1952 R25/2 project, totally new at this

schrader7032 · Post by **schrader7032** » Wed Jan 27, 2010 5:40 pm

How about that! I just added a '52 R25/2 to my fleet. Mine was built in June 1952. It served some of its life as a police bike in Germany.

For me, keeping the numbers together is important so I would do what it took to keep it that way. Obviously, it might cost. But that's me.

Frame - finding an R25 is one thing...finding a frame would seem even more difficult, unless you could find another severe basket case. I've heard about "The Frame Man" I believe in California. You might try a search of the forum for frame straightening. Possibly some discussions with them could help determine if it's possible to get it straightened.

A question I might ask, is just how important will a perfectly true frame be for an underpowered, less than 70 mph R25/2? I'm betting that it could be straightened enough to make it safe enough.

Engine - again, maybe you can find a donor. You might consider joining the Yahoo Mono club to expand you reach. One of the posters there, Richard, is quite experienced with the singles. He might have a crank. Also, you could check with Dan at Cycleworks. They work with crankshafts, or maybe they did. But they were the only source that I knew of for this kind of thing.

http://autos.groups.yahoo.com/group/bmw-mono-club/
http://www.cycleworks.net/

Cycleworks can also be a good source for tools and other resources to perform work yourself.

For the forum's classifieds, I think you'll heard from the moderator, but you'll need to become a member of the VBMWMO to get to those services. You could try a wanted-to-buy post in IBMWR.ORG's marketplace.

Good luck...I hope you can get it on the road.

schrader7032 · Post by **schrader7032** » Thu Jan 28, 2010 5:05 pm

Just ran across this...Uli's in Germany apparently sells new crankshafts:

http://www.ulismotorradladen.de/englisch/rechts.htm

Kurt in S.A.

Peter · Post by **Peter** » Thu Jan 28, 2010 6:23 pm

Yes Ulis and Stemler in Germany sell cranks and cylinders new; for most vintage BMW's

I think Stemler even sell the frame however it would cost a lot, you can access their website download the catalog and price list for free.

ringerbeem · Post by **ringerbeem** » Fri Jan 29, 2010 9:00 pm

thanks for the replies! I have a lot to tackle. And maybe i should learn some german for that uli site.

808Airhead · Post by **808Airhead** » Sat Jan 30, 2010 12:22 am

Dude,just click the "English/British" flag.........lol It converts it to English.......you owe me a beer now. 8)

VBMWMO · Post by **VBMWMO** » Mon Feb 15, 2010 2:53 pm

I have inherited a 1952 r25/2, mostly together but missing odds and ends. My biggest issue is that i have a badly bent crankshaft and a bent frame( at the front tree mount which looks to have at one time hit head on with something. First with the frame, is straightening it an option? or can i find a donor frame? also with the engine, i am considering finding a donor as well if machining will cost more than its worth. I am not too concerned keeping it matching numbers. This bike has been sitting around for 40 years from my grandfather to my dad now to me; this bike needs to be built. I am reasonably skilled with auto mechanics but bikes are totally new to me.

I am in toronto and i have been in contact with bench mark works Canada but i am trying to save some money and source out what i can myself.

And how special do i need to be to access the classifieds??

ringerbeem · Post by **ringerbeem** » Sat Jun 15, 2013 9:20 am

So after 3 years, I finally have this baby running. Well, it was running. Yesterday is started fine, today, no start. I pulled the plug which was wet, so i dried it off and grounded the plug while in the wire and kicked it over, realizing that there is a weak spark. The batter seems low now because lights and horn are very weak. Any suggestions? Does a weak battery affect the spark?

schrader7032 · Post by **schrader7032** » Sat Jun 15, 2013 10:02 am

Yes, the R25/2 is a battery-coil ignition. No battery, no start...weak battery, weak spark. You probably just flooded the carbs which is understandable as you learn what the bike wants in order to start it. Don't tickle quite so much...if it doesn't seem like it wants to catch, tickle a little more. Be sure your timing is set right as well as the valves.

ringerbeem · Post by **ringerbeem** » Sat Jun 15, 2013 12:19 pm

thanks for the confirmation on the battery, im charging it and i will see what happens. Timing and valves should be fine as it was running when i picked it up from my mechanic who is a vintage bike specialist.

On other topics with my bike, the cylinder head bolts seem to keep losing their torque. Apparently this is due to my head's poor aluminum. We re-torqued them 3 times, now i notice that the bike is burning oil and smoking out the tail pipe at high rpms. COmpression is low but enough to run ok. Could the cylinder head gasket have been compromised after torquing so any times?

I have ordered a rebuilt head from germany as a spare so i will try that one out to see if the alloy is any different

Also, I didnt change the cylinder or the piston because they seemed fine, just changed the rings. Im ordering a new piston and will bore it over soon. The original cylinder being left and honed out could be a culprit for burning oil excessively too so thats why i will bore it out anyways.

Generator:
How do i test the generator to see if its charging at the correct rate? can i use a voltmeter? what is the rate of charge?

Wheels:
Mine seem to be offset to the left side of the bike, both front and rear have similar offsets. Is this normal, possibly for sidecar?

Basically, whoever has an r25/2, please help this newbie with some tips on what to look out for with this bike. My wife wants to kill me already and its only been at the house for a day

schrader7032 · Post by **schrader7032** » Sat Jun 15, 2013 1:24 pm

Well, I have an R25/2 and it's been thoroughly gone over including a recent engine rebuild by Vech.

As for torque, the long bolts thread into the cylinder. With torque being reduced, among other things happening, your valve clearances will be closing up. Are seeing that happen too? If you're losing torque quickly, it's either that the head is squishing or the bolts are not catching in the threads in the cylinder...maybe they're stripped? When I had the engine done, it was initially torqued by Vech. I might have just checked them to be sure. After the first 100 miles or so, I rechecked torque. I'll probably recheck again around 500 miles. But I've not noticed much change in the torque. The head gasket will compress, but only so much. If the bolts won't stay torqued, you probably have some serious metallurgical issues.

To test the generator, the first step is to get a good voltmeter and hooked it to the battery terminals. You should be well over 6.5v, probably closer to 7.0v at the battery with the engine RPM at near cruising speed. Just rev the engine in your driveway while watching the voltmeter. If you're not getting the right voltage, then it gets harder to see where the problem is, but there are checks.

What do you mean by offsets in the wheels? Do you mean that the wheels are not centered between the front forks or under the fenders? They should be. You may have to take some pictures and upload them here.

Not sure what to say to look for. I would be mindful of all fasteners and things attached to the bike. I've had a couple of items depart the bike while underway...the bike vibrates quite a bit and so I try to check things over quite often to be sure it's all still tight.

Good luck!

Vintage BMW Motorcycle Owners