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Thinking about modding a MS 361

Ax-man

Ax-man

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Thanks, today should be the big day to see if this project saw will fire and run . I should have had it done by now but in addition to the engine I had to mix and match and fix other Mickey Mouse parts like the clutch and rewind and hopefully the carb I picked is a good one without having to get into taking that apart and screwing around with screens and diaphrams.
 
Yotaismygame

Yotaismygame

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Looks like it'll be an improvement. No poking fun of someones work who is just trying it out and brave enough to post about it. Check out my youtube channel in my sig. I have some porting videos that should give you plenty of incite.
 
Ax-man

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Thanks , I'll check it out. I have another piston and cylinder to work on . I'm surprised I didn't run into your vids when I was searching around U tube.

The saw I am working on is a runner . I like what I hear so far the saw has a good steady idle, nice smooth peppy acceleration ,bottom end sounds good, no air leaks, carb seems to be good and adequate to feed the engine. The compression came out a little low but not bad for a Frankenstine saw with used parts . The high end is just a shade under 14,000 thou. I pulled the limiter caps but I hardly had to do any carb adjustments save for the idle and a little on the L.

I did a few test cuts with that stock muffler on it and it did good , a little weak because of the compression but it didn't fall on it's face and went right through that test log without a stumble . I got some new rings coming that should boost the compression. Looking forward to doing some muffler mods and I think it will be a whole different saw. I am just happy that the darn thing runs and didn't eat a ring or blow up in my face. .
 
Yotaismygame

Yotaismygame

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I've seen plenty of OEM top ends with little to no beveling. I think beveling is a little blown out of proportion. But as easy as it is to do i'll continue to put a good bevel on cylinders that come through my garage. Majority of my videos have 50 or less views lol. I should probably put some tags on them. Did you raise the exhaust at all? If you did without doing a gasket delete or one at the least you'll lose compression. Higher exhuast=less trapped air in the combustion chamber=less compression. If you want to take it another step I do machine work for pretty cheap. Just like helping others out who don't have that ability.
 
Ax-man

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Don't feel bad about views . It is quality and savvy tech info that I am looking for. I did a three part vid on U tube about cutting down a leaning Red Oak tree. That was at least 8 years ago. I linked it for viewing on another pro tree site . Lackluster responses from the pro guys over there and I didn't get hardly any views or comments from the non tree crowd. I recently checked it for kicks and nothing has happened much since I posted it up on the tube. I guess I am not a good presenter entertainer type of person or I just turn people off . I dunno but my vid days are over even though I get tempted every now and then to put one up.

I didn't change any timing numbers on the exhaust or intake and stuck with a base gasket . What your saying is about the same thing the other good builders say that I trust to be true because it makes sense. I checked the squish without the base gasket and could tell right away it was tight , too tight like .017 and didn't want to take a chance on a big screw up . I maybe should have actually measured the ring gap on those rings but it looked good enough to me by eye. Who ever had this saw was not kind to it because the clutch was beat pretty bad so it stands to reason that the rest of the saw was worked hard and some how stayed together.

I going to give you some views later on tonight .
 
Ax-man

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Around .025 to .030. Measuring squish is new to me . I found out it depends on where you measure the solder and how you place the solder in the cylinder. The numbers aren't always the same. There close just have to come up with an average number. All I know is that it was much harder to squish the solder without the base gasket and it was just too tight for my liking.

I never had much luck at deleting base gaskets in the past but I also wasn't using the sealers we have today . All these part saws had one thing in common . They all had leaking base gaskets in the location where the base of the cylinder is the thinnest around the area of the lower transfers. That made me gun shy about deleting the base gasket.
 
Yotaismygame

Yotaismygame

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Oh I'm not worried about youtube. Wasn't until recent that I started talking. Before it was just to put saw videos out and eventually it turned into my resume as a builder. But now after tons of hours of research and personal experience I want to help out others who are interested in porting. .017 is just fine.
 
Ketchup

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I agree that 0.017” will be fine. Doing a delete isn’t as bad as you might think. Just make sure your surfaces are super clean and apply the liquid gasket very thin. I like 3-bond 1184 because it cures slower. I let an assembled delete saw sit for 12-24 hrs in a warm spot before pressure testing.

If you really don’t want to go with a full delete try to find an ultra thin gasket material that you can trace the oem gasket onto and cut out. The classic one is the aluminum wall of a beer can (usually around 0.005” thick.). Thin manilla file folder also works. Personally I find fabricating gaskets to be more work than deleting them. Obviously an appropriate base cut and oem gasket is better still.

It’s definitely worth it to get that squish down around 0.018”. It noticeably improves torque.
 
Ax-man

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Thanks , I'll give the manilla file holder a try . I think the reason I failed in the past with the full base gasket delete was because I really didn't give the sealer enough time to set . After that I tried a greeting card paper gasket and that worked on the 026 's I was trying to hop up. I'm after torque and I can live with .017 to .020 squish . I am going to be taking this saw apart anyway for the new rings so I'll go all the way and see what happens with a thinner base gasket.

