DKW SB 200

Motorbike is nearly complete. It was restored before. Unfortunately during this restoration nearly all original screws had been replaced with contemporary screws.A layer of putty and new paint had been laid on old original paint. The motorbike had been also modernized by adding some parts from Avo Simson (FER headlight frame, MAW counter console, back light, headlight glass).

The number on the frame and the label, too, is: 526140. This is the number of KS model from 1939r.

Motorbike is disassembled and parts are evaluated. Now I can roughly tell what is to be done. For example, fuel tanks are leaking; to be welded and sealed. Back seat to be welded, it also needs a new thimble and fastening to the luggage rack. And so on.

All parts good for use are prepared for sanding.

Back wheel hub (Hinterradnabe) is probably from KS model. In SB model the back wheel hub was made of two separate parts (one to be detached when needed) and it had three bearings (Kugellager).

First task when disassembling the engine: detaching the power generator (Lichtmaschine). In the protective lid (Schutzkappe) original connectors are missing. Instead, someone introduced additional cables, running directly from the interruptor (Unterbrecher). Under the interruptor (Unterbrecher) there is textolite pad.

Ignition regulator (Fliehgewicht) needs to be repaired, but it is complete.

Flywheel-rotor (Anker) is in a good shape, So is the commutator (Kommutator). It is not worn. No visible mechanical damage. Power-inducing winding (Feldspule), upper part of the stator (Plus-Poleisen) and brush holders (Kohlehalter) are missing. The motorcycle was ridden without power generator (Lichtmaschine). The only source of power was a battery (Batterie).

The engine (Motor) stopped to work after the shaft wedge on the generator side (Scheibenfeder auf der Ankerseite der Kurbelwelle) had been cut off. There are traces that the Anker had been rotated around the shaft (Kurbelwelle) and the ignition (Zünd) was moved (switched?).

No rust inside the engine. Keine Korrosion im Motor.

First glance at the inside of the cylinder (Zylinderblock). The piston (Kolben) is there. The cylinder liner surface (Zylinderschliff) looks smooth, no visible damage. The engine was running, but it wasn't used much. Cylinder is not worn.

The clutch (Kupplung) is complete.

In the clutch gear (Kupplungs-Zahnrad) one tooth (Zahn) is jagged.

Something bad happened to this engine once, and now the crankshaft drive gear (Antriebsrad auf Kurbelwelle) has got jagged teeth (gezackte Zähne). It would be good to replace this gear with a new one, because the damage can spread when the engine is working again.

Crankcase (Kurbel-Gehause), gear box housing (Getriebe-Gehause) and the lid (Deckel) has been cleaned outside and inside. Threads are fixed and cleaned.

Screw threads (Schraube) have been fixed too and the cases (gehause) are assembled.

The starter roller (Kickstarterwelle) is worn and it needs to be grinded (mahlen). The lid sleeve (Deckelbuchse) to be replaced.

Crankshaft (Kurbelwelle) has been reworked during the previous renovation. Original bearings (Rollenlager+Laufrollen) have been replaced with needle roller bearings, and to do so, the diameter of the shaft had been dimnished from 23mm to 22mm.

This solution has got several disadvantages.

1. There is no way to insert the distance rings (Anlaufring for Rollenlager) so the crankshaft can't be properly positioned

2. The lower bearings get less grease so it's hard to predict how long they last

3. No way to prevent the sliding of the bearings along the shaft

4. The biggest disadvantage: the cones (Kegel) at the ends of the shaft are dimnished to half the size. The result is, the flywheel (Anker) can be easily torn off. This the reason why the flywheel wedge (Anker Scheibenfeder) had been destroyed.

The engine can be assembled back with the reworked crankshaft: it rotates easily, We can put in new gaskets (simmering). The engine is going to run, but it's not possible to predict the durability of this solution. The engine will run until something happens again and we can't know how long it takes.

Other option: to go with the spare crankshaft. First, it should be tried on. In case regeneration is necessary, it could be done here:

Kurbelwelle DKW SB 200 - regeneriert im Tausch » MMM-Ersatzteil-Nachbau (motorradmeistermilz.de)

The gearbox (Zahnrader und Wellen) is complete but one of gearwheels (Klauenrad) has got a broken tooth. Bearings (Kugellar) need to be exchanged.

Cylinder (Zylinderkorper) shows signs of wear but it can still be used. Cylinder inner surface is not damaged.

Piston (Kolben) and rings (Kolbenring) can be used, too. Piston bolt (Kolbenbolzen) is worn in its middle area and it would be good to replace this element.

