R60 Engine Rebuild

[J-Sin]

I'm in the process of rebuilding the engine on my R60. What should I do for the break in period? What kind of oil? When should I change it? Should I keep under a certain rpm? How long is the break in period? Etc...Any help would be greatly appreciated!

[schrader7032]

IMO, the most important part of the break-in is the first 60 seconds! That initial start is where there is the least oil on the cylinder walls and will allow a good amount of ring seating to occur before they walls get hot and glazed.

Here's what I did for my R69S:

- start the bike and as soon as it will take throttle, get the RPMs up to around 3K and hold for 30-60 seconds. This is pretty hard to do...just sitting there watching the thing run!
- then immediately go for a ride, trying not to idle the bike too much, or stay in one RPM range. Don't go too high on RPM, probably less than 4K (you'll have to estimate that).
- vary the throttle between acceleration and deceleration...this helps load up the rings and press them against the cylinder walls for continued seating

After about 20-30 minutes, I came home, let the bike cool, and drained the oil. When the bike was stone cold, I rechecked the valve clearances.

At that point, I think I changed oil at 50, 100, 250, and 500 miles. I checked valve clearances, certainly early on (I didn't see much change) and then at the end. After that, I just started to ride it more or less normal.

I used BMW dino oil...I wouldn't use a pure synthetic, although using something like Golden Spectro 4 which is a semi synth might be OK. Personally, I would use the dino oil, since you're going to go through it quickly. You might keep the oil weight light during this period. I think I used 10w40 and have switched to 20w50...I live in South Central Texas. A straight weight oil 30 or 40w might also be good. You want an oil that has an API rating of SG. Later ratings (SM, SL) don't have the forumlation that's good for our engines. People also discuss the issues with the multi-vis oils as being not the best for the bearings in our engines...that's where a straight weight works best.

My 0.02...

[J-Sin]

Thank you! That's some very good advise!

[schrader7032]

Here's a reference to break-in procedures...somewhat along the lines that I mentioned.

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

[loftus7608]

okay guys, on my 1952 R67/2 I just put in new pistons/rings, had the cylinders resleaved/honed, and put in new rotating exhaust valves. This weekend I was about to begin my breakin period using the "slow" method and now the link from Kirk states just the opposite, use a fast breakin method.

Makes sense to me, does it pertain to our vintage bikes?

Cheers, Tom

[schrader7032]

Rings against cylinder walls...what's vintage about that?

I'd do some more research and consider what's going on. I'm sure if you googled "engine break-in" you'll find many websites.

There is the theory to "break it in like you're going to ride it." Might make sense if you were going to be at one constant RPM or gear all the time.

The whole purpose of break-in is to get the rings to change their shape and match the cylinders...plus to let the parts seat in like the gaskets, etc. This is done by wearing the rings in. My point was that once all the oil gets slung around and especially gets glazed onto the hot lower portion of the walls, it'll be so slick, not much wearing will be going on.

I think everyone would agree on the don't dwell at a given speed for a long time. If you just happen to hit the resonance of the engine, you'll create all kinds of havoc and parts won't match up at all.

The idea of accel/decel seems logical to me to keep those rings pushed up against the walls for more wearing in.

But in my estimation, the biggest part of the break-in is early, so consider how that's going to happen.

[miller6997]

I don't anticipate an overhaul in the near future, and I don't mean to be argumentative, but the article you link to refers to recent developments in manufacturing technology and metallurgy to justify the "quick break-in." Is it likely to be as valid for engines that are forty to fifty years old?

[Darryl.Richman]

I did a fast break in with my R51/3. Assembled it with just a wipe of oil on the piston skirts, then fired it and held it at about half redline for 30 seconds or so. Stopped, let it cool, the fired it up and started riding it how the BMW prescribes -- limited speed in each gear, but riding it in the hills, requiring much shifting up and down and a lot of change in the engine speed. Now, 12,000kms/7,000miles later, it doesn't use any oil and runs great.

My friend the former head mechanic at a dealer suggested it.

[schrader7032]

I don't anticipate an overhaul in the near future, and I don't mean to be argumentative, but the article you link to refers to recent developments in manufacturing technology and metallurgy to justify the "quick break-in." Is it likely to be as valid for engines that are forty to fifty years old?

Hmmm...I read the section from the link that says "Due to the vastly improved metal casting and machining technologies which are now used, tight parts in new engines are not normal. A manufacturing mistake causing a tight clearance is an extremely rare occurrence these days. But, if there is something wrong with the engine clearances from the factory, no amount of gentle running will fix the problem."

It seems they're referring more to the fact that a new engine parts will not match well. If that's the case, an easy run-in is not going to work all that well.

Wouldn't this be the same situation for an old rebuilt engine with new technology (rings and pistons made today)?

I think it just comes down to the sealing interface that is common to most piston engines made for the past umpteen decades. They really should be dealt with the same way. There are different rings out there...I've heard of something called "total seal" rings or something. Anyway, there may be a specific way that the company suggests to break those rings in and/or oriented in the installation for proper break-in.