Is this normal?

Fast6hand

Active Member
Oct 10, 2013
2,022
308
145
West Palm Beach
Was wondering if these marks are normal? They are not gouges. This is a KOR honing/piston job so I know the clearances are correct. I pulled the head because I have my rechambered head coming tomorrow.
image.jpg
 
You have a dirty assembly Boss or you're sucking dirt via the intake, carb, filter, pipe, or boot. Did you flush the inside of the pipe before you assembled the new top end?
The pipe no. But I'll make sure to do it this time. Is this gonna cause me problems? I'm running a uni filter that's oiled, and I clean it often. There are no leaks at intake either. The boot is sealed good on both sides of carb. Remember I have that leaky LRD pipe at flange. That could be the problem, or rtv from trying to seal it.
 
The marks are wear, produced by contamination by dirt or dust.

The contamination is still likely to still be present suspended in oil between the rings.

Oil will have a problem in hanging in the crosshatching and the rings may starve for oil!

If it were me I would remove the cylinder, wash piston and rings and give the cylinder a freshening hone.
 
If KOR did your cylinder and not too many hrs than I would give a medium to heavy hone and new rings. This should get you some almost free time till another top end. I'm a newbie but I pretty sure yer wiseco ate some funk a while ago.
 
Was wondering if these marks are normal? They are not gouges. This is a KOR honing/piston job so I know the clearances are correct. I pulled the head because I have my rechambered head coming tomorrow.
View attachment 13481

Don't rehone it or try to remove it. If it is what I think it is, harmless.

I have seen this before. No scratch or gouge, cannot feel it with your fingernail.
Your compression is probably normal. Not a problem, do not worry about it.

Seen it in 2 and 4 stroke engine rebuilds where dirt was not a factor, and like
you mention, these are not scratches, but polished streaks.

I don't think this is caused from dirt or scratching but is from ring burnishing.
I think, but cannot prove, it is is from too gentle a break in.
Put more load on during break in to prevent this, not idling.

Steve
 
Last edited:
  • Like
Reactions: Awk08
I don't think this is caused from dirt or scratching but is from ring burnishing.
I think, but cannot prove, it is is from too gentle a break in.
Put more load on during break in to prevent this, not idling.

Steve


I like that .....too gentle of break-in :)

I've always done...no long full throttle runs for a tank or 2 of fuel.
but yet lately I am seeing "no full throttle at all" posted like it's written in stone somewhere.
ALL rpm ranges should be used for break-in, including full throttle, just don't keep it at any 1 rpm for long.