Saturday, September 22, 2012

1956 Csepel Danuvia 125 - Update

In my previous post about my recently acquired Csepel Danuvia, I had mentioned that in the process of trying to find an oil leak on the clutch side of the engine, I discovered a few other minor problems. The oil was leaking out of a bad seal on the gear shift shaft, but when removing the gear shift lever I found that the splines on the gear shift lever and gear shift shaft were completely stripped. In addition to the stripped gear shift splines, the threads in the engine case for the gear oil fill plug were completely stripped. The plug was just sitting in the hole. One other thing that bugged me was the kick start lever had kind of a sloppy repair. There is kind of special style bolt that holds the top part of the lever on that was missing and somebody had beat the stud that it fits on with a hammer until it mushroomed enough to hold the lever on. In addition to that, there were some broken or worn stops for the rotation of the top lever piece that someone had tried to repair by welding blobs in their place. When kickstarting the lever rotated to far backwards making it easy for your foot to slip off the kick starter.

I've probably said it a thousand times but thank goodness for the internet. I was able to track down the parts I needed fairly quick. I received the parts I needed last week and began to put the bike back together.

Well actually before putting it back together I needed to repair the stripped threads in the engine case with a heli-coil.

This was a rather expensive thread repair. It's a M16 x 1.50 thread. It might have almost been cheaper to find another case.

 While I had been waiting on parts I did a few other things like cleaning the carb, new spark plug, changing some of the wiring to look a little more period correct, and just general maintenance and tweaking to get everything the way I felt it should be. With the threads now repaired, I finished putting the bike back together. The morning after I got it all back together, I put fresh gas and gear oil in it and rolled it outside. It fired up on about the third kick. Boy was I a happy guy. I rode around the neighborhood for a little while. Not venturing too far since I don't have tags for it yet. The other reason I was happy is we've had a brutal summer in the midwest. It's finally cooled down and I was excited thinking I was going to get in some beautiful fall weather riding on my Csepel. Well, my excitement was kind of short lived. Later in the evening my wife wanting to see the bike running. As my wife was watching me ride, the clutch began to not work correctly. Uh oh, better bring it in and figure out what's wrong.

Having just put the bike back together on the previous night, I was now taking it back apart to figure out what was wrong with the clutch. As you can see in this photo, the very outside plate of the clutch is made of a bakelite (plastic) type material, and it had begun to break apart. The missing pieces of this were scattered in the bottom of the clutch case and gear box. Oh well, back to work on the Isetta while I'm trying to find a replacement for this part. 

*UPDATE - Since disassembling the clutch I've learned this bakelite disc did not belong in a Csepel. It is probably out of a Simson motorcycle. I guessing somebody used it as an additional spacer because the 5 cork clutch plates that were on the bike were wore very thin.


  1. The clutch material seems odd, they are made of cork on my '60 danuvia 125.

    1. Yes, it did not belong in a Csepel. I was told it is probably from a Simson motorcycle. The original plates with cork were wore quite thin and I guess somebody used the bakelite plate as a spacer. I just got a new set of clutch plates in the mail today, so hopefully I'll have it back together in the next day or two.

    2. What type of gear oil did you use in the engine case? I've heard different opinions on the type/weight to use on these older engines. Modern oils have additives that improve lubricity that weren't avail in the 50's-60's, and could effect clutch function. As far as gas/oil mix, 32:1 synthetic would probably be safe. The original manual called for 20:1 !

    3. I'm using Bel-Ray Gear Saver Transmission Oil 75W and Bel-Ray MC-1 Full Synthetic 2T Oil. The MC-1 is suppose to be specifically formulated for vintage 2-stroke motorcycles. It sounds lean but MC-1 is formulated to be run at 50:1 and Bel-Ray recommends against running it any heavier. I haven't ridden the bike enough to formulate any kind of opinion yet.