Exactly how important is this step?

[WildnCrazyGuy]

- Position the piston ring so that its
ends meet at the fixing pin.

I was putting my FS36 trimmer back together and I don't recall doing this. Hopefully I did, or hopefully I got lucky, or when is it gonna break? Is it worth a breakdown and check or have I ruined it now anyway? Do I want to see the piston and cylinder at this point? Thanks.

Discovered this while preparing to do a MS290 rebuild. Got a parts saw with a good P/C and other stuff, waiting on my replacement parts now and was reading the shop manual and they made it sound real important, so I checked my FS36 shop manual and sure enough... Right there plain as day so hopefully I was reading pretty good that day, just don't remember specifically doing it.

I'll probably need some help on my MS290. First real project saw. All my others were just replacing fuel lines, misc. stuff like that. Thanks to all...

 

[Mad Professor]

You usually cannot get the cylinder on and/or break a ring if the pins are not aligned with the gap.

If by chance you got the jug on without breaking a ring bad things will happen if you run it, i.e. ring catches in port, ring breaks, piston breaks........

On some rings besides the gap there is also a up and down side.

 

[Erick]

I'd say you got it on right other wise you wouldn't have been able to get the jug on.

 

[WildnCrazyGuy]

You usually cannot get the cylinder on and/or break a ring if the pins are not aligned with the gap.

If by chance you got the jug on without breaking a ring bad things will happen if you run it, i.e. ring catches in port, ring breaks, piston breaks........

On some rings besides the gap there is also a up and down side.

Thanks for the info. Hopefully I did it right, but I'll probably tear it back down and see. Bugging the crap out of me right now. The FS36 is one of those that has a taper in the bottom of the cylinder that compresses the ring as you put it in. I had the page sitting right in front of me when I was putting it together, just don't fully recall that step and it seems like new news, like something I didn't know before if you know what I mean. It has run pretty good now for a few weeks, trims nicely, runs pretty smooth, for an old trimmer. Put a few bucks into it to get it back running after my piston rod failure, new gaskets, new filters, fuel lines, etc. so I probably need to set my mind at ease and pull it apart and see. Ho hum.

 

[Tzed250]

- Position the piston ring so that its
ends meet at the fixing pin.

I was putting my FS36 trimmer back together and I don't recall doing this. Hopefully I did, or hopefully I got lucky, or when is it gonna break? Is it worth a breakdown and check or have I ruined it now anyway? Do I want to see the piston and cylinder at this point? Thanks.

Discovered this while preparing to do a MS290 rebuild. Got a parts saw with a good P/C and other stuff, waiting on my replacement parts now and was reading the shop manual and they made it sound real important, so I checked my FS36 shop manual and sure enough... Right there plain as day so hopefully I was reading pretty good that day, just don't remember specifically doing it.

I'll probably need some help on my MS290. First real project saw. All my others were just replacing fuel lines, misc. stuff like that. Thanks to all...

Got The Stihl ring compressor for that model?

 

[Rookie1]

I'd say you got it on right other wise you wouldn't have been able to get the jug on.

:agree2:

 

[WildnCrazyGuy]

Got The Stihl ring compressor for that model?

You mean the MS290? I did get one ordered and delivered from my dealer. It was like $6 and change, but now I see I could have used a beer can. Maybe the tool will make things easier.

If you mean the FS36, the bottom of the cylinder tapers for the compression.

The FS36 smokes pretty good right now, but I chalked that one up to putting a new piston and ring in the cylinder and the ring needs to seat and then the smoke will clear a bit. Maybe it is seating... much to my dismay.

 

[huskydave]

You usually cannot get the cylinder on and/or break a ring if the pins are not aligned with the gap.

If by chance you got the jug on without breaking a ring bad things will happen if you run it, i.e. ring catches in port, ring breaks, piston breaks........

On some rings besides the gap there is also a up and down side.

Yes Sir but smetimes with small engines you need a certain ringgap let alone proper alignment. I remember having a ring crack on a two cyl snowmobile engine after forcing the rings around by hand (cut my fingers bad) and that was the last time I ever reused rings. My good engine needed a head and base gasket $2.00 and the $3.00 rings to me were unnessecary but I learned the hard way that time. Crack score bang bow quit. I now had a scored cyl a shot pisti
on and I still had to fix the snowmobile.