Ring installation

[wasmeneh]

Well I got my K321 broken down and the old rings off. Went to put on the new rings, Sten part # 500-744, and the oil control went on fine as did the second ring although it seemed to large even when compressed. The third, top ring, was to thick and after I ground it down it was also too large in circumferance to go back in the bore even when compressed. I had ordered the standard ring set from a guy who supplies rebuild kits on Ebay, I've emailed him but no reply yet. The piston looks OK just a few minor scuffs, the bore looks great. Any idea what I should do next? Mike

[Chris727]

Sounds like he sold you the wrong size. As for the one being to thick, maybe its defective. I've heard good and bad about aftermarket parts.

[papamerkle]

Mike, Is that the correct Stens number? I have to agree with Chris-you have the wrong rings for your motor. Did you check ring gaps before you installed rings on piston? Kohler has spec on what the high/low tolerance should be on end gap and groove. If you don't have on a Kohler manual you need one. Here is a manual you can download from Kohler: http://www.kohlerengines.com/pdf/tp-2379.pdf This manual will walk you the procedure on how to check end gap. My Son works in a repair shop that uses Stens. They have no problems with Stens. I use Kohler parts on Kohlers and Briggs parts on Briggs. Bad thing since you ground on top ring you may not get your money back or the right rings.

[wasmeneh]

That's the number off the box, bought the rings from a guy on Ebay and he has retuned my email, I'll see what he says. He wanted to know if I cleaned the grooves before I tried to install the rings. I cleaned them with some oil and blew them out but there was no way the top ring would have fit, much too thick. Well I'll see what he says then I'll try and get them locally. Mike

[D-17_Dave]

Yep. sounds like the wrong set. Hope you get it worked out. don't forget to knock off the glaze in the cylinder and wash it good so the new ring will reseat. If you've already cut the ring thickness down you could trim the ring gap to speck and use them. However most top rings have a groove in the top offset on the edge, I hope you didn't trim this off.

[Al]

HI, If the rings are too thick, you probably have the newer Mahe pistons that are used in the late sn K series and the M series engines and ordered rings for the old style pistons. As far as the end gap it needs to be checked below the ridge in the worn area at the top and down near the bottom below the ring travel. The minimum gap must be present at the bottom and should not exceed the max in the worn area. It is best to use the top of the piston to get the ring perpendicular the the wall or you will get false measurements due to the eliptical effect of not having the ring at right angles. If you don't make the min spec in the unworn area when the engine heats up you may get siezures, scoring or broken rings. You can determine which pistons you have by looking at the wrist pin area on the sides. If they are round they are the old style and if they have flats on the sides they are the Mahe style pistons. Each type HAS to have the correct rod to go with it. Al Eden

[wasmeneh]

Thanks Al, I'll go and look at it. Do you mean it will look like D in figure 11-4 in the Kohler Manual? (The Mahe type piston) I'm kind of stumped. I'll do some measurements tomarrow am. Thanks Mike

[Al]

Hi, I am 1800 miles from the shop, but the Mahe have flats on the sides. The rings are thinner. Al Eden

[Agricola]

To clean the grooves in a piston, take an old piston ring, break it and use the sharp, broken edge as a scraper. You push it around the groove a few times and that groove should be nice and clean, without any carbon.