R25/2 Engine Teardown

I'm documenting my teardown on the Vintage BMW website in case you want to follow along.

[url]http://www.vintagebmw.org/v7/node/8763[/url]

This is my '52 R25/2 that I purchased two years ago. It has an unknown maintenance history, so after about 850 miles, I figure I know enough about the bike but don't want to push my luck with the slingers getting full.

You don't have to be a member to see the thread, but would have to join the forum to post anything. Membership in the Vintage club allows access to the members-only section of the forum.

I had an R 26 (3 by the time I was done with that obsession) and on my first ride on the first one the motor locked up about a mile from home. Well I did a complete tear down to get a new(used R 50)connecting rod installed at the local Harley shop. I am still amazed at the fact that I accomplished the job(successfully)using only a Butler & Smith parts catalog, a couple hand written notes and a lot of incredibly dumb luck. I remember using the oven and the freezer to reinstall the crankshaft on the same night my roommate was having a house party, she was not very happy that my motor rebuild in the kitchen and garage was the life of the party. She was rather upset that an engine block was baking in the oven with snacks and a crank shaft was getting chilled in the freezer next to the frozen Margarita mix. I still have the home made connecting rod that had caused the motor to lock up. Have fun and enjoy the journey.

"This is my '52 R25/2 that I purchased two years ago. It has an unknown maintenance history, so after about 850 miles, I figure I know enough about the bike but don't want to push my luck with the slingers getting full."

Very nice bike, Kurt! Must be way cool. I'm still working on my r27; nowheres near the panache!

Thanks...I hope to get the engine out of the frame this weekend. If I'm lucky, I'll begin pulling the topend off.

I haven't been posting here much...but things are up to date at the above link. I'm basically done pulling the engine down, now just cleaning things up.

Interesting find in that the cylinder is 1st over already, so I'm not the first to do this. The piston has a mold date stamp of "2 63" so it was probably done late during the police ownership (1957 - 1970). I'll have to confirm that if I can ever get records from Germany.

I checked the ring gap...all basically right at the maximum if not a little over. That might explain some of the poor performance...we'll see. If I'm lucky, I can just get the cylinders treated at Bore-Tech and rering without having to go to the next oversize. I'll wait to see what Vech says.

[url]http://bore-tech.com/[/url]

Bore-Tech provides a carbide treatment, in the same vain as the Nikasil treatment of the early '80s Airheads.

Well, the first part is done...I'm returning from a road trip to give the engine to Vech for rebuild. It certainly cost more in gas and motels to drive the parts to him but the knowledge that the parts arrived safely...priceless! Plus, I had three days off from work!!

It'll probably be middle of the summer before things get finished. Vech said he'd send the head off to Memphis Motorwerks and the cylinder and piston will go off to Bore-Tech. The crankshaft will be examined for dimensions...if necessary, it will go off for repair as well.

Now it's just the waiting!!

I got some pictures back yesterday from Vech's shop...they were able to get the bottom end apart. Interesting observations...the slinger was fairly empty but the main bearings were really nasty looking. So, it appears that someone was inside the motor since it was produced to clean the slinger but maybe reused the main bearings. The crank is in good shape so no rebuild needed there. Follow the link above to see the latest pictures.

I drove to Vech's over the past two days to pick the engine up. Here's the link to the finished engine pictures:

[url]http://vintagebmw.org/v7/node/8763?page=page=2#comment-20373[/url]

...well I thought that would go to the last page...guess not... :dunno

Now I have to figure out where that frame is!!

That thing's pulling your bumper off, Kurt!

Thanks for posting; good essay.

[QUOTE=rinty;813287]That thing's pulling your bumper off, Kurt![/QUOTE]

No wonder my back is hurting me...I had to lift it out of the back seat of my car! :lol

[QUOTE]...had to lift it...[/QUOTE]

Oh, you don't want to be doing that.

I lifted a roll of carpet into my neighbour's dumpster; saved $50 on the haul fee, and spent $200 on physiotherapy for my back. Luckily, it was just muscle issues.

Check the last page of the thread to see the progress today!

[url]http://vintagebmw.org/v7/node/8763[/url]

Well, maybe just kicking tomorrow. I got everything together, had to deal with a porous deep sump which was exchanged, and rechecked the timing. I'm going to put some "fresh" air in the tires and see if she'll light up tomorrow.

You kicking already this morning?

Kicking, and kicking, and kicking! She just needed some foreplay! Took a bit but at first, no joy. I had to do the usual - check for fuel, check for spark, etc. I felt good about the timing. Everything looked good. Finally, there was a rumble and then she started.

Took her out for about 15 miles, riding the access road near my house. I had to duck into the turnarounds when the light changed on me. I cut it somewhat short as the play in the clutch cable began to get too big...made it hard to shift...I need to recheck that.

I also noticed some backfiring on decel, so will need to recheck the timing.

See you after noon!