DKW Engine Progress

I have made some progress on the DKW engine build.  It's been a fun process, but I have run into a few "issues" here and there.  But nothing I couldn't overcome.

Step 1 was reassembly of the clutch.  Top photo shows the assembly back together.  Middle photo shows it being assembled.  Getting all the "teeth" on the discs and basket lined up, while keeping the springs in place was sort of comical.  And realize this entire assembly is about 3" in diameter, so lots of fiddly little parts.  The third photo shows the entire assembly spread out.  Like other moto clutches, this uses a series of discs and steel plates, that all clamp together.  This way you can fit more clamping area inside a small diameter.

Then I got some of the internals installed into one half of the engine case.  I had to buy a few NOS parts, including a new 1st gear, new layshaft, and of course all new bearings and seals.  Doing the bearings was actually kind of fun.  Stick the cases in the oven for a few minutes so they expand a little, and slip the bearings in with a little bit of pressing.  Then as the cases cool, the bearings are nice and snug.

I took a lot of photos during disassembly, which was good.  The factory engine manual is very helpful, but in a weird 1970s translated german to english sort of way.  So a few sentences are confusing, and the terms they use for various shafts and shims made me scratch my head a few times.  But everything went back together fairly easily.

The only real problem I ran into was there were apparently many different types of 1st gears, which was the only gear I need a replacement for.  The original had a tooth knocked off.  My 5-speed engine needed a 106-100 part#.  The guy I bought the NOS parts from accidentally sent me a 106-200, which looks identical.  But when I finally got around to fitting it, I realized it must have been a 1st gear from a 6-spd trans, as it was thinner.  Luckily my source down in LA sent me a correct gear asap.  But when I got it, it was labelled 106-000.  It was the correct thickness, but the back side of the gear was lacking a small chamfer cut into.  Without this chamfer, the backside of the gear lightly rubbed the aluminum case on the inside.  Long story made even longer, my new little Mini-lathe came to the rescue.  I chucked it up, and was able to cut a light chamfer into it, so it fit just fine.

At this point, I pulled out my NOS gasket kit.  As the seller mentioned, the gasket we're laying very flat anymore.  He didn't charge me much for a full kit, and it included the seals too, so I was expecting to have to recreate a few new gaskets.  The big center case gasket was indeed shrunken a little bit, making it so that all the bolt holes were not lined up.  So I scratched my head, and set about making a new gasket.

I used a spare wooden shelf board, and marked and drilled all the case bolt holes into it.  This way I could stick the case bolts through it, based on their real position using the case as a guide.  Then I carefully stretched the NOS gasket over the bolts, and marked around it.  Then I trimmed the new gasket out with a razor, applied a tiny bit of permatex to one side of the case, set the new gasket on it, and let it sort of bond for 30 minutes.  This helped it lay out flat, and kept all the holes in position.  The last step was to turn that side of the case upside down, and fit onto the case half with all the gubbins in it.  I was expecting this to be a pain in the arse, having to line up multiple shafts, multiple case holes etc., and fight a gasket lining up.  Reality was it just slide down and fit easy.  Sorry for the random order of the following four photos.  Sometime blogger has a mind of its own.

DKW Update - Free the Sprocket!

For no reason in particular, I stalled out on the DKW project.  I got to the point where I needed some engine parts, in order to reassemble it.  After much inspection and measuring, I found the cylinder bore needed a bore job, I need a new piston, and I couldn't for the life of me get the sprocket off the shaft.  It is a press fit onto a taper, held tight with a large nut.  Apparently they like to weld themselves to the shaft.

I soaked, I heated, I soaked, I hit it with a hammer, I soaked some more, I installed a large puller pounded as tight as I could get with my 1/2" impact.  Nothing.

Then...as luck would have it...I came across a guy in Reseda selling NOS DKW/Sachs engine parts.  This was roughly four days before Christmas, and Susan's youngest Sister happens to live in Reseda, and was coming up for a visit.  So I struck a deal for a new cylinder housing that cleaned up very nicely, a NOS piston kit, a NOS sprocket and nut, and a NOS set of points.  All for the same price a DKW specialist shop sells just a piston kit for.

So the old seized sprocket had become redundant, and I decided drastic measures were in order.  That meant getting out the angle grinder, and going to town on it.  10 minutes later, and a face and mouth full of grinding dust later, I was able to finally remove the sprocket, and pull the shaft out of the engine case.