New pistons are available; we could buy a new piston and have the cylinder grinded. It doesn't seem necessary, though. This piston and cylinder we have got now, they are good enough to work. The big question is, what to do with the crankshaft.

Replacing a piston is easy, if it comes to that. It can be done without taking the engine out from the motorcycle. Replacing a crankshaft is much more difficult.

The motorcycle parts have been sand-cleaned

and painted with anti-corrosion primer.

Rear saddle construction elements are fixed. A new bushing is inserted and the new Roman screw is made. The fastenings to the rack are recreated. Damaged screws are replaced with new ones.

Rims are painted and left to dry:

Frame and front suspension elements have been straightened and fixed.

The missing rear wheel tightener has been recreated.

The frame is reassembled and the geometry is checked:

The central stand has been rebuilt, both straightened and strenghtened. New bushings are lathed for the stand:

Front suspension elements ready for reassembling:

Front suspension assembled:

Front axis elements are cleaned and checked.

The trapezoid damper bolt and friction pads have been made.

A new jaw expander (Bremsschlussel) has been made; the old one was crooked and broken off.

The meter drive was disassembled and cleaned. Sprockets in perfect condition. The bearing bush has been replaced.

The lid is strenghtened and the expander's broken bushing is welded back.

The front hub is reassembled, together with the lid, and checked on the suspension. Suspension distance pads have been lathed and also checked.

Front mudguard has been reshaped. Fastenings are straightened and mounted.

There are two frames for the lamp to choose from. Both frames fit. One of them can be chromed. Another one, after its fastening is recreated, could be painted black.

The lamp glass fits. It can be used, but this glass is from Simpson motorcycle (there is sign at the bottom)

The counter shelf (Tachometer Brett) has been rougly fitted to the trapezoid (this shelf is from NZ model).

There is one problem here: the lamp is from KS model and it is too long, so that there is not enough space for the counter. In SB model the lamp bowl (Sheinwerferkorper) was shorter.

To install the "straight" counter there is not enough space for sure.

Installing the "angular" counter (from AVO) is probably doable after adjusting the shelf. After exchanging the clock face it would look like DKW counter.

The other option is to buy SB lamp on e-bay, a complete one if possible.

The counter (either big or small one) can be also mounted along one side of trapezoid, but this solution is typical for KS. In SB, the counter shelf should be above the lamp.

Here is the shelf: Tachobrille für DKW SB 200 | eBay but this purchase makes sense only when you decide to buy the short SB lamp. It makes no sense to buy this shelf for the long lamp.

Lamp bowl: Vorkrieg Hasag Scheinwerfer Gehäuse Topf DKW NZ SB 250 350 500 | eBay

But we can't be sure we are able to find a proper glass (Glassscheibe), back mirror (Reflector) and the frame, to fit them into this bowl.

Unfortunately there are not many parts available and they are expensive.

The rear mudguard has been straightened and repaired. Aluminum rivets are removed. Cracks and unnecessary openings are welded. Extra rods are welded in, to make the mudguard stronger. The rear rack fitting is replaced.

The main body elements are in place.

There are two steering rods to choose from. Both of them fit.

We will use this one which comes with equipment. Gas lever (Drehgriff), choke lever and all. Everything is signed MILA and it is in good condition.

Cleaned and assembled. The pipe of the steering rod is going to be chromed. Decompressor handle (Dekompressionshebel) is missing. We need to buy it.

The chain guard has been adjusted and fixed. Before painting is done, we need to think about the pump (Luftpumpe). The one which has arrived with the motorcycle is not very vintage. It has got a plastic end.

We could buy this one:

Pompka powietrza Iż, DKW chrom za 43 zł z Kosina - Allegro.pl - (10811156037)

or:

Pompka powietrza Iż,Dkw czarna za 39 zł z Kosina - Allegro.pl - (9221361381)

The rear mudguard fin is fixed. Hinge and rod will be made after the rear wheel is mounted.

The hinge and the lid of the toolbox are fixed.

The passenger's footrests have been repaired.

The elements of the rear axis are a chaos. Many of them had been reworked. The axis together with nuts and distance pads is going to be remade. I will also make new jaw expander (Bremsschlussel) with a lever (Bremshebel).

The rider's footrests have been bought:

New rear hub axis (Achse) has been lathed. At the gear's side there is space for two bearings (Kugellager).

The hub (Nabenkorper), the gear (Bremstrommel) and the cover (Gegenhalteplatte nackt) have been assembled.

Gearbox (Getriebe) and the chain (Kette) are temporarily mounted to check the correct position of the rear hub.

Distance pads (Distanzhulse) nuts (Halsmutter) and pads (Zwishenring) have been lathed.

