Ceased Piston Rings

[93KX5Rider]

So I was riding WFO down the road today and I pulled in the clutch because I was slowing down to turn around and the bike stalled. I jump started the bike twice with the momentum I still had but it died both times right away... I got off and push on the kick start and it went down as easy as a knife goes through butter. No compression. I walked it in the hot sun 20 minutes to get back to my brothers house and we pulled off the cylinder head and the jug and the piston rings are ceased but only on the side of the exhaust port.... Anyone know why this might have happened? The engine has had some work done by Kustom Kraft by one of the previous owners. I don't know for sure what was done to it but I think it may have been ported for top end... Anyways the piston rings were only ceased across the piston where the exhuast port is... the other side was fine. Let me know if you got any ideas about whats up with it. Thanks guys.

[kaw rider]

post some pictures

[KX5Zuki]

I did that because of low coolant, did you bleed your coolant system? The exhaust side gets alot hotter than the intake side, and that will always be the side of seizure. Sounds like you just got it too hot.

[Johnniespeed]

There are guys on this site who know much more than I do, but does it look like too much heat caused the siezure or is it siezed due to lack of lubrication ? What is your oil to fuel ratio ? Did the intake boot crack and lean out the mix ?  Is the igntion timing correct ?  If you can post some pictures someone should be able to identify the cause.
 John

[93KX5Rider]

I topped off the coolant with extra coolant and the gear box with a touch more oil. We did bleed the coolant and it looked fine. The fuel ratio I run is a bit lower then 50:1, I put 300ml premix in 10 litres of premium gas, so whatever that is I dont care to do math right now. and when we pulled off the top end everything was nicely lubricated in the bottom end and the cylinder. The cylinder was fine thank god.
here are some photos.

Exhaust port side.


Side view.


Front top view.


I also checked out the old piston I took out and replaced with the wiseco piston and the old piston(which is still good thank god) has porting above where the wrist pin goes in. Sooooooo that's interesting. My brother in-law and I are going to hone the cylinder and put in the other piston with the porting which came with the bike. And these bikes are supposed to be ridden hard and get hot, people ride these things all day flat out in the desert, so this shouldn't happen but it does when something is wrong. Thanks guys

[KX5Zuki]

Looks alot like the last piston I melted, was due to a coolant leak that I didnt notice. Noticed the low coolant after the meltage, and I did top it off before the trip.

[93KX5Rider]

The coolant was okay after the trip as well though. Anyways, I honed the cylinder and put a different piston in. It started up fine. I'm selling the bike. Too many problems with it.