Homelite 150 piston ring question with picture

[struggle]

Those of you that have been helping with his I have some questions. I removed the piston out of the saw I have and found the rings to look dark and also noticed the rings still have (rings) in the wear surface. Tonight I tried reinstalling the piston and had no issue with it sliding in after I lined up the pins.

So after knowing it was not difficult to reinstall the piston I took the one out of the donor saw that a AS member sent to me for the use of the fuel tank.

Here in the picture is the difference in the rings. I am thinking that my saw has had new rings installed and that is why maybe that compression was on the low side (90 psi)? As they were not worn in yet. This saw came to me in parts so I do not know the history on it. It was quite clean as in cleaned for a repair but case was broken and tank leaked fuel.

Does this one ring look like it would if it were new> the cylinder on the inside is smooth.

I am thinking the possible reason for the saw running so poorly was the crank seals are hard as rocks and it was not pulling fuel properly? Just trying to figure out what way to go with this.

It seems to me there is nothing wrong with the rings as they look new and not run beyond me starting a last week.

 

[stinkbait]

I would say that the ring on the right looks like it has little to no wear, but I may be wrong.

One thing that you could do is install both rings in the cylinder without the piston and compare the ring gaps.

 

[galde]

The easiest way to gauge a ring's wear is to insert the ring into the bore and use the piston skirt to push the ring squarely to an area above the exhaust port. Take care to locate the ring end gap where the pins in the ring groove would place it. Use a feeler gauge to measure the end gap. Some older saws did not have ring-indexing pins in the ring grooves, but most saws have the pins. The end gap in the ring should only be large enough to accomodate the pin plus 5 or so thousandths of an inch to allow for thermal expansion. If your new-looking ring is a proper fit in your bore, you can gauge the worn one against it. You have the older squared ring ends, but most newer rings have a wrap-around end shape to go around the pin. Excessive ring end gap will reduce compression even in an otherwise perfect bore.

 

[struggle]

The easiest way to gauge a ring's wear is to insert the ring into the bore and use the piston skirt to push the ring squarely to an area above the exhaust port. Take care to locate the ring end gap where the pins in the ring groove would place it. Use a feeler gauge to measure the end gap. Some older saws did not have ring-indexing pins in the ring grooves, but most saws have the pins. The end gap in the ring should only be large enough to accomodate the pin plus 5 or so thousandths of an inch to allow for thermal expansion. If your new-looking ring is a proper fit in your bore, you can gauge the worn one against it. You have the older squared ring ends, but most newer rings have a wrap-around end shape to go around the pin. Excessive ring end gap will reduce compression even in an otherwise perfect bore.

This is what I was wanting to know. That seems like a very good explanation. I will check that out. I do not want to put the thing back together and seal it all up without really knowing if I should have put new rings in it or not. I just want to see it run properly.

I am thinking of making a vacuum block set up as well to check that after it is all back together. Once I get this ring thing figured out.

 

[67L36Driver]

I would say that the ring on the right looks like it has little to no wear, but I may be wrong.

One thing that you could do is install both rings in the cylinder without the piston and compare the ring gaps.

Yup, new one on right in pic.

 

[struggle]

I put the old and new ring in the cylinder but could only check by eye as my feeler guages are angled for setting valves I was not able to measure the distance. I can only tell the the newer looking rings spring out much further than the worn ones from sitting on the desk. I could not see any real difference while inside cyclinder.

I looked for new rings on line but could not find anything under the original part# other than NLA

I think I am going to try and reinstall them with new crank deals and run the saw for a while and see if it improves.

I cannot see if there is a topside to the rings or down side. Should I see a difffernce on the ring itself. Looks to me that they can go ether way.

I am guessing this saw has not run with these rings other than when I started it. As they look to have no wear to me, compared to the other ones.

I am still waiting on the NOS crank seals to show up

 

[a. palmer jr.]

It might pay to slightly roughen up the cylinder bore before you assemble it so the ring will seat in. I would do that slightly even if it is a chrome bore, just don't go overboard. On something like that I usually just use some sandpaper, maybe 300 grit. Be sure you clean it afterward and oil it prior to assembly.

