Running In R51/3

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Darryl.Richman
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Running In R51/3

Post by Darryl.Richman »

Peter, I've heard suggestions like this before, but have never done it myself.

After getting a bore job, new pistons and rings for my R51/3, I followed the owners manual's break in procedure -- essentially, limited speeds in each gear and doing a lot of riding in the hills, so that the motor saw a lot of changing conditions. It has been a strong performer in the 5,000 miles since then. Otherwise, it gets regular grade unleaded fuel (87 US octane, probably about 91 RON) and Castrol 20W50 motor oil.
--Darryl Richman

Barry Robin
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Running In R51/3

Post by Barry Robin »

peter-

darryl beat me to it-not a surprise-but i'd be writing the same thing he has on all counts.
i've used this basic run-in on all my post war bikes without problems (e.g.: R51, R67, R60...)

don't worry, it'll be fine with darryl's suggestions.
-b

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schrader7032
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Running In R51/3

Post by schrader7032 »

I recently did a break in on my R69S using information I'd heard from several sources. Once I got the engine running the first time, I immediately increased the RPMs to around 3000 and held it for 30-60 seconds. After that, I went for a ride of 20-30 miles, varying RPMs as suggested above and trying to avoid any idling. After the ride, I changed the oil. I used BMW 10w40. For at least the next couple of hundred miles continue to varying the RPM, getting both acceleration and deceleration loads on the rings. Changed oil again. I'm going to take this out to about 500 miles and change oil a final time before I call it good. At the change oil points, I'm rechecking head torque and valve clearances.

This initial break in process was somewhat "scary"...smoke was pouring off the engine, most likely the assembly fluids that were on various pieces. My understanding is that initial 30-60 second period is when you'll get the most wear on the rings, because the cylinder walls haven't gotten hot enough to glaze the oil. Once oil gets glazed on the walls, the relative friction goes down and there's no more seating of the rings, or very little. At that first oil change, there were quite a few silvery flakes in the oil from the wear process on the rings. The amount of silvery flakes was way down at the 200 mile oil change.

The bike seems to run OK but don't really know about the oil consumption as I haven't waited long enough. I did a cursory compression check with a cold engine (I know, it should have been warm) and I got 125psi IIRC which seemed reasonable for a cold engine...it should go up from there when warm. I also did a leak down test and was getting 10% leaking past the rings...again on a cold engine. Before the teardown, I was getting those same numbers but on a warm engine so it looks like the teardown improved things.

I guess time will tell...

Kurt in S.A.
Kurt in S.A.
'78 R100/7 '69 R69S '52 R25/2

Allan.Atherton
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Running In R51/3

Post by Allan.Atherton »

... I immediately increased the RPMs to around 3000 and held it for 30-60 seconds.... smoke was pouring off the engine... At that first oil change, there were quite a few silvery flakes in the oil from the wear process on the rings. The amount of silvery flakes was way down at the 200 mile oil change....
That smoke-in method is slightly less controversial than the Bon-Ami method ;-)
Wearing-in of ferrous rings does not make silver flakes. I think the only possible source of silver flakes is tight aluminum timing gears. A lot of that material must have gone into the slingers.

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schrader7032
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Running In R51/3

Post by schrader7032 »

Wearing-in of ferrous rings does not make silver flakes. I think the only possible source of silver flakes is tight aluminum timing gears. A lot of that material must have gone into the slingers.

Interesting, because the timing gears were not changed as part of the overhaul. Just the bearings and the slingers were cleaned. A complete top end was done, including valves, guides, and rings.

