55 Rancher porting or muffler mod

[GeorgiaVOL]

Since I have this Rancher apart I was wondering if any of you fine fellows have ported one or did avmuffler mod? So you have suggestions? Is it worth doing? I always wanted to try doing a port job. Didn't know if this was a good candidate.

 

[cus_deluxe]

A muffler mod on these is well worth doing, and usually the mufflers on these come right apart so its an easy mod. Ive done no porting myself, but i would guess some gains could be made by just widening and squaring ports, wothout changing timing.

 

[Stump Shot]

Yes, a very good candidate for your first time. Picked a 51 for my first. Easy to do a woods port on. Besides the muffler mod, check the squish and do a gasket delete if you can, also advance the timing a little bit and use a new air filter. These saws respond quite well to modification. Personally, I'm still just tickled right to the bone over the 51. Great little saws and easy to work on.

 

[GeorgiaVOL]

Is it worth it to get a couple of the cheap $20 chinese cylinders to practice on To determine a pattern for the port? Or will they run so different they won't give you acurate data

 

[Stump Shot]

Is it worth it to get a couple of the cheap $20 chinese cylinders to practice on To determine a pattern for the port? Or will they run so different they won't give you acurate data

I would have to say no to that. You really don't have to remove a lot of material for gains to be made. Stay well within the width of the piston skirt, take your time. You will start to see what you are trying to accomplish, then it's just execution at that point.

 

[Stump Shot]

I would also add there are plenty of threads on porting here to read. Also most of the good porters will try and help you out if asked a direct question.

 

[GeorgiaVOL]

Ok another question, I appologize if these are too basic, which of these examples are the more correct way to open the exhaust port?

 

[GeorgiaVOL]

I have been reading the part 1 thread. A lot of it I'm not sure what they are talking about. I will learn, just new to it right now.

 

[t4driller]

Ok another question, I appologize if these are too basic, which of these examples are the more correct way to open the exhaust port?View attachment 73180

In that pic, you just want to do the top right pic. Just widen if you aren't dropping the jug. You don't want to grind on the floor of the exhaust. Put the cylinder on it with piston in and take a sharp pencil and trace the exhaust port on the piston skirt. Will give you am idea how wide you can go. But for your first attempt I wouldn't push it to the limit. You have to have atleast 1mm of skirt covering the exhaust/intake ports. So don't go to wide.. I can text you some pics. Help better understand it.

Sent from my SM-G930V using Tapatalk

 

[GeorgiaVOL]

So this is what I'm dealing with. So I will widen the exhaust and bell shape the outlet. On the interior do you put a slight beveled edge on the exhaust port so it's not a sharp edge?

 

[GeorgiaVOL]

Cylinder pictures

 

[JT78]

You can go as wide as 70% of the piston bore looks like yours is the open port design (one without piston windows). I usually go about 65% to play it safe if it's a windowed piston you can go within .020 of the piston skirt on a work saw I sually keep it about .025 just to be safe.

 

[JT78]

And yes a little bevel will help.

 

[GoBigBlue1984]

Bump in timing will do about as much for these as widening ports from my experience. Others mileage may vary. I set squish anymore on 51/55 at .015. I just rebuilt one for my brother in law. New bearings, seals, gutted muffler. It's a pretty stout 55cc saw.

 

[GeorgiaVOL]

Thanks guys. My odds of success have gone up quite a bit today

 

[Chainsaw Jim]

You should start with a muffler mod and timing advance. That's where a majority of the gains will be had. If you're not satisfied with that improvement then look into getting a degree wheel and learning how to set it up before porting. You definitely don't want to mess with a port that's already in the right spot.

 

[GeorgiaVOL]

I haven't figured out how to change timing yet

 

[Chainsaw Jim]

You have to file about .020 off the side of the flywheel key that allows the flywheel to close that gap counter clockwise.

 

[GoBigBlue1984]

You should start with a muffler mod and timing advance. That's where a majority of the gains will be had. If you're not satisfied with that improvement then look into getting a degree wheel and learning how to set it up before porting. You definitely don't want to mess with a port that's already in the right spot.

Very sound advice!

 

[drf256]

Listen to Jim and Brett.

Widening that port's gonna give you that "feel good" feeling, but likely is just useless work.

Increasing the area of a port is gonna do nothing if you don't have more volume to flow through it. In fact, it will generally make things worse. You kinda want the smallest and tightest port possible to flow what you want at said RPM.

What's the squish without gasket?

Remember the 90/10 rule. 90% of gains are found in 10% of the work, and visa versa.

Unless you have access or are willing to have machine work done to the cylinder, and you can set up and use a degree wheel, just adjust your squish to 15-20. Use some sticky backed sandpaper on your piston crown to sand some out of the band if necessary to achieve your goal.

Advance the timing and muff mod the saw.

If you grind on any port, you'll need at least a small chamfer on the edge of what you ground or you'll chew your piston up. Been there, done that.

Remember that the OEM designed that cylinder through millions of dollars of research. Those ports are already in spots where the best compromise of power/fuel efficiency/durability is. When we play with the ports, we just pick one of these to trade with the other.

Sorry for the long winded response.