Porting an Echo 355T

[MemphisMechanic]

Retimed the

I agree 109 exhaust is in the ballpark for a lot of modded Echoes. But if you’re starting at 119, I wouldn’t go that far. Maybe 114-112. You can’t put it back, but you can take more later.

What is stock timing for the transfers? Curious what squish is as well.

I re-timed the saw on a lot more sleep today, oh and let’s tag @huskil because he might find this interesting as well:

73 Intake
119 Exhaust
124 Transfers

There’s no way that I can modify the upper transfers with my current tooling in this tiny bore, so I’m inclined to add perhaps 3-4 degrees of exhaust height and not radically increase the blowndown.

Love him or hate him, TinMan did exactly that to a CS-590 on youtube recently by moving the saw to 25 degrees blowdown. Sure enough, it ran like garbage.

 

[smokey7]

You got your numbers mixed up again fella. You must have intake 73 exhaust 119 transfers 135

 

[Nutball]

Love him or hate him, TinMan did exactly that to a CS-590 on youtube recently by moving the saw to 25 degrees blowdown. Sure enough, it ran like garbage.

Maybe he did something else wrong. 25deg blow down in a 590 shouldn't run like garbage.

There have been many saws with roughly 30deg blow down that have run very well, so I wouldn't worry too much about it as far as basic gains go. Most of the change in performance will come from the exhaust height. But Echos are ported for torque, so it would be good to keep the exhaust on the low side especially on a small engine, but Echos can perform well with high exhaust too. Are you confused yet?

 

[MemphisMechanic]

You got your numbers mixed up again fella. You must have intake 73 exhaust 119 transfers 135

Oops. Correct. Fixed!

Most of the change in performance will come from the exhaust height. But Echos are ported for torque, so it would be good to keep the exhaust on the low side especially on a small engine, but Echos can perform well with high exhaust too. Are you confused yet?

When it comes to porting? Always, a wee bit. That’s what makes this fun.

Squish was .049” by the way. Staying that way obviously, without the ability to do a gasket delete.


I’m porting it tonight, finally back on this project. Going to add just a pinch of intake and exhaust. Keep it small.

 

[MemphisMechanic]

Ported the saw and timed it after final assembly:

76 Intake (+3 advanced)
113 Exhaust (+6 advanced)
124 Transfers
Squish is obviously still .045”

Left upper transfers alone to increase blowdown.

Opened the lowers up, then put the stuffers back in.

Raised exhaust roof but did not widen. Too awkward given the 90* turn you’re snaking your cutter into..

Lowered intake floor, but here I also widened and raised the roof.

Will reassemble and test it out in the next few days. I’ll have before and after footage to share via YouTube.

 

[MemphisMechanic]

Finished! I filmed a complete teardown and reassembly video on this saw. There’s barely anything on Youtube related to the 355.

I’ll probably wait to slap it onto youtube once the saw is broken in so that I can see what it really winds up behaving like, and get some footage of it making money up in a tree. (It had less than 5 minutes of runtime when I tore it apart.)

 

[Nutball]

I think it will cut much faster with 3/8 .043 chain.

1/4 .043 is best for under 30cc saws.

 

[Red97]

If I can get motivated I'll start my 355 build after work....

Hope it don't fight too bad.

 

[Ketchup]

Couple questions:

Does 355t have seals that fit over the bearings?

What size is the bore? 40mm? 10mm wrist pin?

 

[Nutball]

39mm bore, it has seals that slide on beside the bearings like most any clamshell

 

[MemphisMechanic]

I think it will cut much faster with 3/8 .043 chain.

1/4 .043 is best for under 30cc saws.

I’m going to test it both ways and find out!

Although it’ll probably be run with the 1/4” bar no matter what. The saw was bought to climb and work, not for racing. The Panther bar does wonders for the saw’s balance.

I like the idea of a 16” to keep me further away from the action, but the ECHO bar made this saw outrageously tip heavy.

 

[MemphisMechanic]

Couple questions:

Does 355t have seals that fit over the bearings?

What size is the bore? 40mm? 10mm wrist pin?

I didn’t measure anything. But here’s a crank/seals pic:

 

[MemphisMechanic]

Sank it into a 14” ash tonight and cut put a few face cuts into it.

I’m thrilled. Let’s just say that.

It was 34* and raining like mad, so I did a couple of quick cuts and returned her to the workshop. Video soon.

 

[MemphisMechanic]

Well. I built the saw just in time. An ice storm took a 23” ash tree down and dropped it on the corner of the house on Thursday afternoon. I used the 355T while dicing up everything on the roof including at least a dozen cuts in 6-8” wood.

It pulled through it wonderfully, although the carb still needs some tweaking to get it to idle right. I’m really liking the 1/4 chain and that flyweight 16” bar, too.

Then I went to work with the ported 044 and fed the tree to the log splitter, after installing a new service mast on the house so they could reconnect the power lines.

 

[MemphisMechanic]

The 355 had it’s first climbing gig yesterday: cleaning up storm damage in a 34” white oak.

I cut a couple of cookies off of a 7” limb just to get a little bit of video. Still needs tuned, it isn’t broken in, etc. That said, I’m really happy with it…

https://www.reddit.com/r/path%3D%252Fr%252FChainsaw%252Fcomments%252Ft4ysx4%252F

 

[00wyk]

For anyone reading this in the future? Do it his way.

Mine seems to flow very well… but his exits through the factory opening in the cover over the muffler. Mine required significant trimming to avoid melting plastic near the muffler’s exit.

Or alternatively, just use a cut-off and cut the bottom of the exhaust tab and bend her open a bit:

 

[00wyk]

Also, tuning a stock 355t is a pain sometimes let alone a ported one. I suspect it may just want more carb.
Mine floods easily. It just isn't getting the air it needs sometimes, and it wants to run leaner than I am comfortable with.
But I think I am just gonna have to let it win and lean her out and just use racing bike oil. It's as cheap as most other oils here anyways.

 

[Ketchup]

A lot of the small Echos run variations of the same WT carb. So far 490, 4910 have the largest Venturi I have found. The main carb body can take whatever specific covers, veins (and linkages) that a different saw has. Sometimes you have to drill a pulse hole. It works on a 2511 but it’s actually too much carb. Might be perfect on 355t.

 

[Nate6421]

Hey All, does anyone have a solid idea of which carb to upsize to on the 355t? The reason I ask is i have done a limiter cap delete, muffler mod with rounding all square edges, port matching, and also some light exhaust port work light widening and real light lowering. The mid is always lean, I can get the idle great, and top great, mid is always lean.

Aside from the lean mid, the saw runs great if you are comfortable with the chain takings a couple seconds to come down to a stop. Which I want to fix.

Once I get my other top handle going, (201t thats been having issues) I was planning to take the carb apart and bend the needle tab down a touch, hopefully richening everything so I can match the idle and top to that.

 

[Nutball]

I thought I heard somewhere why the 355t sometimes goes a bit lean coming down from idle. I had one do it, then it stopped. Many saws will get somewhat lean at half throttle. The carb might just need a different main nozzle if it is using the thin black rubber check valve that also causes many 590's to have lean idle problems.