J engine ring end gap

Earlier in the thread there is reference to how the "old rings" had shiny spots on them or something to this effect.  You also mention APE doing the bore/hone work.  Question: are you working with a new top end or has it been run previously?  If run previously, how did the bores look in terms of scoring, did everything get measured, and was a fresh hone job performed?  Reason for asking is that if this is a new top end and APE bore the cylinders, something bad happened to leave those score marks in the bores.

Nessism wrote: Earlier in the thread there is reference to how the "old rings" had shiny spots on them or something to this effect.  You also mention APE doing the bore/hone work.  Question: are you working with a new top end or has it been run previously?  If run previously, how did the bores look in terms of scoring, did everything get measured, and was a fresh hone job performed?  Reason for asking is that if this is a new top end and APE bore the cylinders, something bad happened to leave those score marks in the bores.

Bored by APE, new pistons n rings. First run, and this is what I got. Think It's got to be excessive heat, or fuel wash that caused the damage while tuning.

Doubt it.
Steve

zed1015 wrote: Must have been very cold/ damp to cause that but slight brown staining shouldn't have done anything.
As regards the cause ,who knows ? without pulling it apart but If it runs ok otherwise I would give it a chance and do a few hundred miles and see if it settles.
20 miles isn't enough for a determination unless something drastic happened.

I'm thinking the same thing, but know deep down it will never be 100% without hone, pistons n rings, again.

The advantage would be getting the carbs tuned, and figuring out my mystery intermittent no spark issue, before doing the top end again.

Disadvantage is dirty oil, and carbon build up in the head.

Right now I see blowby smoke out the breather, but not the exhaust. But there's already carbon on top of the pistons after 20 miles.

On a positive note. No more noise from the twisted crank and loose bearings in the crankcase. No leaks. And the transmission/clutch operation is perfect. Bottom end is 110%.

Well the rings might seat in if it runs properly. Mine's getting better all the time.
Steve

SWest wrote: Well the rings might seat in if it runs properly. Mine's getting better all the time.
Steve

We'll see, but I'm not getting my hopes up. From expeirience the borescope view can exaggerate damage, but the smoke out the breather doesn't lie.

Just took it out for a decent ride. Got the carbs in the low 13s cruising, and it pulls like a freight train. But the smoke out the breather hasn't changed. 

Out on the ZRX right now trying to forget about the KZ.

I can well understand this, it´s very frustrating to fail on the last steps of an bike/engine rebuild.
Drive carefully without anger!!!

Some fumes out the breather is normal.  I'd run the bike for a few hundred miles, medium hard, and then check the leak down again.  

Agreed, even with used rings the bike runs like a scalded cat with very little blowby.
Steve