Kurt in S.A.
Kurt in S.A.
'78 R100/7 '69 R69S '52 R25/2

Allan.Atherton
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Running In R51/3

Post by Allan.Atherton »

Wearing-in of ferrous rings does not make silver flakes. I think the only possible source of silver flakes is tight aluminum timing gears. A lot of that material must have gone into the slingers.
Interesting, because the timing gears were not changed as part of the overhaul. Just the bearings and the slingers were cleaned. A complete top end was done, including valves, guides, and rings.
Kurt in S.A.
The rings are iron and the amount of material that is worn off in seating is very small, like a polishing. Likewise the cylinders are iron, and the honing marks that are worn off of them is a polishing. The iron particles polished off the rings and cylinders are invisibly fine, not flakes, and I wonder if they would be enough or the right color to make the oil silvery.
The timing gears are aluminum and can lose material if tight. Usually the material appears as a silvery sheen in the oil, like metal flake paint, but if the fit is very tight, feelable flakes or slivers can be produced. I wonder what else besides the timing gears can produce silver color or silver material in the oil.
Timing gears are removed to replace bearings and slingers; I wonder if it is possible for something to change so the gears go back tighter than before.
My rebuilt R27 and R69US broke in very quickly, and the initial oil changes at 100 and 500 miles were clean. The oil had darkened somewhat, but contained nothing. After break-in, the oil did not become dark amber for 1000 miles.
My rebuilt R60/2 immediately had black oil with a silver sheen. The PO had just previously rebuilt it with mismatched timing gears, which my mechanic honed to fit as best he could. And the new rings did not seat. After getting a second set of rings with different oil rings, the rings seated, the oil became clearer, and the bike went on fine for 10K miles until I sold it. But the engine always darkened its oil by 500 miles, and had a little timing gear noise which was only apparent if compared to another better engine.

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schrader7032
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Running In R51/3

Post by schrader7032 »

Allan -

I understand what you're saying about iron versus aluminum parts especially during the break-in process. I may be overstating or mispresenting what I saw...I don't really have much experience with this sort of thing. This is the first time that I've broken and engine in in the past 20 years. I tried to take pictures of the oil, but the camera just couldn't resolve what my eye was seeing. I changed oil after 20 miles and saw what I saw. The next oil change at 200 miles, I saw very little of the "flakes" and the oil was brownish as expected. I'll change oil in another couple of hundred miles and I hope to not have any problems down the road.

As for the mesh of the timing gears, I've heard a discussion about how the distance between the gears closes up over time. Duane's thought is that the constant pull of the pistons outwards would tend to bring the other (vertical) direction together to compensate. I don't think the mechanic changed the gears...not sure if he measured the distance. I was around when that work was being done, however, before lunch, the crankshaft was out of the bike, and when I returned later, everything was basically assembled. :-( I kind of wanted to see that process.

The bike had about 30K on it for this service...the bottom end had not been out prior to that based upon the fullness of the slingers. The top end had a valve job at some point in the past, botched from what the mechanic could tell.

Kurt in S.A.
Kurt in S.A.
'78 R100/7 '69 R69S '52 R25/2

Allan.Atherton
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Running In R51/3

Post by Allan.Atherton »

... As for the mesh of the timing gears, I've heard a discussion about how the distance between the gears closes up over time. Duane's thought is that the constant pull of the pistons outwards would tend to bring the other (vertical) direction together to compensate. I don't think the mechanic changed the gears......
I think the closing distance between shafts is matched by the normal wear of the gears, and the gears never need to be changed for that reason alone.

But gears do get changed for some reason. My R60/2 had mismatched gears. And my rebuilder told of a bike with mismatched gears where he bought a supposed match, installed it, found flakes in the oil, tore it down again, and found the matched gear had been falsely remarked.

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VBMWMO
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Running In R51/3

Post by VBMWMO »

Howdy all, I am running in my R51/3, the mechanic suggested as follows,

Add on cap of two stroke oil per refill of fuel for the first few thousand miles then use an upper cylinder head lubricant thereafter.

Does anyone have a comment, confirmation or the like on this. Is there any other matters I should be aware of while running in?

Bad joke time.......I had a dream last night that i was a muufler and this morning i woke up exhausted. At least it's clean..........
Dedicated to the Preservation of Classic and Antique BMW Motorcycles.

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