How long for new rings to seat?

[singletracker]

I finished rebuilding my topend today. I only did it because it had about 100 hours on it, and the race season is starting. The cylinder and piston looked great.

Before I rebuilt it the compression tested at 191psi, which is about what it was new. After running it through three heat cycles after the rebuild it tested at about 186psi. The heat cycles consisted of two short rides of about 5-10 minutes each, and one 15 minute ride. I let the bike cool down completely between each ride. I'm hoping the rings aren't completely seated yet, and that the compression will come up more.

How long should it take for them to be completely seated?

 

[rgranger]

they don't really "seat" anymore, not with the coatings on the cylinder wall, its too slick. just put a few quick heat cycles on it to seat the head, jug, gaskets.

 

[gasgasman]

True.

Did you go back with the same thickness base gaskets?

 

[singletracker]

Yep, same gasket thickness, and OEM piston and rings that came with the "Race" package when I bought the bike.

 

[singletracker]

False alarm. I checked it again real quick, and it checks out at 191psi now. I must of either misread it or had some lame kicks the first time around. Old age I tell ya, either its my beat up knee or I had a senior moment.

On the bright side, I'm impressed with how well the original top end held up. I believe it could've went awhile longer without issues.

 

[Rob_NZ]

Barring any incidents im planning to do 150hrs on my 2010 300.
I know of several that have done that before the top end was removed, and still looked pretty good.

I trail ride, no racing and my pace is best described as "moderate"

 

[singletracker]

I believe it.

 

[(F5)]

I finished rebuilding my topend today. I only did it because it had about 100 hours on it, and the race season is starting. The cylinder and piston looked great.

Before I rebuilt it the compression tested at 191psi, which is about what it was new. After running it through three heat cycles after the rebuild it tested at about 186psi. The heat cycles consisted of two short rides of about 5-10 minutes each, and one 15 minute ride. I let the bike cool down completely between each ride. I'm hoping the rings aren't completely seated yet, and that the compression will come up more.

How long should it take for them to be completely seated?

My initial reply to this thread was going to read
BRRRRRRP, [click]BRRRRRRRP
done


but I decided against it.

I've only ever found com testers to be wildly variable on 2 strokes. only really useful as a failure test. Differing amount of oil thrown up changes readings as well.

 

[nambo-trev]

Yep, same gasket thickness, and OEM piston and rings that came with the "Race" package when I bought the bike.

That was awesome when the bikes came with the spares kit!

 

[Fred1956]

I'm a fan of leak down testing for this reason, if proper squish is set then as long as sealing components are sealing-rings & head gaskets, then all is normally well. My leak down tester gauge shows 10-40% leakage to be OK but I prefer the low side of that range, if it gets over 15-20% leakage then I'm 'going in'. On my 250 at estimated 100 hours it is at 12%

 

[(F5)]

I'd like to say I'm a fan of ring leak testers (as opposed to crank case leak testers), but when my one arrived I can't get it to pressure properly like a friend's one, so think the regulator is dickie. His one sure showed up a problem on another engine, so I'm sort of a fan, . . .just not a fan of mine.