Question about replacing rings

[Ryan Browne]

So, I've got a good running saw and I stumbled across a used OEM cylinder in decent condition. I'm gonna try my first ever attempt at messing with the ports with my burr grinder. My question is: after grinding and shining, etc, can I just install it on my saw, or do I need new rings?

I guess many of you already know this, but I'm new at this .

Thanks

 

[BigRed96]

So, I've got a good running saw and I stumbled across a used OEM cylinder in decent condition. I'm gonna try my first ever attempt at messing with the ports with my burr grinder. My question is: after grinding and shining, etc, can I just install it on my saw, or do I need new rings?

I guess many of you already know this, but I'm new at this .

Thanks

If it was me I would replace the rings. Something like $15 for a set of Cabers.

 

[cus_deluxe]

Yep, i would scotchbrite that cylinder and put new ring/rings in onto it. Probably more important than the ring/rings in this case though is to make sure ports are nicely beveled.

 

[Landmark]

Used piston is ok but used rings.....

 

[Red97]

If ya have it apart might as well do it. Without a nice bevel you will he doing it sooner than later.

 

[old guy]

Put the ring in the cyl. and push it down with the piston to just above the intake port, measure the end gap with feeler gauges, new rings will be .008 -.010 or so. I put one back in that was .014, replaced a couple that were .018 to .020. My 372 picked up 6 lbs. of comp after one start up with the new rings.

 

[mdavlee]

Depends on how used the piston is. If it's blowing 175 psi I'd just reuse them and not have to break them in again. How wore is the skirt?

 

[Ryan Browne]

Thanks guys. I tried googling it. Normally I'm pretty good at that (better than working on engines anyways), but honestly couldn't find the answer.

Now I know. Super cool to be able to learn this stuff.

 

[Al Smith]

I've done it both ways,new or use the old .Keep in mind often on a used cylinder it will take some time for the new rings to fully seat .Not to worry unless it's out of round like a football they will .

 

[smokey7]

If you are grinding in the port window be sure to know what you are moving and why. Lots of things to watch for. Like ring end gap/locating pins, skirt edges,freeporting, and shape, To be just grinding away at stuff. Just remember sometines a little is alot, and start slowly using alot of check cut a little check and check against a degree wheel and card stock as a stopper to cut to. So much to it to, just be careful, and ask questions. As far as ring reuse a measurement or damage will guide you on that call.

Ps not trying to be a Richard Cranium just trying to help.

 

[Ryan Browne]

Depends on how used the piston is. If it's blowing 175 psi I'd just reuse them and not have to break them in again. How wore is the skirt?

I haven't pulled the jug yet, so I don't know the ring end gap, or the condition of the piston skirt. Honestly, even once I pull out I won't know what to look for on the skirt. I do know how to check the ring end gap, and to do it in several places along the bore.

I don't even have a compression gauge, but maybe I will on the near future. The rope pulling compression gauge tells me that the saw has good compression, but I know that isn't good for much.

My thought was to do a very very conservative port massage on the new jug that i got, before installing it. I'm thinking about just slightly widening the intake and exhaust and squaring up the corners. Nothing crazy. Then pull the jug, throw the new one on and see what's different. If nothing else, it'll be a pretty cheap learning opportunity.

It looks like a set of cabers is only like $11 after shipping. It looks like I'll probably be in this thing a few times, so I'll reuse them until I think I've got things where I want them and then maybe throw in a new set.

 

[Redfin]

Put the ring in the cyl. and push it down with the piston to just above the intake port, measure the end gap with feeler gauges, new rings will be .008 -.010 or so. I put one back in that was .014, replaced a couple that were .018 to .020. My 372 picked up 6 lbs. of comp after one start up with the new rings.

Ive had a brand new set of Stihl rings for an 046 gap at .016". Replaced with Cabers at .008".

Point, check gap. If old rings are in spec Id run them.

Edit: If you do plan on running the exsisting rings and there are two, make sure they are put back in the same land.

 

[Ryan Browne]

If you are grinding in the port window be sure to know what you are moving and why. Lots of things to watch for. Like ring end gap/locating pins, skirt edges,freeporting, and shape, To be just grinding away at stuff. Just remember sometines a little is alot, and start slowly using alot of check cut a little check and check against a degree wheel and card stock as a stopper to cut to. So much to it to, just be careful, and ask questions. As far as ring reuse a measurement or damage will guide you on that call.

Ps not trying to be a Richard Cranium just trying to help.

Thanks for the input!!

You aren't coming across as a dick head at all. I understand that I comprehend about 1% of the knowledge a professional builder has at his fingertips. Maybe less. I'm thinking that since I've got two OEM jugs, that I'll try playing around with one of them.

I'm thinking for my first attempt, I'm just gonna widen the ports and clean up a couple little boogers in transfers. I won't raise the ceiling or lower the floor of anything yet. Once I get the new jug installed and tried out, I'll put a degree wheel on and see what changes might be possible.

The more I read I feel like the less I know, but I've been reading a lot on here. I have a super basic idea of what the port shapes should be, and I know about the need for bevels. I also know to be very conservative, and when in doubt to leave stuff alone.

THANKS everyone for your patience and for all the helpful contributions!

 

[smokey7]

Thanks for the input!!

You aren't coming across as a dick head at all. I understand that I comprehend about 1% of the knowledge a professional builder has at his fingertips. Maybe less. I'm thinking that since I've got two OEM jugs, that I'll try playing around with one of them.

I'm thinking for my first attempt, I'm just gonna widen the ports and clean up a couple little boogers in transfers. I won't raise the ceiling or lower the floor of anything yet. Once I get the new jug installed and tried out, I'll put a degree wheel on and see what changes might be possible.

The more I read I feel like the less I know, but I've been reading a lot on here. I have a super basic idea of what the port shapes should be, and I know about the need for bevels. I also know to be very conservative, and when in doubt to leave stuff alone.

THANKS everyone for your patience and for all the helpful contributions!

Very good you are in a perfect place to learn. Enjoy it and go cut some wood, maybe even cut with dad or your kids its a great time together.

 

[Ryan Browne]

Very good you are in a perfect place to learn. Enjoy it and go cut some wood, maybe even cut with dad or your kids its a great time together.

Thanks, smokey. I do love cutting wood, that much is for sure!! I wish I had more friends in the area that love it too. I get to cut with a couple of my neighbors every once in a while, but scheduling is tough. It'll get easier this winter.

Pops doesn't cut much these days. He still can, and hopefully he will this winter. My little girl can't run a saw quite yet, but she and I do a lot of stacking together. She likes to ride on my lap on the tractor when we're pulling the wood trailer around too.

Here's a picture of her on my round pile of wood this spring. They're both a little taller now.Gotta look close, but she's in there.


I think it's pretty swell to have a place like this to learn about saws. My dad isn't much of a mechanic, so I never grew up doing this stuff. I took the basic shop classes in high school, but I didn't get into tools and working with them until a few years ago. I've got a long long way to go, but I can handle basic repairs around the farm and simple things on my vehicles. This stuff all used to scare me, but slowly it's getting easier. And, I enjoy it. Thank heavens for the internet!

 

[smokey7]

Very cute little girl. I got my little 6 month old daughter she loves to hang out with me in my garage. I actually put her in a doorway jumper/bouncer that i hang from my engine hoist. As long as i dont make alot of noise she is good.