Restoration of BMW R69s engine

[mattthemuppet2]

I think the problem too is that if you try to get better than the factory specs you've obtained you may end up chasing your tail, where one adjustment changes a value elsewhere, and fixing that one changings something else. I see it in building bicycle wheels - when the spoke tension gets high and the runout low, trying to reduce the runout in one place causes problems somewhere else. Whenever I see that start to happen I stop and call it good.

 

[malmac]

I think the problem too is that if you try to get better than the factory specs you've obtained you may end up chasing your tail, where one adjustment changes a value elsewhere, and fixing that one changings something else. I see it in building bicycle wheels - when the spoke tension gets high and the runout low, trying to reduce the runout in one place causes problems somewhere else. Whenever I see that start to happen I stop and call it good.

I had better take that on board not only with this but especially when I get to rebuilding the spoked wheels.
Thanks for the advice. It seems like good advice.


Mal

 

[malmac]

Well lots of distractions have slowed progress and this year looks like being a lot of run arounds and not much restoration work.

The crank is finished and finally within spec.
So now I have to sort out the flywheel for runout.

Now this flywheel is the correct flywheel for this engine but is not the flywheel that came with the engine.
So this will be a voyage of discovery.

First I had to make some bearings for the trueing stand.



Then attach the flyweel to the crank and start the checking process.



So more head scratching because the first quick spin was not a perfect or near perfect score.

Mal

 

[malmac]

They say never give up. Well I keep plugging away at this rebuild.

Today I had to modify some reproduction oil slingers so they fit as required.

Here is a composite image that I hope tells the story of the press tool I turned up to get the fit I wanted.

Unfortunately I forgot to snap a pic of the press tool in the hydraulic press at 2000psi.

Cheers.


Mal

 

[C-Bag]

They say never give up. Well I keep plugging away at this rebuild.

Today I had to modify some reproduction oil slingers so they fit as required.

Here is a composite image that I hope tells the story of the press tool I turned up to get the fit I wanted.

Unfortunately I forgot to snap a pic of the press tool in the hydraulic press at 2000psi.

Cheers.


Mal

View attachment 355309

This is definitely one of those times where I’m sure this all makes sense to you and I see the change but have NO idea how this works and what it is other than an ”oil slinger”.

 

[juiceclone]

I had a ‘72 R75/5 with a Vetter fairing. I loved that bike, especially the incredible engineering. When i saw the header I had to check because if it was a BMW car I wouldn’t care, not at all a fan. The old BMW air cools, very cool. Had no idea it was so heavy on the special tools though. I also was a VW air cool fan and it didn’t take a 1/10 the specialized equipment.

Had a German Hercules JB-K in the 50s. Everything was perfectly fitted. The head was so well designed it required no gasket! But u gotta put it back together with the same care!!

 

[malmac]

Had a German Hercules JB-K in the 50s. Everything was perfectly fitted. The head was so well designed it required no gasket! But u gotta put it back together with the same care!!

Was your machine something like this one.

A really pretty machine.
Even has Earles type front forks.

Very nice.


Mal

 

[malmac]

Well the time has come for the crankshaft to be put back into the crankcase.
I like to carefully measure everything to, as much as possible, avoid the need to pull the crank in and out because I have overlooked some basic clearance issue.

I draw up the crank and crankcase to scale to theoretically calculate the shim/spacers required for the best fit fore and aft.

 

[malmac]

Started to put together some parts for the engine. Good to start assembly.

If you are familiar with these BMW models you will know that there is a lot of interference fits. Parts in the oven other parts in the freezer and then press together.

 

[C-Bag]

Had a German Hercules JB-K in the 50s. Everything was perfectly fitted. The head was so well designed it required no gasket! But u gotta put it back together with the same care!!

The old VW air cooled had no head gaskets either.