Tillerman6 Posted March 21, 2021 Report Share Posted March 21, 2021 Guys, What is the standard break in proceedure for a new piston, rings, and a bore that has seen another piston? I honed after the first piston with a 280 grit ball hone, but after 3 hours- the rings are still not seated with about 50% contact right now. What oil and ratio should I use or should I re- hone the bore and try again? I have .012" ring gaps at the top of the bore right now. My oil was synthetic Amsoil at 30:1. There are several contact areas disbursed around the inside of the bore about 1" wide. What am I doing wrong or what would you change to get the rings to seat fully? Thanks in advance! Quote Link to comment Share on other sites More sharing options...
b40rt Posted March 21, 2021 Report Share Posted March 21, 2021 I'm curious how you know you have a 50% contact ? If you have stripped the cylinder off to check, what symptoms prompted this ? Personally, on an engine of that era, I would only ever use semi synthetic at 50:1. Generally once you have used about 5l of fuel, the piston should be fairly bedded in. Quote Link to comment Share on other sites More sharing options...
Tillerman6 Posted March 21, 2021 Author Report Share Posted March 21, 2021 b40rt- Well - my fault- I was installing a kill switch onto the handlebars and I had the spark plug out to check for spark and I dropped the tiny screw that holds the clamp together for the kill switch right on top of the head! Tinkle tinkle- the screw did not go down the spark plug hole, but almost did. Then I thought - what if something else did go down there? so out of extreme caution (now) I pulled off the head and had a look see- That's when I noticed the markings for the break in. The markings are vertical stripes about an inch wide. They don't look like deep scratches. Anyway- from now on I will throw a wide rag over the head any time the spark plug is removed. And on this bike you can have it all back together in an hour or two if you are just pulling off the head only. Quote Link to comment Share on other sites More sharing options...
feetupfun Posted March 21, 2021 Report Share Posted March 21, 2021 I would think that using a ball hone in a 2 stroke cylinder would pretty much guarantee an uneven honing pattern, so there would be an unusual visual effect from the rings on the hone marks. New 2 stroke rings usually take 10-20 minutes of gentle operation to bed in, spread over 4-6 heat cycles. Unless you are seeing darkening of the bore surface due to ring blow-by, I wouldn't do anything except ride it. Quote Link to comment Share on other sites More sharing options...
Tillerman6 Posted March 21, 2021 Author Report Share Posted March 21, 2021 Feetupfun- Hoing- The only info I had said that the 2 stroke cylinders should NOT be honed with a stone type - hone- as there is a tendency for the stones to get caught in the openings in the cylinder wall. They work fine on 4 strokes because there are no openings to worry about. And actually the 280 grit is pretty fine and does not remove much material at all, so if the cylinder was smooth before it was honed, it will not end up with any aberations from the honing process- and you are only honing for about 30 seconds or maybe 100 revolutions in a push-pull motion anyway. - And I did not see any darkening of the bore surfaces. So maybe I'm good enough to keep running it- I may go back to a 40 or 50: 1 fuel to oil ratio and see how that works. I might be running the oil too rich. Quote Link to comment Share on other sites More sharing options...
b40rt Posted March 21, 2021 Report Share Posted March 21, 2021 2 hours ago, Tillerman6 said: They don't look like deep scratches. Anyway- from now on I will throw a wide rag over the head any time the spark plug is removed. Cut down an old plug and use it to block the plug hole. Quote Link to comment Share on other sites More sharing options...
Tillerman6 Posted March 21, 2021 Author Report Share Posted March 21, 2021 I needed the cylinder to freewheel and breathe to check the spark and the control of the kill switch or I would have stuck another plug in there for sure- but thanks for the suggestion. Quote Link to comment Share on other sites More sharing options...
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