reseat rings

[hadaveha]

Ok this is pretty embarrassing, on my 1981 gs650g I cross threaded a spark plug, I know what a stupid mistake, but I have pulled the head and retaped the whole, here in lies the problem when I put the head back on with a new head gasket, and put everything together, I cant seem to get my rings to seat, I'm getting blow by. Any tricks that anyone has to reseat a set of rings that has been setting, without breaking down the engine would be very much appreciated.

 

[GregT]

Couple of questions...I'm assuming when you say blowby that it's smoking. How long did it sit unused ? Did it smoke prior to this happening ?

If you've turned the job around reasonably quickly and it had run well previously, I'd look at the head gasket rather than the rings. It could well be oil leaking into the bore rather than past the rings.

And to cover another base - Did you change the oil perchance ?

 

[hadaveha]

sorry I did leave some info out, ok it sat for maybe 3 yrs, I have adjusted valve shims, rebuilt carbs, replaced all gaskets, yes it is smoking, I did check compression it is about 15 lbs lower on cylinders 1 and 4 than 2-3, runs amazingly well she just smokes, not lot burning car tires just a small amount of oil smoke, worse when cold and at idle

 

[fastbysuzuki]

If you have had the head off I assume you changed the cylinder base gasket whilst the head was off? If so any sticking rings would have been easily seen and freed off.
change the oil and filter and ride it fairly hard for a hundred miles or so and check the compression not forgetting to do it hot with the throttle held wide open.
what was the compression readings on each cylinder?

 

[Steve]

I am going to second fastbysuzuki's question: Did you change the base gasket? :-k

If not, I'm going to have to go into Clint Eastwood mode: "How lucky do you feel, punk?"

No matter how careful you are, the process of removing the head WILL disturb the base gasket. If it happened to stick to both surfaces, it will tear into two layers, and there is no guarantee that they will go back together well enough to seal.

.

 

[hadaveha]

well I must say after some hardish riding, not a speed demon here she is really clearing up, id say 80% better and the compression numbers seem to coming back

 

[Guest]

Always inspect and hone the cylinders when apart and practice a good hard first start.
And measure ring gap. Used rings are fine if in spec.