Yotaismygame , I watched most of your porting vids you did very nice job on the presentation. Lots of good hands on info . I wished I had watched them before I got into this saw . I would have saved time if I used your method . I have just about all the right tools and bits except for a right angle grinder . I just went about the porting a little wrong but after seeing how you do it, would have been mush easier to widen, bevel and polish the ports . I did widen the intake port on this cylinder after seeing your pictures upstairs in the Husky you did . I had a pic but deleted it because I roughed up the roof of the intake port based on what old Iron+++++ was doing to his ports to help the fuel mix stay in suspension. The details showed up in the camera and just didn't want to get flamed for that one. I didn't cut any MM ear finger ports in the roof of the intake because that didn't make sense to me but I figured a few ridges aren't going to hurt anything but just wanted to see if would make a difference which it didn't. I have seen this debate in the past on this site about how to keep fuel mix in suspension. One guy says one thing and another argues the opposite and you don't know who is right.

I watched a few of your ported saw vids and I like what I hear . You do nice work and I bet you file a mean chain .

Oh, I like your lathe also . I need a new toy to search for . I have a wood lathe so I won't be completely in the dark if I ever find one
 
Ax-man

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Wow, that is a terrible . How the heck did Stihl stuff all that in there. I would open up the muffler I have but I need it for that other saw I will probably end up selling . I would rather practice a serious muffler mod on an aftermarket muffler . I changed the mufflers around today and I could tell that stock muffler was not only blocking that enlarged exhaust port I made but also wasn't letting the spent charge get out of the exit hole that is already there. Now I can see why. Thanks for the pic at least I know what I am in for when the time comes.
 
Ax-man

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My aftermarket mufflers came in . They are stuffed up just like the oem muffler. What is the best way to get them apart ??? Undo that crimped seam ??? I don't really want to cut it open with some type of cut off wheel because then I would have to weld it back together somehow and it probably won't line back up to put it on .
 
Ax-man

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Thanks , that was helpful . I don't have a mig welder . I have an arc welder but that isn't going to work on that thin metal . I could braze it back together but that is also a lot of heat for that thin metal and probably look ugly .
How about soldering back it together ?? I don't know hot a muffler is going to get but I don't think it will get hot enough to turn the solder into mush .
 
Yotaismygame

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I use a mig on my mufflers. Generally isn’t an issue. But a tig would be better. I’ve never brazed but people do.
 
Ketchup

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Here's everything that's going on inside your 361 muffler. This is the worst flowing non-cat muffler I've been into. I think it would really hold back any other mods you've done. View attachment 801784
Never fooled with a 361 muffler, but judging by this, I would try hogging out the #1 area as much as possible, then put a new outlet and deflector on the flywheel side (if there’s room). I hate cutting mufflers open and putting them back together.
 
cuinrearview

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Never fooled with a 361 muffler, but judging by this, I would try hogging out the #1 area as much as possible, then put a new outlet and deflector on the flywheel side (if there’s room). I hate cutting mufflers open and putting them back together.
I don't mind deconstructing them, and I have a guy that loves buttoning them up. It was only four spot welds that held the whole mess in there so it's all gone. I'm expecting a nice gain just from that, but I also went the dual port route.
20200305_060926.jpg
 
Ax-man

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That looks good . I am planning on doing the same . I got the muffler gutted . I tried to uncrimp it but that didn't work out so good. I tried to grind off that folded edge or crimp around the muffler that didn't work out either . I finally just took the cut off wheel on my grinder and opened it up by slicing it to make two halves . I am going to try and solder it back together when I get to that point. This is the most involved muffler mod I have gotten into . I just had to go and pick a ms 361 to do an actual porting job and major muffler mod . This is just getting more and more involved than I thought it would be . The guys who do this sort of thing to make money earn every penny . This has been an eye opening project .

I appreciate the help you guys are giving me .
 
cuinrearview

cuinrearview

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That looks good . I am planning on doing the same . I got the muffler gutted . I tried to uncrimp it but that didn't work out so good. I tried to grind off that folded edge or crimp around the muffler that didn't work out either . I finally just took the cut off wheel on my grinder and opened it up by slicing it to make two halves . I am going to try and solder it back together when I get to that point. This is the most involved muffler mod I have gotten into . I just had to go and pick a ms 361 to do an actual porting job and major muffler mod . This is just getting more and more involved than I thought it would be . The guys who do this sort of thing to make money earn every penny . This has been an eye opening project .

I appreciate the help you guys are giving me .
I have access to a big vertical belt sander that makes quick work of that seam. All that's left is the two halves and a thin ring of steel. Pull the spark screen and drill out the four spot welds and the whole mess comes out. Easy peasy. The 361 likes muffler in the pic above.
 
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