Cylinder Liner Failure !

Anybody ever see one like this ? Looks like the Liner Cracked all the way around at the transfer ports and then the loose parts made there way up the Transfer Ports. This Motor had about 2 hrs running time on it since I went threw it. This is the 1984 AC 250 with all the extra Ports. I had Port Matched and cleaned them all up but I had never removed the Liner. When I bought the project it had the original rear Tire, and Piston. And yes the Rod lower end is shot to. This bike was running great and ( look at the spark plug color ) I was just ripping down the back straight. You would think that there was a big bang when this happened but it acted like it ran out of gas I used the kill button to shut it off. It wasn't till I realised the kick start was froze before I suspected any thing was wrong.

I have seen that once, when a piston ring broke and broke the liner.

Interesting enough I checked e-bay for repair parts and sure enough there is a complete 84 250 WR Engine with the correct Cylinder. Only problem is its had the same Cracked Liner issue ! Not near as bad, but the lower corner of the Liner is missing and the parts went up threw the transfer ports and did in the piston and head just like mine.

not enough MEAT in that cylinder liner with all those EXTRA transfer ports.

You will likely find a broken crankwell when you split the cases. I found that just splitting the cases to replace the crank seals in the 84 250WR I have.

My first 83 250 wr was on the last over sized bore. After a while the cylinder sleeve cracked at the bottom. It sounded like a kids bicycle with the clothes pin baseball cards flapping.

That's why not going to 144 my 125. Power Seal says I need at min 3 mm of liner or that will happen.

This Cylinder still had the original Bore and Piston. When I bought the Bike it still had its original rear Tire.

If the liner is fitted correctly this cannot happen as it is held tightly it's full length and diameter and it butts up against the head.
No movement no cracking.

Backing off and looking at things, The liner is Iron, Iron is used because of pores and carbon that give oil a place to be. The design considerations of liner material hence are compromised for resistance to the failure discussed here. As in many things mechanical after the fact it becomes apparent certain choices and manufacturing processes end up less than ideal.

Have about 20 odd 2 strokes in my shed at the moment all with cast iron liners and not a problem.
5 of them are huskys.
In my 50 year riding life I have had many 2 strokes [ love em ] and again I say " never had a problem".
Ever.
I have also worked a lot of years as a [ tradesman] engine reconditioner , most of my time spent on the boring bar and have fitted many sleeves to many different engines.
Never had a problem.
Ever.
Have seen 2 failures in my life and the above is one of them the other was a fitting fault from the factory [ sleeve was loose and moved ]

One of the biggest complaints about 2 strokes is that they "Seize Up " In my 40 + Years of Ridding this is my first Seize I have ever seen, and well it turned out to be a lot more than that. I have never gone ridding with anybody that's had one either. When I built this bike I spent a lot building it and the one spot I skimped on was the Piston and Cylinder. I figured it was a low hour bike and I would just run it and then do a top end once I got the rest of the bike sorted out. When waiting for the gate to drop I never really liked the way this motor sounded. In the morning I noticed that the bike had lost some compression when I went to start it. I was planing on doing a top end this winter, and I came up one lap short.

are the 165 bikes plated or sleeved? i believe darren is talking about sleeves only needing to be that thick, since he is referring to making an old swede 144 unless im mistaken

Kelly, older 82 125. When I punch it out to a 144 size. There is not enough liner to support bigger piston.
2 things power seal told me that would happen. Liner breaks or the skirt of piston will wear fast and break.
I found a piston that works size wise.