084 porting ?'s

[thomas1]

I picked up an 084 project that has had some grinding done on the ports. I have only pulled the muffler so far, I will update the thread as I get further into the tear down.

The second pic is with me holding the exhaust gasket even with the top of the exhaust port. Notice how the port extends below the bottom edge of the gasket? The muffler inlet is the same size as the gasket. It would seem to me that having an 1/8" lip created by the muffler would not be optimal for flow.

Am I better off to open the muffler inlet or, start the hunt for another cylinder?

I'm planning to use the saw mostly for milling, if that matters.

I can't wait to see what's waiting for me inside the cylinder.

 

[BiodieselNC]

You are correct, it will hinder flow if the muffler opening is significantly smaller than the exhaust port on the cylinder. I usually enlarge the exhaust outlet a little, although I probably would not have gone quite as large as you did. I always port-match the muffler to the cylinder, and you can use the exhaust gasket to make a template that you then trace onto the muffler. Keep in mind the 084 muffler has a cage, so this will somewhat limit how large you can make the opening. Also keep in mind that 084 mufflers are no longer available, so be careful with it!

While you're inside the muffler, go ahead and drill a bunch of holes in the cage, or cut it out entirely. Anything you can do to open up the muffler some will help. Those saws are 122cc and take deep breaths.

 

[thomas1]

You are correct, it will hinder flow if the muffler opening is significantly smaller than the exhaust port on the cylinder. I usually enlarge the exhaust outlet a little, although I probably would not have gone quite as large as you did. I always port-match the muffler to the cylinder, and you can use the exhaust gasket to make a template that you then trace onto the muffler. Keep in mind the 084 muffler has a cage, so this will somewhat limit how large you can make the opening. Also keep in mind that 084 mufflers are no longer available, so be careful with it!

While you're inside the muffler, go ahead and drill a bunch of holes in the cage, or cut it out entirely. Anything you can do to open up the muffler some will help. Those saws are 122cc and take deep breaths.

The grinding was done by the previous owner. I guess I really need to pull the cylinder to see if the "bigger is better" theory was applied everywhere.

The unavailability of the 084 mufflers is why I am leery of hogging this one out. I already need to fix the modified outlet. There was no cage in this muffler when I got it, just a horizontal plate with a couple holes. The plate level is just under the exhaust outlet.

 

[BiodieselNC]

I don't know what to tell you on the muffler. I would say try and open her up a little bit, going slow, taking your time. The old saying, "its easier to remove more metal than put it back" applies here. Or you could leave it alone. I will say this, an 084 muffler can probably had for cheaper than an 084 jug.

If you got any pictures of your muffler, this might be helpful. From experience, if you can remove the cage, its a lot easier to open up the port. Here is a picture of my 084 muffler prior to opening up the cage. I haven't ported mine yet, as I have been trying to practice up on less risky saws. One day it will get ported. For now i have left the exhaust opening stock-sized.

View attachment 226306

 

[xtremez]

I don't know what to tell you on the muffler. I would say try and open her up a little bit, going slow, taking your time. The old saying, "its easier to remove more metal than put it back" applies here. Or you could leave it alone. I will say this, an 084 muffler can probably had for cheaper than an 084 jug.

If you got any pictures of your muffler, this might be helpful. From experience, if you can remove the cage, its a lot easier to open up the port. Here is a picture of my 084 muffler prior to opening up the cage. I haven't ported mine yet, as I have been trying to practice up on less risky saws. One day it will get ported. For now i have left the exhaust opening stock-sized.

View attachment 226306

Wow, my 084 muffler looks completely different and its not modified at all.

 

[blsnelling]

There are a few different 084 mufflers.

 

[xtremez]

There are a few different 084 mufflers.

Good to know

 

[thomas1]

Pulled the cylinder:

Transfers

Intake

Any reason to leave that big hump in the intake port?

The port edges don't looked have been messed with to much, I am thinking of trying to smooth out the current golf ball texture and see how it goes.

Unless, somebody is getting ready to hog out a stock 084 cylinder and thinks they wanna swap for this one?

 

[Jacob J.]

If I were you, I'd just smooth everything out and leave the muffler stock and be happy with it. The exhaust gasket doesn't line up with the
top of the exhaust outlet stock. It's the holes that line up, even on a stock cylinder. Yes, the smaller muffler opening will hinder flow some
but it looks like to me that cylinder isn't going to make the best running saw anyway, depending on how much the exhaust has been opened up.

