a parts bin saw from my stash of junked 026/260's. Time is limited these days and I couldn't wait any longer to share my craziness.

The carb is a Zama C3M off an 044. The white filter base is a modified Echo CS400 part. The air filter is CS400, unmodified. The nut/knob is an OEM stihl air filter nut from a 460. The rear sealing plate is just alum. sheet I cut into a circle and drilled for the knob. The aluminum plate that adapts the carb to this filter base is custom made from 3/8' thick aluminum. I countersunk the holes on the carb studs so the plate is what holds the carb tight, then drilled and tapped 3 holes for the filter base to fasten tight to the adapter plate. One thing I wanted was to retain the factory master control lever. For this I made an arm that attaches over the stock choke flipper and will activate the carb mounted choke in the 044 carb. It took some tweaking to get this just right to allow the arm to still go to the off position yet fully open the choke and work in the 1/2 throttle position. Probably made and scrapped about 5 of these little guys till I got it just right. It does not need to be bent at a 90 like in the pics to work with this filter setup, however I made it that way so it WILL 100% work with a stock filter and cover. To run the stock filter you have to swap out the carb studs and remove the choke flap and seal off the choke arm hole in the filter. I did this incase this setup blows and I decide to just run the stock filter on the 044 carb. It doesn't look the best right now but this is my prototype setup. Eventually going to get a machinist friend of mine to remake all the parts with real machine tools and smooth up everything. I did everything except tapping the holes with a burr in a die grinder, hacksaw, file and a drill.

One thing that made this a major PITA to get all lined up is the offset carb housing on a 260. I never realized they are not symmetrical. Not a big deal, but I wanted the filter to end up centered, and it didn't quite work out that way. I'm working on a custom 2 piece cover like an 044 uses to run on an 026 that I'm building along side this one. I cut the back half out of a stock filter cover and am making a small version of an 044 type back cover. I have not gotten it ironed out yet. I'm getting closer, but it isn't picture worthy yet lol.

As far as fitting the carb, I will be using an 038 intake boot, 026 clamp and boring the tank slightly to fit the boot. To actually get the carb in the tank, I only had to drill one hole for the idle screw and shorten and re-grooved all three adjustment screws. I also removed the grommet on the LH side of the carb box as it made the throttle shaft drag a bit. I shortened the fuel inlet and re-positioned it and it seems like it will work just fine. I also had to shorten the horizontal portion of the choke arm a tad as well.

Let me know what you guys think.

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Fwiw I think it's great. A carb swap on a 26 with a pleated filter has been bouncing around ma head. I've been looking at my 261 comparing to my 26.

Lots more air/fuel with you have done. Nice!
 
Fwiw I think it's great. A carb swap on a 26 with a pleated filter has been bouncing around ma head. I've been looking at my 261 comparing to my 26.

Lots more air/fuel with you have done. Nice!
Thank you.

I wanted to use the 241/261 filter so bad I could taste it but it is physically too big to be feasible with how narrow the 260 is compared to the 261. Stihl did a great job on the 241 carb box. That filter is huge but they managed to tuck it in there and still keep the top cover low and narrow. The other problem is the twistlock design. You have to use their proprietary base and it would have been a pita to incorporate that as well.
 
Have you considered just using a velocity stack and a clamp on K&N filter with an Outerwears?
I have, but that would be too easy and make too much sense ;). I originally wanted to keep it under the stock filter cover but this was as close as I could get for now. This is my first attempt at this. I want to run the saw with it to see how it behaves before I spend too much more time on a 2 piece cover version which I hoping to make look like a little 044/064 HD filter cover.
 
You're spot on that the stock air filter is a huge bottle neck. It costs nearly 2,000 RPMs on mine. If I want to race, I just remove the filter, lol. For permanent filtration improvement, I don't see anyway around doing something like you are. Nice work.
 
I love my 260 with the 044 carb on it which I did with Blsnelling's how to post.

On the dyno, the 260 is as powerful as a ms362 while being smaller and lighter yet.

I'm still using a stock filter but the fleece has been cut out and replaced with foam on both sides.

There's only 1,200 rpms difference between filter and no filter.

I raced a modded 026 that still has the factory carb but bored out.

With no air filters on both, they're nearly the same. He wins just a bit more.

That's with 16" bars and 325 chain.

Then we put 24" on both with 3/8 chain, my 260 wins hands down over and over with the filter on.

He couldn't win with his filter on as he lost too much power compared to no filter.

Mine made better torque with the filter.

I have not made any attempt to make the choke work unless I take the filter cover off and use a screwdriver to hold it on.

