GuessI been replyin in the wrong place to answer a reply.
Not really 80mph I heard the rear cylinder drop I looked down and saw smoke from the breather and I hit the switch and pulled over. right in front of CO, State Patrol.

 

looks like it torched the piston first..

 

Wow...

 

What year and model is the bike? Also how many miles on bike?

 

Looks like a great winter project.

 

Unless you disassemble the whole motor and replace the crank shaft, the engine is bound to fail sooner than later.

 

Not so sure about that.. Without seeing the bearing or crank, it is an unknown.. More likely is the jug is beat silly from the wrist pin dancing around without a piston..

Looks like pre-ignition or detonation took hold in the motor and caused the piston to self destruct.. Motor should be completely torn down and cleaned and inspected..(piston frags)
A nice chunk in an oil relief or galley would certainly cause catastrophic failure.


Could use a lot better pics of the first ring groove and land..

 

And timing had been the same for 4yrs. with lots of miles(no speedo)another reason I thought it was just exhaust.

 

1992 EVO, FatBoy Trike. milage unknown, just replaced crank bearings never removed pistons from cyl. Cylinders are just past honing to be right so there in the shop being boared .0010 over

 

I removed my outer primary cover only to discover that the jam nut for the clutch adjustment came off. I thought the only damage was to the webbing on the inside of the cover. Cleaned all the metal chips out (paint brush, air hose, paper towel) until couldn't find anymore.

The engine needed to be disassembled (different issue but same parts slapper who did the clutch work) and there was metal chips behind the rotor - chewed up the new stator and all the bearing inside of the primary was also shot - small particles acted like 80 grit sand paper.