 

[blsnelling]

Someone was mighty sloppy with their grinding! Looks like they removed the little tongue that hangs down from the top of the intake port to keep the rings tucked in. The rest looks like it can be cleaned up.

 

[pioneerguy600]

That`s a pretty rough port job, worst is there does not look like there is any bevel at all on the cylinder edge of that grinding, it don`t need much but none at all leaves ragged edges that will scrape away at the piston. Intake and lower transfers just need to be relieved with a rubbing over with a piece of 250 grit black machine paper to take off the rough edges. The exhaust port and upper transfers can get by with a .010 bevel to prevent ring snagging.

 

[Dennis Cahoon]

Thomas......all that porting can be straightened out real easy. The intake tonsil is gone, but that's how a racing cylinder is ported. What you do is run 1 ring, but I if you keep the same port size(racing intake is much larger) you shouldn't have a problem catching the bottom ring. Get rid of the lip. Clean the rest of the nicisil off the bottom tranfers and match it up to the inside edge of the cylinder. Smooth up the transistion and you'll be good to go. Same with the exhaust, just smooth it out and match it to the muffler.

 

[thomas1]

If I were you, I'd just smooth everything out and leave the muffler stock and be happy with it. The exhaust gasket doesn't line up with the
top of the exhaust outlet stock. It's the holes that line up, even on a stock cylinder. Yes, the smaller muffler opening will hinder flow some
but it looks like to me that cylinder isn't going to make the best running saw anyway, depending on how much the exhaust has been opened up.

Jj, I was just trying to illustrate how much the gasket/muffler was going to shroud the exhaust port.

There's going to be at least an 1/8" difference all around.

 

[Scooterbum]

Jj, I was just trying to illustrate how much the gasket/muffler was going to shroud the exhaust port.

There's going to be at least an 1/8" difference all around.

Just make a new gasket to match the cylinder and open the muffler to match.

Looks like they ported it with a right angle grinder........

 

[thomas1]

Ok, I plan to smooth this mess out and bevel the edges. We'll see how bad I screw that up before messing with the muffler.

Any reason to leave the big hump in the intake port?

Thanks to everyone for their input.

 

[Jacob J.]

Ok, I plan to smooth this mess out and bevel the edges. We'll see how bad I screw that up before messing with the muffler.

Any reason to leave the big hump in the intake port?

Thanks to everyone for their input.

Before you go messing with the muffler, you may want to think about how you're going to go about that.
I've seen people grind the flange off inside to match a larger exhaust outlet and then put the saw into service.
Then the vibrations from running the saw in normal operations causes the newly modified muffler to crack
where it contacts the exhaust lip. If you're going to grind that flange out, think about welding a supporting
piece on there to strengthen it. As mentioned above, these mufflers are NLA and it's getting really tough to
find them now. The last new one on ebay got almost $300.

 

[Dennis Cahoon]

Any reason to leave the big hump in the intake port?

No!......I already said "get rid of the lip". You must of missed it.

 

[nmurph]

The intake tonsil is gone..

DC, just picking at you, but that part would be analogus to the Uvula, not tonsils. Your tonsils, assuming you still have them, are in the corner of your throat. Your Uvula hangs down in the back of your throat.

Looks like they ported it with a right angle grinder........

It looks to me like Fred Flinstone used an rock axe...

No!......I already said "get rid of the lip". You must of missed it.

He thought you said get rid of the lisp...

Thomas, it sounds like you might have a runner here is spite of the PO's ham-fisted attempt at porting.

 

[thomas1]

Before you go messing with the muffler, you may want to think about how you're going to go about that.
I've seen people grind the flange off inside to match a larger exhaust outlet and then put the saw into service.
Then the vibrations from running the saw in normal operations causes the newly modified muffler to crack
where it contacts the exhaust lip. If you're going to grind that flange out, think about welding a supporting
piece on there to strengthen it. As mentioned above, these mufflers are NLA and it's getting really tough to
find them now. The last new one on ebay got almost $300.

Jj, everything you said is exactly why I am leery of butchering the muffler to match the butchered cylinder.

Maybe I should just send it to Dennis and have him build a pipe?

 

[thomas1]

No!......I already said "get rid of the lip". You must of missed it.

I thought you were talking about the exhaust/muffler, when you said lip.

Got any unwanted 084 pipes laying around?