But for now, no one would think my 260 is modded at all as it looks completely stock with only the long bar as the give away.
 
Got the saw running today.I have some bugs to work out as it wont hold a tune very well. I think the carb is the culprit. I put a new kit in it but did not mess with the welch plug. I will agree the bigger carb gives a 260 a much different attitude. I didn't get the tach out as the wife was hollering about me making us late for dinner plans but my ear says it has to be around 15,000 with filter present. That was sounding good, nice burble on top. Im anxious to get the kinks worked out and buzz up some stuff with it. I made a few cuts with it but nothing much. I want to get it sorted out before I cut a lot with it. Probably be a little while til I get some more time with it but I will try to get some videos once I get it all straightened out.
 
15,200 rpms is what I got in mine with the modded filter. 17,400 without.

But my last race, the saw inhaled something without the filter. Worn the intake skirt down and now it can't keep the mix in. Sprays gas/oil back out the carb.

Saw still runs fine, but only with filter on. Now 14,400 rpms. Booo!!!

Getting a new piston.
 
I've been fiddling around with this in my spare time for awhile and finally got it to what should be a functional point. I've always thought it would be cool to have a pleated "HD" style filter on a 026/260 so I set out to do just that. Figured while I'm at it, may as well stuff an 044 carb in there too.

At this point it is just a tank, I don't have the motor done yet to be able to run it. Put new bearings, seals etc in, but don't have the jug ported yet. This saw is a parts bin saw from my stash of junked 026/260's. Time is limited these days and I couldn't wait any longer to share my craziness.

The carb is a Zama C3M off an 044. The white filter base is a modified Echo CS400 part. The air filter is CS400, unmodified. The nut/knob is an OEM stihl air filter nut from a 460. The rear sealing plate is just alum. sheet I cut into a circle and drilled for the knob. The aluminum plate that adapts the carb to this filter base is custom made from 3/8' thick aluminum. I countersunk the holes on the carb studs so the plate is what holds the carb tight, then drilled and tapped 3 holes for the filter base to fasten tight to the adapter plate. One thing I wanted was to retain the factory master control lever. For this I made an arm that attaches over the stock choke flipper and will activate the carb mounted choke in the 044 carb. It took some tweaking to get this just right to allow the arm to still go to the off position yet fully open the choke and work in the 1/2 throttle position. Probably made and scrapped about 5 of these little guys till I got it just right. It does not need to be bent at a 90 like in the pics to work with this filter setup, however I made it that way so it WILL 100% work with a stock filter and cover. To run the stock filter you have to swap out the carb studs and remove the choke flap and seal off the choke arm hole in the filter. I did this incase this setup blows and I decide to just run the stock filter on the 044 carb. It doesn't look the best right now but this is my prototype setup. Eventually going to get a machinist friend of mine to remake all the parts with real machine tools and smooth up everything. I did everything except tapping the holes with a burr in a die grinder, hacksaw, file and a drill.

One thing that made this a major PITA to get all lined up is the offset carb housing on a 260. I never realized they are not symmetrical. Not a big deal, but I wanted the filter to end up centered, and it didn't quite work out that way. I'm working on a custom 2 piece cover like an 044 uses to run on an 026 that I'm building along side this one. I cut the back half out of a stock filter cover and am making a small version of an 044 type back cover. I have not gotten it ironed out yet. I'm getting closer, but it isn't picture worthy yet lol.

As far as fitting the carb, I will be using an 038 intake boot, 026 clamp and boring the tank slightly to fit the boot. To actually get the carb in the tank, I only had to drill one hole for the idle screw and shorten and re-grooved all three adjustment screws. I also removed the grommet on the LH side of the carb box as it made the throttle shaft drag a bit. I shortened the fuel inlet and re-positioned it and it seems like it will work just fine. I also had to shorten the horizontal portion of the choke arm a tad as well.

Let me know what you guys think.

View attachment 445347
I've done similar and now I wont start. How did you do away with enough vacuum to draw fuel thru the carb?
 
Here it is. I also have the vacuum there but the fuel wasnt. It rips! I swear it throws, on an undercut, chips 20-25 feet away.
 

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I have thought about trying a bigger carb on my 026, but every time I read about it it comes back ot it runs good WOT, but is extremely finicky every where else. My 026 is my go to saw for just about everything, and I just can't have that. Realisticly the WT194 hasn't left me wanting for more.

3/8 Round back when it was still cold:
View attachment VN20230219_185136.mp4

And 3/8 square, still working on my grinding....
View attachment VN20230531_213131.mp4


The thing just plain works, 4 strokes around 16,500-16,700 last time I had a tach on it.
 

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