First engine inspection/rebuild on an R69S

[jtaylor]

Greetings to you all-

I understand there are plenty of rebuild threads out there, but as this is a new and somewhat daunting experience for me I thought I would document the process of learning as I go - and hopefully acquire some additional guidance from the collective knowledge base of the VBMWMO along the way. The end goal (aside from a well-sorted and successful rebuild) would be to also allow others out there to learn from this process and corresponding information.

To begin with, I purchased an R69S in 2018 with just a shade over 50k miles. The bike had been previously restored and assembled over 10 years ago, but I don't have a whole lot of information about it's former life before the acquisition. Over the past year I have continually had some challenges starting it (both from cold and hot) and have always noticed a distinct tap or knock from the left side of the motor at all speeds when running, and to this date I have only put a couple hundred miles on the bike. On the hypothesis that it was possibly a top-end issue, I confirmed that the valves were all adjusted properly, checked rocker arm end play and confirmed the pushrods were straight on both cylinders; no change in condition. However, upon draining the oil from the crankcase, it appeared to have a somewhat metallic sheen (yikes!) so I knew I would be tearing into the motor and I promptly stopped riding it completely. The previous owner said that the slingers had been cleaned not too long before, but be that as it may I plan to investigate and attempt to determine what the causes of the noise and the metal breakdown are and address the problem(s).

I am not in any way a professional mechanic, but I do have some limited knowledge of the fundamentals and have slowly been re-acquiring tools (I lost everything in the CA wildfires in 2017). I have obtained a copy of the original BMW shop manual, parts breakdown and the Barrington restoration guide, as well as some of the recommended specialty tools from Cycle Works.

As far as I'm concerned, I'm simply acting as the current custodian/caretaker of this machine while it's in my possession and want to do the very best I can to properly maintain it while it remains as such; I consider myself very fortunate to have the bike and want to do right by all the previous owners that had it before me. Beyond the basic work and analysis I plan to outsource any machining or specialized rebuilding beyond my capabilities, and will of course be open to your thoughts and good advice when that time comes.

Let the tear-down begin!

Jeff

[schrader7032]

Jeff -

Look forward to the progress. As for the origins of the bike, send an email to the BMW archives and provide them with the VIN and any other info you have. They will let you know what they have on the bike.

info.grouparchiv@bmwgroup.com

Also, type the VIN in the engine square on the left side of the screen. That will take you to a page and at the bottom of the page is a list that I update from time to time. That will let you place the VIN among other entries to get a rough idea about the bike. More information can be added to the list to make it more complete.

[jtaylor]

Kurt, thank you kindly...I have done as you suggested and will await a reply.

Began preliminary work today; removal of exhaust system, intake, etc. The exhaust nuts came off easier than I expected considering the multitude of problems that many have previously related (ie: having to cut them off due to seizure). After applying pb penetrant over a couple days they spun right off. (There was also evidence of some type of anti-seize which probably helped, all things considered).

Upon removal of the head, it appears there is a fair amount of carbon build-up on the piston crown, as well as some scratching along the cylinder walls; cross-hatching from previous honing is still very visible, however. Haven't removed the barrel yet, but I surmise there is some skirt wear...the inside of the head and the oil in the bottom of the valve cover showed evidence of small abraded particles that are non-ferrous (alloy) which may prove to be of the same origin.

The picture below of the head shows the intake valve on the left; exhaust on the right.

[schrader7032]

So the heads are dual plugged? That's not a typical mod done to the /2 bikes...usually you see that on the post /2 Airheads.

[jtaylor]

Indeed, you are correct on both counts. The bike is not what I would call stock/factory spec. There's too much to list here, but suffice to say that there are a number of modifications overall; the electrics in particular were changed before my ownership to a VAPE mag with an Emerald Isle coil running to dual plugs. It still retains the standard points/condenser, however, and I have thought of possibly changing over to electronic ignition as well. Aside from the engine noise mentioned at the outset, I've had quite a bit of frustration in simply starting the bike (which may have a whole combination of root causes, of course) but I'll need to do further research to determine if this alteration would be a wise investment once I get the other issues sorted. That's all getting ahead of myself, though...I'm still quite a ways away from the point during reassembly where I"ll need to make that decision

[Twocams]

Your second picture of the head. Almost looks like the head gasket was leaking. I see exhaust marks going toward the big hole.
Or is that just the photo?

[jtaylor]

Twocams, your question is well taken; what you see is mostly due to my bad photography and the fact the head gasket separated a bit and adhered to the head in that location. After examination, I didn't see any evidence of blow-by or escape of oil, gases, etc.

Thanks for your scrutiny, though!

[jtaylor]

Well, after spending some further time in disassembly this morning, the left cylinder lifters exhibit some significant pitting; haven't pulled the cam yet, but of course that looks correspondingly bad, too (and my morale began sinking...) I've attached images of these and the left piston showing skirt damage.

Pushing through the frustration, I worked on the front engine electrics. (Note: I realized that I made a mis-statement before...The VAPE unit I spoke of is in replacement of the stock generator). Anyway, no trouble removing the advance, coil or magneto, but I came to an abrupt stop once I saw how the VAPE rotor/flywheel was mounted - the standard mag/rotor puller will not work here. After doing some digging, it appears that VAPE sells a special tool (#99 99 799 00) to remove it:

https://www.vape.eu/en/Puller-m27x1-25-m12-screw-m12x90

The website says it's available in 4 weeks (!@%$)

Any thoughts out there on another source, or does someone have one of these to sell? Otherwise it looks like I might be waiting a while to go any further...

[wa1nca]

Call Joe he may have one
He was the importer for mz for the US market


Contact Information
Contact Joel Rapose
Phone: 8059871750
Location: Camarillo, California, United States

[jwonder]

The website says 4 weeks for everything but it shows up in 2 days. Order it and it will be there before you know it. I have no clue why they do that.