Spuds Porting and Tuning Thread

[Scott Walker]

Here we go, all fully ported saws that go out of my workshop will now bear a super duper ported label:thumbup:

 

It allegedly gives you 15% extra performance:001_rolleyes:

 

Gutted must of just missed my chance of one, I'll have to send you another 😉

[spudulike]

Gutted must of just missed my chance of one, I'll have to send you another 😉

 

They arrived today.....sorry.......what else have you got:lol:

[Scott Walker]

I'm sure I'll be sending you some more in the future Steve, plenty more saws in the garage for you to work your magic.

[Stubby]

Here we go, all fully ported saws that go out of my workshop will now bear a super duper ported label:thumbup:

 

It allegedly gives you 15% extra performance:001_rolleyes:

 

Hi Steve . Can I buy 3 from you . Only seems right and proper they should wear the " Emblem "

[spudulike]

Hi Steve . Can I buy 3 from you . Only seems right and proper they should wear the " Emblem "

 

You being serious Andy:001_tongue:

[neiln]

Hello, this saw modding is interesting, I've got a stihl ms180, Is muffler modding this worth the effort or just silly antics? The saw is small after all and is never going to be a beast, even with porting and all sorts of work…it’s a small saw! I own one to process my own firewood, its used on the ground for an hour or 2 at a time so its not about turning this into a lightweight beast that is fantastic up in a tree, but like anyone else…if I can get something for nothing (something worthwhile) that is good. If I could do a muffler mod, which would be zero cost and minimal effort, and gain enough power/speed increase to actually notice it cutting a little bit quicker, then I’m tempted. The saw is only 6 months old, I don’t want to risk killing it, and as I understand it these saws have unadjustable carbs, so if a muffler mod would cause it to run lean then I won’t risk it. Although if I can counter a slight risk by adding slightly more oil to my fuel mix (is that possible?) I’d do that. I live in suburban London, using the saw in my garden, so also need to think of the neighbours. I know a muffler mod would make the saw noisier but assume, since it’s a small saw after all, that it won’t make enough difference to annoy neighbours? I always use PPE including foresters helmet with ear defenders when I’m running it, so not so worried about deafening myself.

 

So, is a muffler mod to a MS180 going to make a noticeable difference to me, and if so…..how do I go about it? Is it as easy as removing the muffler from the saw, drilling a hole or 2 in the can to increase the exit hole area, and poking the drill inside the can and making holes in any baffles that can be reached? Total exit area wants to be about 80% of the cylinder exhaust port area yes? So I guess I don’t want to go very large, a couple of 10mm holes enough extra? Anybody done it?

[Stubby]

Just adding more oil does not actually compensate for it running " a bit lean " It just adds more oil ( there fore less petrol because more of the mix is made up from oil ) it wont stop there being more air flow because you have de restricted the saw to a degree with the MM . You need to keep the mix at 50:1 and adjust the carb so non adjustable carbs don't help . When you talk of lean and rich its fuel to air ratio not oil to petrol .

Edited February 17, 2016 by Stubby

[neiln]

Thanks stubby, yes i know lean or rich is air/fuel ratio, I thought the problem with lean adjustment of a carb though was less fuel mix also means less lube too, and hence risks scored pistons/cylinders etc. or is it leaning making the saw run hot? muffler mods are supposed to cool a saw aren't they?

 

anyway, i dont want to risk killing the saw if that is a real risk

[spudulike]

I have been porting a 372XP recently and had some interesting figures from the exercise. The saw was already wearing a jungle muffler which is basically an oversized 346XP exhaust so a large outlet on top and no internal baffle.

 

The saw, before any porting and wearing the performance muffler the saw gave cutting figures of between 13.36 and 14.48 seconds. After porting, using the same bar and chain the saw gave 11.10 to 11.48 seconds.

 

If you take the two best cuts pre and post porting, the improvement is 16.8% if you take the two worst figures pre and post, you get 20.56% improvement and if you take an average then you get 19% improvement.

 

The 372XP is a good machine to port and it shows that you gain 16-20% from JUST the porting. It would be interesting to see what the muffler gives and would suspect at least 15% so am pretty happy with that and it is nice to get some quantifiable figures on the table for reference.

 

We think that there may be a little more to be had from upping the max revs from 13500 to 14000rpm as it was loading up a little in the bottom of the cut but am very happy with where this has ended up.

[medroberts]

Steve, My 395xp arrived back on Friday at work, so Friday night I put the 24" bar and chain back on and went to start it as normal:blushing: Bl**dy hell there is some compression in it now:thumbup1:I can only start it with the decompressor in:thumbup: I have tried it this afternoon in 2ft piece of oak and cannot slow her down in the cut:lol: What rpm did the saw tach to ? Sounds nice ticking over with M/mod. Many thanks , I will let you know how she gets on , when this weather improves:001_rolleyes:

Med Roberts.