marred cylinder

[falconjet]

I've got a sachs dolmar 112 that locked-up. I dismantled the engine was able to get the piston out of the cylinder. The piston cleaned up real well. I have a new ring for it. The cylinder cleaned up well with 600 grit paper except for a small shallow vertical gauge just below the top of the ring travel. Probably no more than a few thousanths deep. I did not want to hone it out because I could not get a larger piston. Anyway, just wonder if this will cause a problem. I realize its a hard call without seeing it. Thanks

 

[Al Smith]

Correct about being a tough call ,however my suggestion.Put the ring on the piston and insert it in the cylinder and see if it hangs on the gouge.If it does not,reassemble the saw and give it a try.
You may want to use a little heavier gas/oil ratio.You really don't have much to lose,if you think about it.You might get lucky,some times one does.

 

[whatsnext]

I agree with Al's advice. You really have nothing to loose except a set of rings and a bit of your time. Just to give you some hope. I bought an Echo 25cc line trimmer that had seen so much use that the top ring just went away and left a bunch of deep scratches when it did. I just lightly sanded them out and replaced both rings. That trimmer still kicks butt. I think cylinders kind of self repair if the defects can fill with deposits faster than they re flame cut. A slightly oilier mixture may help fill the gaps.
John...

 

[bugfart]

Not to derail the thread, but while on the topic of rings; I have some 58mm and I'm wondering how much you can trim off without causing any grief? I believe these are for a Homie XP2000 and 2100. Could these be filed down for reliable use on a 1050 (55.5mm)?

 

[Al Smith]

Not to derail the thread, but while on the topic of rings; I have some 58mm and I'm wondering how much you can trim off without causing any grief? I believe these are for a Homie XP2000 and 2100. Could these be filed down for reliable use on a 1050 (55.5mm)?

Well I wish it was that simple.It may work but they wouldn't seal properly,until broken in which would take a long,long time.
If you do a "google" search on making piston rings,there are several sites that explains the process in detail .The design of piston rings for 2 cycle engines is slightly different from 4 cycle.The expansive forces are much less,for example.This plus the fact that because of ports etc,the 2 cycle rings are pinned makes them a whole different item to deal with.
Geometricaly speaking,you are trying to squeeze a big circle into a smaller circle.In the process of making rings,they are cut to the exact diameter of the cylinder then split and expanded on a mandrel,using heat to anneal,then retemper the metal.
What you could do is make a lapping cylinder and lap the rings to size.This however would entail much more work than just getting the correct sized rings.Give ole Bobs lawnmower repair,in Maryland New York a ring a ding,I'm about sure he would have the right ones.

 

[bugfart]

Thank you very much.

I had been all over the net reading about how people were performance tuning with trim to fit rings...

Maryland New York, that's a new low. I presume the state is New York and the stolen name for their city is Maryland?

"It's all the same joke!"
-Kevin Meany