'Custom' porting

[motodreams]

I know the story but for fun I figured I would see if there are any guesses what is going on here? 

This is the first time I have seen this 'custom' modification to a cylinder!  Any one else see this before?

[m in sc]

yup.

ive seen a smaller bore yamaha that had something similar from the factory. looks like somebody got happy with a 1/2" endmill with a cyl and the cyl at a funky angle.

on my old h1, when boost ports were added above the intake did something similar, but a lot deeper and actually shaped.  boy they really want it up above the stock boost port line. 

[motodreams]

That's a negative on that one.  This was a little less intentional.

[m in sc]

wristpin?  holy shit thats a clean slice. how the fuck would anybody ride ti that long? that had to make a horrible racket

[motodreams]

You got it!

There was no circlip on that side and the groove is the same dimensions as the wristpin down to the bevelled edges.

It really looked like it had been machined at first.

The motor was turning over just fine and didn't appear to bind.

It is amazing nothing caught and self destructed. 

I think the power valve bolt came loose as well and one of the pins slipped in behind one of the PV ends damaging the valves.

[rd400canuck]

That's insane that cold even happen so perfectly

[motodreams]

My thoughts as well.  How it didn't explode is beyond me.

[thatguy]

My Harley did that. 

[1976RD400C]

I've seen a 70's V-8 engine do that.