A lot of members have changed their chains. Locating a proper tool locally to deal with the chain link peening is probably the biggest problem. The other problem with keeping an older stretched chain is it slowly damages the sprockets the longer it gets.

The other concern is your reading 5-5.5 degrees stretch now. Yet reading only 3 degrees stretch only a month ago. If the additional stretch has really occured it could be signalling something is changing fast. Far too fast.

Most believe the chain fails because of a problem with another component. This may not be totally true in all situations. I find myself wondering if the pinging that became noticeable during the trip but not present during the initial part of the trip. Could that have been because of a sudden elongation of the chain? Moving the pump ahead seems to have gotten rid of it. That almost proves it in my mind.

When stretch is present the chain may side whip a little when running. This produces a lateral force component. If that over time does fatigue the side links the chain is going to let go at some point.

Still something funny here though. Or I should say at least beyond my grasp at the moment. Needless to say if the chain had suddenly elongated it would have retarded the injection pump and cam. That should not have induced the pinging. In effect it was just retarding the pump. I think the cam change was not signifigant enough as well but may be wrong here. Also strange the pinging should lessen when advancing the timing.

Since you are pretty sure your elongation tests where done by the same method. I would change that chain much sooner than later as you are questioning the sudden apparent change. At first I suspected it was just your method for the strange change in the readings. Not sure at all now when thinking this whole thing through.

I am a very slow thinker at times but re reading your posts seems to indicate you probably know what you are doing. Or at least enough to be in control of the situation. Some of the questions you have now seem to possibly add up. Not all mind you but certainly some.

You may also have noticed something almost by accident. Some chains might issue a warning. Most of us will never catch it though if true. A sudden increased of stretch rather than over time. We expect a new chain to stretch a little fairly fast when entering service. Not a well used chain to gain 2-2 1/2 degrees apparent increased stretch in a months use. Almost double of what it initially aquired over a lot of years.

Sorry about some of my earlier questions. There was no intent to question in any form of negative fashion. It was basically because things were not adding up correctly. Still are not totally but the chain has to go. In my opinion it is too risky not to change it. The 5.5 degees of stretch do not disturb me. Its the apparent rapid rate of change that does.

When you get the old chain off clean it in solvent. Examine all the links with a magnifiying glass on both sides. If no cracks are found side load the chain over various areas. See if the chain forms the same side radius over its length. Or are there almost kinks in areas. Post good or bad. It may help others down the road.

There have been recomendations by obscure parties to change chains out at every 150k. You might have discovered the reason it is mentioned here and there from time to time. Hindsight is great but those parties might have experienced or seen evidence of fatigue in some chains. Just a thought at this point.