Q's on 'proper muffler-modding' (and basic/entry chainsaw mods in-general)

[ArborOdyssey]

On 18/02/2020 at 14:35, spudulike said:

Going back to the dodgy port, remove the cylinder, get a carbide burr on the flash and open it up so the port matches the shape of the main cast port shape. DO check that there are no ring ends near the port BEFORE you grind and also check that the piston skirt will cover the port completely on its full travel up and down.

Bevel the port edges after grinding so the ring doesn't snag and then rebuild.

Ok I'm LOVING this, am ready to buy a 2nd unit (planning-to, actually) anyway and do think it'll tear when that's opened (would it be dumb to 'port&polish' the air-inlet port on the block now as well?  Seems like it'd be smart, not only to 'match-up' the intake/outlet portions of the block but also just because it seems you'd want more availability pre-cylinder than post -- and it'd probably make sense at some point so since everything's opened up already...)

 

My die-grinder is up to the task, I usually get the cheap rasp bit (1/4" shank) kits from Harbor Freight, will get the nice / fine-tipped types from Ace for this (still, do any from HF work for any part of this?  As luck would have it, I was using a wire-attachment on mine to brush-finish a 12" bar a couple nights ago and my die-grinder died, I've got HF's 2yr warranty so going to see how well they honor it although I've had their $10 angle grinders break and it's just needing another 'brush' piece installed) 

 

My fear, and it's big as hell, is I've never opened an engine block / moved piston/cylinder/shaft/etc relative to each other and it scares the hell outta me that I'll somehow ruin something.... or are you saying I can do this with the piston in there / at the bottom?  If I could just seal it off (am pretty confident in ability to do so) then it should just be grind, vacuum and un-seal... Re "piston skirt height // exhaust-outlet-height", wow I'd never have thought of that thank you!!!  Yeah that'd be helpful to not make the port taller than the skirt, problem here is how on earth do I measure my piston's skirt?  Or the port for that matter?  I guess ditch real rulers and just use "~7/8th's of this chisel's tip" type measurements til I'm sure the port isn't too wide?  Am sure I could do it w/o fail if I was cautious enough!  I can't help but wonder if it's a tiny lil piston (25.4cc!) skirt which is why there's a wall created there in the 1st place!!

 

Thanks SO much for all of your help, have learned more from you in this thread than in so much youtubing/googling, it's very very appreciated man!!!

 

(PS- Since I see 200's referred to in your sig, I'd love to hear any lil soundbites you could toss me on that "chinese clone" (quotes may be unwarranted actually) 'Holzfformma G111' that's like $300 and supposedly fully-interchangeable w/ the 200t?  I'd never ditch my Scheppach csp2540 for small climbing saw but my 32cc/16" Tanaka isn't long for this world has a new problem each week it can seem and was eyeing echo 355's but if the g111 is basically a 200t for $300......are 200t's really a PITA to work on?  I'd think the sheer volume of data online would make them one of the easiest!!)

[ArborOdyssey]

On 15/02/2020 at 11:10, CutterSy said:

Well that was a lot to digest.
I’m not familiar with the models of saw you are modifying so it’s difficult to visualise, pictures would help.
If you want to dive down the rabbit hole of porting have a read of some of the links in this thread:

Chainsaw porting thread links | Outdoor Power Equipment Forum

OPEFORUM.COM

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Links to porting threads in one place. Please no banter there's plenty of places for that.Feel free to post your favorite...

‘How’ to mod a muffler depends on the design and what will fit under/ around covers etc. I usually either add a ‘pipe’ by brazing on a piece of steel tubing, or add a deflector by brazing on a formed piece of sheet steel. I generally either put big holes in or remove the baffle. There are no hard and fast rules, you just need to experiment and see what works for you. I find the more ported cylinders benefit from a more open muffler, but it’s all a balancing act. The more air/fuel that goes in, the more needs to get out (within reason)

Is brazing MIG, TIG or flux?  I'm so ignorant on welding but was badly looking for an excuse to get into it and think I've found one ;D

 

Will be tearing through threads there thank you, actually just signed up there recently so that's nice

 

Am quite happy with the two mufflers I did, the one on the 25cc Scheppach got WAYYY more opened-up than my 33cc Tanaka, kinda as-experiment, although it's the one w/ the restricted/mis-formed exhaust port so muffler mods shouldn't make an iota of difference (I keep thinking, "If that mal-formed port is blocking like 1/3+ of my exhaust, doesn't that mean my saw is performing at like 75%[if that] of what it should be?")

 

Since "this round" is done I figured to attach pics:

- scheppach's muffler, cat removed and center baffle majorly opened (3rd pic is to show how I had to re-plate the top, had to bore-through it to get more access to the center and just patched it when done -- of interest is that after a couple jobs with it, the Copper Permatex I'd used that'd squished-into the muffler, is still in great shape

 

Side-by-side w/ the Tanaka (lol yes I'm aware how ridiculous my air-intakes are, I'd been experimenting w/ goo's & fabrics/filters am embarrassed showing early works on that but so be it, next applications will be very clean ;D )

 

Tanaka's muffler, didn't open it up as much because I've yet to get the saw as-reliable as I'd like so don't want many extra-variables, the scheppach was bought new 8mo ago and has been nothing but reliable!

 

1 Large hole ^ for flow although the Cat was torn out as well as center-baffle having a corresponding hole, there's also a hole on the front/top not visible here

 

 

^majorly opened their entry-ports as OEM holes (on both!) were either restrictive or dead-equal which'd mean that any mis-alignment mounting them would restrict flow so I just made huge holes on both muffler's entry-ports, just leaving enough edging for some copper Permatex to make gaskets   Went back and removed both (one to inspect, the other because I needed access behind the muffler) and thankfully neither one had an iota of Perma get in-the-way of exhaust flow, guess my approach of "thick, but favoring the outer-perimeter" works a charm, at least when that perimeter is open & can take the squish-out ;D

 

 

[PS- Am curious how dangerous you guys would consider my hand-guards/chain-brake-levers?  They're strong enough that I pick my saws up by them lol but I hate not being able to see so tend to dog them out like that, I wouldn't do it on a ground saw but for mid-30cc's and under top-handled climb-saws I just see it as a worthwhile sacrifice, obviously a big shield there would be safest so it's all relative I mean I do still have *some* guarding ? ]

Edited February 28, 2020 by ArborOdyssey

[Stubby]

25 minutes ago, ArborOdyssey said:

Is brazing MIG, TIG or flux?  I'm so ignorant on welding but was badly looking for an excuse to get into it and think I've found one ;D

Brazing  is with a brass filler rod and some flux . It has a lower melting point than weld . MIG if I remember correctly is Metal Inert Gas and TIG is Tungsten Inert Gas .  

 

[spudulike]

I am thinking Mendiplogs has moved to the US!

[peatff]

What's the point of the skeleton chain brake lever ? I have never found myself in a position where the lever has caused me any problem with visibility ? In a commercial set up they would be frowned upon but whatever floats your boat. I suppose they will still function till they break.