R62 Project: The Beginning

[Bruce Frey]

That is what I will look for!

I am always a little nervous when shopping for others if I am not familiar with that particular bike. There are only a few vendors that I have enough confince in to take their word for something like that.

Best regards,

Bruce

[Barry Robin]

thanks, bruce.

i always thinks of the R11/R16 plate as being just like an R12-just flatter.

if you do find one i can always send you the money via paypal; no reason for you to not have the ready cash for yourself (damn-i can't buy that left-handed nose inhaler with the bmw logo, now that i've spent my money on this stupid plate!)
take me away, calgon!

-barry

[Peter D. Nettesheim]

DSR,
A little info. First, the split piston does not have the split as an inexpensive way to compensate for expansion. New pistons are what is known as "cam ground" In other words the piston is not round. It is wider perpendicular to the wrist pin. The narrower portion is manufactured this way to permit expansion in this axis.
The earlier split pistons were not cam ground. They were round. The only way to permit a round piston to expand is to put this cut into it. That is why it is there and that is an old piston.
As far as the engine never being apart, I'm not so sure on this one as from one of the pictures I see you are missing internal engine parts. In particular the cover for the front main bearing behind the removable breather gear insert. The oil flow in this engine is a bit tricky to understand and you are missing one of the main parts.
That engine will require line boring to assure proper crank bearing alignment.
You have got some work ahead of you. Good luck.
Peter D. Nettesheim

[Darryl.Richman]

Peter, thanks very much for the reply! I guess I am going to need some information regarding the way that the bearing is supposed to be set up. The parts book only shows the entire bearing and and body as one piece, as a side view, and doesn't elaborate about what's inside.

Regarding the pistons, I must admit that I am just repeating what I was told by what I thought was a reliable source. I understand about pistons not being completely round to take up the uneven expansion due to the strengthening for the wrist pin.

But neither do these pistons seem to be original. The parts book clearly shows the originals have 4 rings, with one oil scraper below the wrist pin. These are 3 ring pistons.

In your experience, do you think that the cases absolutely will require line boring? I guess I would have preassebmled the case halves and then checked for runout, the way one does on a /2 or /3 motor.

If you can assist me with more information here, I'd really appreciate it!

[Peter D. Nettesheim]

DSR,
There is a lot of things to look at with this engine. I hate to admit it but I learned quite a bit from various mistakes I have made when rebuilding these(R32,52,62,63,57,12,11), and they are all very similar engines.
First, I dont think you will really have to line bore it. Think of the dificulty of doing this job. First you would end up cutting off the oil feed ports on the bottom half of the engine case that also act as locating pins for the bearing retainers. Then you would have to replace them and make larger bearing retainers to fit. Its not practical.
I started thinking of all the items to watch out for such as:
1)Watching out how tight to make the bolt that holds the front cam bearing in,
2)Confirming the main bearings are tight in the bronze bearing retainers and then in the case,
3)Measuring clearance for the front breather cap that surronds the breather ring on the front of the crank
4)Confirming that there is proper oil flow to the front gear set
and so on and on and on.
I have seen mistakes on each and every one of the above items that ended up causing complete engine failure. Fortunatly I learned before I rebuilt mine.
As I said..good luck, I'll try and help where I can but you are starting with something that looks rough.
Peter D. Nettesheim

[Peter D. Nettesheim]

OK DSR,
I am now going to give you a few questions. The purpose of the questions will not be to test your knowledge but to get you to think about why certain things in that engine were done the way they were.
1) Why does the engine case casting surrond the flywheel? This make no sense to the untrained eye as it requires the engine case to be split to do a clutch job. Why did they do this and why were they able to avoid this in the next series of engines (eg R12)?
2) Why is the little bolt on the right side of the engine the only one that is wire tied?
3)Explain how to time the magnito.


Get these right and you win...................three more questions.
good luck
Peter D. Nettesheim

[Darryl.Richman]

Peter, thanks again for sharing your insights. I'm very interested in your questions...

1) I have no idea, but exactly what you're saying has occured to me. As I learned in the R11 thread, early on in that model they changed away from the two slide BMW carb, which mounts to the back of the bell housing and uses an openning there for it's filtered air intake. (BTW, if you understand why pulling the air from around the clutch is considered some kind of filter, or even what the rationale here is, I would love to know.) Anyway, this detail is the only thing I can think of that might be relevant, and yet I cannot see how. So, definitely count me amont the untrained!

2) That bolt locks the front cam shaft bearing housing in place, and so it, along with a few other bolts that, were they to come loose, might be particularly dangerous, were safety wired. (The bolts holding the driving dogs flange to the crown wheel in the final drive, and the screws that hold the windage plate over the sump, are others I can think of.)

But that does bring up a question for me: once the bolt is removed, what is the secret to removing the cam? There's a blind bushing at the back, but I don't want to beat on it with a drift. There's no obvious puller location provided in front. Is heat my friend here?

