Cylinder inspection/ ugly marks on cylinder

[JZ05220r]

I decided to check out and make sure the kips valves were all closed and hadn’t skipped/sheared any teeth on my e series kdx. That checked out fine. However I was caught off guard when I peered into the cylinder and noticed some markings in line with the bridges on the intake side. I always gave the engine a solid warm up before taking off. Doesn’t look good. What do you guys think could have caused this?

[SS109]

That doesn't look to be from a cold seizure. Did you check the ring gap? Were all ports chamfered?

[JZ05220r]

That doesn't look to be from a cold seizure. Did you check the ring gap? Were all ports chamfered?

I had Ken O’Connor rebuild this engine last year. Was stained and rusted to crap. So I assume he did make sure everything was correct. I noticed the marks are right in line with the bridges between the intake ports, about the same width as the distance between the ports. Pic for example.

[SS109]

Hmm, makes me think the port wasn't chamfered. Is it a sharp edge on the ports?

[JZ05220r]

Hmm, makes me think the port wasn't chamfered. Is it a sharp edge on the ports?

I’ll have to dig in further and find out. Thanks

[JZ05220r]

I don’t believe I ran the engine too lean. Used a 42 pilot, 1173l needle and 150-152 main. I understand it varies but I don’t think those sizes are too questionable. It did rev up quite high cold starting with the choke on using the 42 pilot but I was also religious with tipping the bike prior to get extra fuel and that helped remedy that.