Ring Breakin Time

[dougjordan]

Burning 1 qt. of oil in 400 miles. 1300 miles on bike (78 R100) since I had the heads rebuilt, new rings in a in spec 1st over size bore that was honed. My question is. Ride more miles or replace rings with new set of luftmeister three piece I have. Or just get new cylinders and pistions. Also on the last compression check one cylinder was 125 other135. Any advice appreciated .

[20774]

One way or the other, the cylinders are going to have to be pulled. You may only need to deglazed and hone the current cylinders. If you're still at the correct dimensions for 1st oversize, then put a new set of rings in it and perform the break in process differently next time. If the cylinder walls are allowed to build up glaze during a "mild" break in process, the rings will never seat. This has been posted before, but this website offers ideas on how to break the engine in.

http://www.mototuneusa.com/break_in_secrets.htm

[vanzen]

This guy at mototuneusa talks as if he's got a NEW idea about break-in proceedure.

Oddly enough, it is virtually the same as rec'd for the old air-heads by Udo Gietl – 30 years ago !

from "King of the Boomers", Kevin Cameron, March, 1979:

...He (Gietl) reasoned that too good an oil film could stop the break-in prematurely.
He therefore adopted a dry break-in procedure. The pistons, rings and cylinder bores are solvent-cleaned and assembled dry save for a drop of oil on each piston skirt. The engine is started and run at half red-line for nearly a minute. Upon teardown, the rings will be seen to have seated very nicely ...

and ... dougjordan, hope you're not trying to "break-in" with synth oil – it won't work ...

[beemerPhil]

Where is the oil going? ie, when do you see smoke? Are there any other leaks?

Was the "spec 1rst oversize" a new rebore? If not, did you measure for ovality and taper?

How did you break in the new rings? The most common mistake in this process is babying the engine- rings that don't seat within a few minutes after first start-up may never seat at all.

What brand and weight oil are you using? Different oils behave differently in boxer engines-

If you can get access to a cylinder leak tester, the results may be much more revealing than a compression test-

Best advice is to find someone with successful experience in rebuilding airheads, and make friends! There are specific steps required for best results that are definitely not intuitive and probably conflict with what you expect.
The short story is that if you broke in your boxer engine according to the suggestions in the rider's/owner's manual, you'll need to start over from scratch.

For more details, check this thread- http://www.bmwmoa.org/forum/showthread.php?t=32391

-and the post above this one.

[Na Cl K9]

...He (Gietl) reasoned that too good an oil film could stop the break-in prematurely.
He therefore adopted a dry break-in procedure. The pistons, rings and cylinder bores are solvent-cleaned and assembled dry save for a drop of oil on each piston skirt. The engine is started and run at half red-line for nearly a minute. Upon teardown, the rings will be seen to have seated very nicely ... Be sure to have a couple of good fans on the cylinders as the heat builds up rapidly. Also, a good battery is a must since the starter motor has to push parts through a dry bore. As soon as smoke stops coming from the exhaust which may take more than a minute in practice, turn the key off. Wait till it's cooled and change the filter and oil. There-after ride it like you stole it. This process is for Iron lined cylinders.

[20774]

Be sure to have a couple of good fans on the cylinders as the heat builds up rapidly.

I broke my /2 in using the "dry" method...heat doesn't build that rapidly...we're not talking minutes and minutes. After 30-60 seconds, lower the RPM, and ride off. Personally, I don't think the fans are necessary for this situation.

[crazydrummerdude]

I broke in the rings in m R75 and R90 using that same dry method.

I didn't use fans, but it couldn't hurt it.

[dougjordan]

Where is the oil going? ie, when do you see smoke? Are there any other leaks?

Was the "spec 1rst oversize" a new rebore? If not, did you measure for ovality and taper?

How did you break in the new rings? The most common mistake in this process is babying the engine- rings that don't seat within a few minutes after first start-up may never seat at all.

What brand and weight oil are you using? Different oils behave differently in boxer engines-

If you can get access to a cylinder leak tester, the results may be much more revealing than a compression test-

Best advice is to find someone with successful experience in rebuilding airheads, and make friends! There are specific steps required for best results that are definitely not intuitive and probably conflict with what you expect.
The short story is that if you broke in your boxer engine according to the suggestions in the rider's/owner's manual, you'll need to start over from scratch.

For more details, check this thread- http://www.bmwmoa.org/forum/showthread.php?t=32391

-and the post above this one.

The bore was not freshly bored. Just ball honed
I used a dial bore gauge to get the measurments.
Went together with a drop of oil on the skirts and ran at 4000 rpm for
a minute. Oil used was castrol 10-40 for 100 miles then spectrol 20 -50 dino.
Kept tac between 4000-5000 when rideing.
May be I will try again with three piece rings.

[20774]

Kept tac between 4000-5000 when rideing.

Your break in approach sounds decent, but you need to vary the RPM quite a bit during the first 50-100 miles. You want the pressure, both from acceleration and deceleration, to force the rings up against the bores to continue the seating process. Holding it at a set RPM is definitely not good.

[beemerguru]

And you did assemble the rings with the correct orientation :whistle