J engine ring end gap

Worst nightmare! Finally got it running, setting end gaps bigger than out of the box, but .001' less than recommended by MTC, and I got lots of blowby. Smoking out the breather. I can smell it at a light.

Shouldn't be that bad with just the ring gaps on the high end.
Give them time to bed in, some hard accel and decel to push the rings in to the bore.
Should settle down..
I just done two more top ends, new Wiseco's, Rings wide straight out of the box but run just fine, no smoke.
Not happy though as they were over the Wiseco spec and it isn't the bore and hone that was wide..

zed1015 wrote: Shouldn't be that bad with just the ring gaps on the high end.
Give them time to bed in, some hard accel and decel to push the rings in to the bore.
Should settle down..
I just done two more top ends, new Wiseco's, Rings wide straight out of the box but run just fine, no smoke.
Not happy though as they were over the Wiseco spec and it isn't the bore and hone that was wide..

Hey zed. I think I may have fuel washed and scuffed the rings, pistons, and walls.

First start wasn't bad. Started fairly quickly. Got idle air/fuel in the mid-13s with the screws, but mid-twelves off idle. A short high pitch pop when I goosed it a couple times, figured from rich mixture. Been jetting to lean it out off idle a bit. One time after re-installing the carbs I may have flooded it adjusting new throttle cables (accelerator pump in the FCRs). Cranked like 15 - 20 seconds. It would fire a bit, but die if I touched the throttle. Flooded symptom from experience. I pulled the plugs, and they were wet. Dried them off and got it started.

Jetted again, and this time it cranked but wouldn't fire at all. I was getting ready to check for spark, hit the start button one more time. And it fired and idled on the first click. Very much like I had no spark, cycled the ignition, and it came back.

I know the worst time for fuel wash is at break-in, and this may have bitten me in the ass before. Before this top-end I had an intermittent spark condition on start up. Super random, weeks in between, it would crank away and no start. On one rare occasion it happened long enough for me to test, and there was no spark at both coils. Before I had a chance to check for voltage at the hot side of the coils, the problem was gone and fired up.

Since that happened I cleaned the contacts in the ignition switch, cleaned and tightened all terminals in the ignition circuit, kill switch is new, and it didn't happen again. But shortly after that I had to tear down the engine and fix everything. 

Now I think the problem is still there, and bit me again. Gonna do a leak-down test and view the thrust sides of the walls with a borescope. 

How many miles since the engine work?  What hone type and grit?  240 grit dingo ball hone is good.  I doubt the issue is/was a washed out cylinder. And a little vapor out of the breather is normal.

Maybe 20 miles since startup. Not sure on honing. APE did the bores.

Had a feeling. 5% to 8% leakdown by the rings. 



 

What's with the horizontal lines? 
Steve

Honing crosshatch. Looks too horizontal? I see what you mean. Looks like underlying it goes straight across. It could be the picture.

These scoring would made me some headache

Having a hard time orienting the photo.  Unless I'm misunderstanding it looks like there are deep vertical score marks in the cylinder.  Is this correct?  If so, could the rings have suffered damage during install into the cylinder?

Nessism wrote: Having a hard time orienting the photo.  Unless I'm misunderstanding it looks like there are deep vertical score marks in the cylinder.  Is this correct?  If so, could the rings have suffered damage during install into the cylinder?

Yes, vertical scoring. Left bottom corner of pic is top of bore. No issues on install. And the scoring is up past ring travel. Above the top ring.

And similar scoring on all cylinders.

Looks like wrong crosshatch. What do the rings look like? 
Steve