 

[a. palmer jr.]

I put the old and new ring in the cylinder but could only check by eye as my feeler guages are angled for setting valves I was not able to measure the distance. I can only tell the the newer looking rings spring out much further than the worn ones from sitting on the desk. I could not see any real difference while inside cyclinder.

I looked for new rings on line but could not find anything under the original part# other than NLA

I think I am going to try and reinstall them with new crank deals and run the saw for a while and see if it improves.

I cannot see if there is a topside to the rings or down side. Should I see a difffernce on the ring itself. Looks to me that they can go ether way.

I am guessing this saw has not run with these rings other than when I started it. As they look to have no wear to me, compared to the other ones.

I am still waiting on the NOS crank seals to show up

A lot of the old saws have parts that are numbered "NLA". Just kidding..

 

[struggle]

No hone here. I will go with a light sanding and clean and lube.

I am half wondering how accurate my psi Gage is now. After I think about it I bet it is 20+ years old.

How long does it typically take to seat new rings on a small saw?

Can a cylinder be scuffed with 00 steel wool or is that big no?

 

[a. palmer jr.]

It could probably be scuffed with steel wool, but remember you're just taking the glaze off the cylinder, not trying to remove any of the chrome or metal. Just lightly scuff it so the rings will seat better. Chrome, if that's what it is, actually keeps the rings from seating easily compared to cast iron. That might account for it having new rings and still having low compression. It may have just needed a few more "miles" on it to break it in.

 

[67L36Driver]

I put the old and new ring in the cylinder but could only check by eye as my feeler guages are angled for setting valves I was not able to measure the distance. I can only tell the the newer looking rings spring out much further than the worn ones from sitting on the desk. I could not see any real difference while inside cyclinder.

That is good. The old ones have taken a set due to temperature and age.

Use the 'newer looking' rings.

 

[a. palmer jr.]

No hone here. I will go with a light sanding and clean and lube.

I am half wondering how accurate my psi Gage is now. After I think about it I bet it is 20+ years old.

How long does it typically take to seat new rings on a small saw?

Can a cylinder be scuffed with 00 steel wool or is that big no?

Just in case you didn't know...best to go around the cylinder(crosswise) while scuffing, not up and down in the cylinder.

 

[struggle]

Well here it is in action. I finished it this afternoon. IT seems to be running good I guess. I have never run one of these and only have the 019T to compare it to, which certainly is a better saw I would thank than this one ever was.

I am aware of cutting over the driveway not a good idea. This thing seems loud to me as well. I guess that is the way they were back then.

Compression checked at 100 after it cooled off a bit. I am going to have to check another gauge against mine. I still find it hard to believe that it will turn this size bar buried in a tree.

Oil pump worked works good. I see there was a running change in the pumps as this one has a feed from the pump via the case where the other block feeds off the pump into hose at bar location.
[video=youtube;OySyOwqC-EM]http://www.youtube.com/watch?v=OySyOwqC-EM[/video]

 

[kev1n]

Great job getting it back up and running. It looks like it's running great! I think your compression gauge is a little worn out. Did you try your gauge on your 019T or another good working motor? I think you can replace the schraeder valve in those. You could take your saw over to autozone for a compression reading.
Good job sticking with it and getting it finished.
Kevin

 

[a. palmer jr.]

You might also give it a little more running time so it'll be broke in more. Compression might be higher later on. One thing people don't think of and that is the kind of oil you use in it and what ratio you use, it might affect the compression also. Great job of getting the saw back together, I'll rep you if I can. Well, I tried and it says I'll have to wait before I rep you again.

 

[struggle]

I pulled the plug on the 019T and it pulled cold 110 psi and it runs great. So it is safe to say my gauge is not reading to accurate. Crapsman gauge although it is 20+ years old.

I am going to run several tanks of fuel through this saw before it goes to the neighbor. I would like to see the rings break in.

I am kind of getting attached to it. I must make sure it is ready before it gets adopted.

Next on the block will be a homie 360opcorn:

Thanks for the positive comments. I know it really is not much of a saw but a good place to start.

Also I am running 40:1 quaker state oil. I am going to move up to Stihl synthetic for next oil.