3) I have read the owner's manual a number of times, but I can't quote it verbatim. Basically, the crank is placed into the crankcase with the pistons set to OT. The cam is set so that it's driven gear has the two adjacent teeth with marks surrounding the intermediate gear's marked tooth. Only then can the cases be joined, and the cylinders installed. From here, the motor is set to -- I forget the exact number, but it's about 9mm -- before OT on the #1 (right) cylinder. One actually backs up the motor and then brings it to this point in the forward direction so as to take up all the lash. Now, the magneto is set to just breaking for the #1 cylinder, and installed.

If nothing moves while doing all this, then the motor has just been timed for full advance.

[Peter D. Nettesheim]

Ahhhhh!
Now we are getting somewhere! I'll start from the beginning and give you the explainations. Your answers show you are thinking but you missed a couple of key things. First to question number 1
1) The rear of the engine is enclosed as doing so substantially increases its strength in that area. In particular around the rear bearing retainer which is under pressure to flex. It is the same reason that an angle iron has more strength than a flat piece of steel. The metalurgy of the time was not the best and they needed to form the back of the case in this way to add strength. As the casting processes advanced together with the quality of the metals this very non service friendly casting was dispensed with. What I liked in your answer is that you picked up on the whole flywheel intake thing. Here's the answer to that question:
Air filtration was primitive at the time. The engineers needed to design an intake system that could supply dry clean air. How to do this? Increase the length of the intake tract giving more time for dirty particles to drop out of the incoming air. Look right from the start of where the air enters the engine. Where is it? It is behind the cylinder where it is protected from a water splash, pre heated upon intake and far from the intake valve. It then has to circumvent the spinning flywheel which acts as a centrifical cleaner before it enters and then doubles back through the carb and down the long intake tubes. Its much cleaner by time it gets there.
Now to answer question 2:
2)I have to say that you almost got this one but you missed the critical issue. The bolt is not wire tied as to protect a dangerous or catastrophic failure if the bearing it holds would come loose. You are using the typical reason bolts are wire tied and it does not apply to this small bolt. Why would you need to wire tie a bolt in place? In this case its because you cannot tighten it to the torque a bolt of this size would normally have. Why? Because, if you did you would radially load the cam bearing, distort it and cause its failure. Understand? So now you have to leave it a bit loose, only tight enough to hold the bearing in place but not tight enough where it will stay in place. How to prevent it from walking out? Wire tie it!
As far as removing the cam, you need the correct tools.
Now to number three.......
3)You are really close on this one too but I don't like the whole crank placement issue as this is not pertinent to the task. What if you needed to replace a weak magneto? Would you have to re lay the crank?No.
The process is basically as you said but you need to get rid of the extraineous info to understand the real process. Set the mag at full advance. Turn it until the points just break. Check which side is firing (this is not like a R60 where both plugs fire at once!) You do this by removing the ignition wire at the mag and confirm the 6mm brasss strip on the bakelite rotor is facing the cylinder you intend to time. Set the piston at top dead center and then turn backwards about 10mm (this is different for the touring and sport models) of piston travel. Install the mag. Done.
Well I give you a B+. Most people don't even understand the questions.
I will tell you there is no less than 100 such questions that all need to be understood to have one of these engines run properly. Are you ready for the next three questions?
Peter D. Nettesheim

[Darryl.Richman]

So, did the casting technology get that much better in the 6 years to the R12 that they could do away with the enclosed bell housing? Or did they find another way to reinforce the rear bearing carrier?

The intake still seems so odd. On later bikes they just took the expedient of pointing the intake backwards. Even when they were selling the M2B15 to other manufacturers, it seemed that this was the standard approach. Victoria, for example, had a short tube, pointed backwards, that openned near the trailing cylinder finning.

Regarding the cam housing bolt, this is similar to the vent bolt BMW began using on the /2s and continued through the Airheads, to lock the speedometer cable to the transmission. That bolt should never be torqued to the standard level that such a bolt is capable of; it will likely strip out the transmission case.

Anyway, what tools do I need to remove (and replace) the camshaft?

As far as Q3 goes, I was just trying for extra credit on the question I understood. If one splits the cases, then one must set up the crank/cam timing first, then go on to the mag timing. I will have the pleasure of getting this right on my R12, when I get back from Germany in a few weeks. The R12 is, to my abilities, much more finicky because of the care and close work necessary to put the timing chain together without dropping small parts into the motor...

Well, if you're giving me a passing grade here, I'm eager for the next test!

[Peter D. Nettesheim]

D,
Just a few quick but no so easy ones
1) Do you have a mag for the r62? The proper one is a Bosch "D" Zunder. The R12 uses the same model but you can't take a magnito from an R12 and use it with the R62. Why? I'm not talking about the chain vs. gear issue. What is the major difference and by looking at the mag (assuming it has no gear or sprocket), how can you tell which one you have?
2)Explain why, unlike a R60, the bosch "D" Zunder only fires one side at a time. Explain why a R60 fires both.
3)Lets say the generator portion of the "D" Zunder isn't charging (count on this one once in a while!). You take it off the bike to check it. How, on the bench, can you determine confidently if its the regulator or perhaps an internal problem with the generator windings or brushes?
Good luck! I expect no less than an A+ grade on this quiz.
Regards,
Peter D. Nettesheim