wanting to do muffler work to my ms361

c2500blue

what is the difference between a full woods port and just muffler mods

ScottWojo

With a muffler mod you get a significant increase in power with a low price.

With a woods port you will get beyond the power increase obtained with the Muffler mod.

But you get 20-25% with just the muffler mod. then with a woods port on top figure another 10-15% with conservative power gains.

With the woods port you must have the muffler modified to accept the woods ported cylinder.

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ScottWojo HP Modified Chainsaw Mufflers| GB Bar and Chain Distributor.

southsoundtree

What are the drawbacks to muffler mods and woods porting, if any, aside from the price?

Cut4fun

Well a muffler mod is a easy job on a 361 and no cost.

Woods porting can take you a few hours to a couple days (DEPENDING ON WHAT YOU DO TO IT) to get it right. Also can be done by yourself and for free.

If I want a fast woods port I call 911 of a good builder. If just a work saw where cut speed isnt a concern, do it yourself.


A good woods port will run you $200-$250 by a good builder (beware chitty builder out there to take your $$$) read learn ask in pm's who to avoid. Now there is some pretty crappy builders out there charging $250-$300. Buyer beware.

I have ran saws from builders from east - west , north - south. Some of the most hyped up builders are some of the poorest slowest saws I have seen.

windthrown

Woods porting typically includes a muffler mod, which is typically:
1) Muffler opened up or dual port cover added, and/or muffler gutted and/or the CAT removed and carb re-tuned richer
Additional 'woods' porting can be done in stages of complexity and stopped at any point, and some stages can be skipped:
2) Intake and exhaust ports opened up and polished, muffler opened up to match exhaust port
3) Cylinder base turned down and the outside of the piston crown turned down to increase compression (or the cylinder gasket thinned or removed)
4) Transfer ports opened up and/or polished, piston lightened/polished, port timing adjusted
5) Carb rejetted or swapped out with a bigger carb to allow for more fuel
6) A non-limited coil can be added if the saw has a coil RPM limiter

Gains vary. As said, there are come crappy ported saws out there.

windthrown

The drawbacks on a muffler mod and woods port are that they saw will typically burn fuel at a faster rate, and it will be louder. Muffler mods can be cheap though, and in many cases, can be done for virtually free. For example the Stihl 1127 muffler mod only requires some light drilling and carb tuning. The 440 and 460 muffler mod can be bought from Stihl for $35. Get the 460 DP muffler cover, and replace the stock cover with that, and retune the carb. Be advised that you need to correctly retune the carb after any mod to your saw, or the saw will run lean, it will overheat, and you will blow the motor. In the newer Stihl saws, that means removing the limiter caps and trimming the tabs, and replacing them in the saw. Then tuning it by ear and by a tach and doing test cuts to set the saw to run correctly.

Porting changes the torque and power curves, and if you are not careful with mechanical port timing, you can really mess up a saw's performance. You can get a saw that has good torque only at the low or high end. You can also over-port a saw in several ways. One is to open the exhaust port so wide that the ring gaps clip the side of the opened port and break the saw. Another way to overport a saw is to go beyond the tuning limits of the high speed jet of the carb. This will typically not damage the saw, but there is no point in porting to extremes if you do not get enough fuel mix in there to burn. You can also get screaming revs out of a ported saw, and the bearings and other parts are not designed for those speeds. So you have to port within reasonable limits. Generally woods ports are done on saws that are used every day. I lightly port my own saws with good results. Key word here is 'lightly'. Extreme porting can lead to weird and unexpected results, and generally the more you do, the more complicated things become.

stihl kickin

windthrown. when lightly porting your own. how much material do you remove?

windthrown

Um, depends on where the material is being removed from. I use emery paper on glass to take off all the gasket residue on the base of the cylinder, and then I sand off a few thou of an inch more to get a nice all-metal smooth base. I leave the piston pretty much alone, but I take off all the carbon, and gind off any casting crap under the skirts. If the rings are spongy, I put new rings on.

Then I mark off the exhaust port, noting where the ring gaps are on the piston. Stihls have 2 rings with gaps on either side of the exhaust port. I remove all the slag and casting crap in the port, and go out maybe 1mm on the sides and bottom of the exhaust port, keeping it oval. I leave the top of the port alone. Then I use a small smooth ball and lightly campher the inside of the port. On the outside of the port I take off more, between 1 and 2 mm all the way around, more or less squaring it up. Then I smooth it all out with a fine stone. Then I remove the same amount of material from the muffer gasket and muffler intake to match the outside of the exhaust port.

On the carb side it is a little different. I remove all the slag and casting crap in the intake port (sometimes it is really crappy in there), and I remove about 1 mm of material all around the port, (leaving the D shape on the 026). I leave that port rough, as a rough finish on the intake side helps mix the fuel better. I widen the port evenly front to back. I also campher the inside of the port with the small ball stone. If I am feeling like it, I angle the transfer ports back towards intake a little and taper the lower transfers toward the base of the cylinder.

stihl kickin

thanks for the info. i just bought a 026 with low compression and im gonna try porting and some muffler work. just a little winter project.

windthrown

I would slap in a pair of new rings first. Should make a huge difference.