So now I'm soaking the engine cases to help de-grime the past four decades worth of grease, oil, and dirt.  One of the pain in the asses about heavily finned air-cooled engines, are the deep fins that collect all kinds of debris.  I'm half tempted to find a local machine shop to dunk the cases in, before I give them a wire brushing and polishing.

Then, I need to order a set of bearings, seals, and gaskets for the re-assembly.

Exciting photos below proving I did do some work:

DKW: Shiny Seat

I made incredible progress on the DKW seat.  I kept putting off the "shaping" of the aluminum, since it can be a huge pain in the arse to cut.  Cutting wheels get gummed up, this 1/16" material is a bit too thick for my small shears etc.  After applying some masking tape to mark the cut lines, I discovered the thin abrasive cutting wheel on my angle grinder cut through it like butter.  No gumming up, no galling, no crazy super hot burr.  The masking tape must provide some sort of lubrication in this process, because it was a million times easier cutting it with the tape, versus when I cut it without the tape Saturday.  Lesson learned!

After that, I wet sanded it with 1000 grit and WD40, then 1500grit, then 000 steel wool.  Then I installed my new 6" buffing wheel on my angle grinder, and dug out the white rouge I had sitting in my file drawer for the last 15 years.  I've never really polished aluminum before, as I really like the look of the 000 steel wool left on previous projects.  So I wasn't sure what to expect with the buffing wheel and rouge.

What I got was an instant and very easy polish job.  Like maybe 5 minutes total was spent on the wheel, with light pressure.  I topped it off with some Meguires AL polish on a terry cloth towel.  The polish is great, and matches the tank well.  You can still see some of the marks left from the extruding process, so I could always do some more sanding and a re-polish if I feel like it.

I gave the seat a bit of a coke bottle shape.  Thinner at the front, wider in the middle, then tapers a bit at the back and has a cutout for the under seat mounted exhaust.  The three screw holes at the back will be used for mounting the taillight assembly, which I haven't even fabbed up.   

Last bit of good news: The stock length kickstand appears to work perfect at the ride height I intend to run the bike at.  And the new custom springs I sourced seem to be just right.  Some cafe style bikes have low and hard suspension, which looks great.  But all of our immediate streets have such shitty bumps and potholes, I've discovered softer it better for normal riding.  So I took a bit of a gamble on some springs from McMasterCarr, and I think it has paid off.  

DKW 125 Gas Tank Petcock M12x1mm

Sorry for the attention grabbing headline.  I've realized my blog subject lines make for good google searches, for obscure shit like petcock sizes on motorcycles.  In this case, the petcock size for a 1971 DKW 125 Boondocker is a M12x1mm thread.  Happens to be a very common moped size, so I picked up two part# 50294 petcocks from 1977mopeds, which fit a Honda Hobbit.  Perfect fit on the DKW.

As you can see, I've started assembly work on the bike.  Spent the past few weeks painting and polishing and cleaning up random parts.  Trying to take my time.  As such, I've discovered the back porch to be a much nicer place to fiddle than in the garage.  I can eat lunch outside, and spend 10 minutes doing odd jobs.  

The petcock money shot is at the bottom.  

New Tools and DKW Work

I splurged on a few new tools for upcoming projects. One is 1/2" sander that worked great this morning. Very easy to use in tight spots, easy to change belts on etc.  

I also picked up a load leveler, which I'll be using as an engine hoist for pulling the motor out of Freddy, in preparation for swapping the transmission. Seems fairly robust, and just the right size.  It's also adjustable so you can tilt the engine one way or the other while it is suspended, in case you need to wiggle it a little bit.  My old "hoist" for the FV motor was a pair of straps, and any wiggling meant wiggle by armstrong, whilst trying to keep things from crashing about.

I haven't posted much about the DKW project, since I've been working on Freddy. But this weekend I finished up all the welding and metal cleanup. It will only require s little bit of body work to fill in a few nicks and scrapes. The new 1/2" sander worked great for getting into tight spots.

DKW Engine Removal

Snatched the motor out of the DKW this morning. It had a little water in it, but hopefully enough trans fluid to keep demon rust from forming. The brown milkshake was fairly clean, and easily washed off the clutch side of the engine.

Combustion chamber shows signs of abuse, and the piston is a bit tattered around the top ring land. Pin came out easily enough, and the small end needle bearing looked great.

And either the intake ports have been ported, or ze germans did some clean up work at the factory.