A new jaw expander (Bremsschlussel) has been lathed.

A lever has been made (Bremshebel) and rear wheel brake is assembled.

The chain cover (Kettenschutz) has been adjusted. The rear fixing has been made.

Should we replace rear gear and chain with new ones?

The battery fittings have been made

In one of two tanks, the bottom part of the tank on the right side is nearly completely destroyed by rust.

The other tank is better: there is a big hole, but just one. This is the tank to be repaired. First the gear lever plate is removed (Schaltsegment).

The destroyed part of the tank's body has been cut out. A new gear lever plate has been made, together with screw sleeves.

The plate has been welded. Next, the tank has been checked against leaking. The weld thread has been covered with epoxy glue for greater safety.

The tank is mounted into the frame and elements of the gear change system (Tankschaltung) have been repaired.

New elements for the steering damper fixing (Arretierscheibe zur Dampungsscheibe) have been made.

The saddle (Gummisattel) has been disassembled. The rear part has been straightened and welded. Screws are replaced.

Sheathing spring (streckfeder) has been adjusted, New rivets/nuts for the gum sheathing are made.

Ready elements are going to be painted now.

The tank has been covered with putty and several layers of primer paint; it is prepared for lacquering.

The horn has been disassembled and cleaned. It is in working state. Another type of horn (smaller one) was used most often for this motorcycle. But this one we have here, this is original Noris. And it works. So we can use it.

The fitting for the horn has been added to the frame.

The lamp (Scheinwerfer) that was bought has been disassembled. Cracked glass (glasscheibe) has been glued. The lamp bowl (Scheinwerferkorper) and bowl edge ring (Einlassiringsring) have been cleaned. All elements of the lamp are original. The reflector (mirror) is in very good condition. It should stay. It would be a pity to discard this reflector and use non-original one.

The lamp is assembled and mounted back. The counter fitting (tachometer-brett) has been adjusted.

The counter (tachometer) which had arrived together with the motorcycle is not good. This is AVO Simson angular counter, it does not fit. We need a straight (non-angular) counter, like the one in the photo. Its diameter should be 80mm (this is the size of the hole in the counter shelf) and it should be scaled to 120 kph, needle turning right.

What can we do about it:

Option one; to buy a counter

This is going to be expensive, and very often original counters are damaged beyond repair when they arrive. The counters described as "after renovation" are not original. They originate from postwar motorcycles. Truly original prewar counters are typically not renovated at all. Instead, the original counter is disconnected from its drive. This is to avoid the risk of further damage.

This counter here seems to be original:

licznik + konsola DKW NZ SB 350 za 3600 zł z Gdańsk - Allegro.pl - (11390322138)

And this one is new (recent production) inside there is China-made drive. But it looks good and it works:

DKW, Auto-Union, SB+NZ 250 350, Tachometer, Ø 80mm, NEU, 120km/h, Oldtimer | eBay

or:

DKW, Auto-Union, SB+NZ 250 350, Tachometer+TW, Ø 80mm, NEU, 120km/h, Oldtimer | eBay

Option two: to use the counter you can see in the photo. I can take this counter I have got here in workshop and change the face, the glass and glass frame. It is going to look exactly like DKW counter. This solution is going to be cheaper.

Rolls in connecting rod base are skewed, due to wrong diameter (Pleuellager is too loose).

The left pin of the shaft (the left side of Kurbelwelle) is in good shape, not too worn. It can continue to work.

The right pin is damaged, Little pieces of hardened upper layer have exfoliated.

The damaged area is substantial. There is no possibility to relocate the bearing to non-demaged area.

Four shaft bearings (rollenlager) are missing. To assemble this engine, somebody has used bearings from another engine.

The kick starter shaft (Kickstarterwelle) has been lathed. A new sleeve (Buchse fur Kickstarterwelle im Gehause) has been also lathed, with a size reserve.

The kickstarter lever (Kickstarterkurbel) has been fixed. A new screw has been made (Linsensenkschraube).

The left side of the engine has been assembled, together with the piston and cylinder. The clutch (Kupplung) is good. The purchased shaft gear (Antriebsrad auf Kurbelwelle) fits well.

The cover (Deckel) has been mounted. A new fitting has been made for the clutch cable (Bowdenseil zur Kupplung) (1.) and the elements of the clutch release lever (Kupplungshebel) (2.). A sleeve is made and welded into the kickstarter lever (Kickstarterkurbel) (3.). A new wedge (Keilbolzen) is made (4.). The oil fill cap (Verschlusschraube) (5.) is fragile due to its age; it would be good to find a replacement.

The parts of the generator have been adjusted to each other. The fastening screws have been made.

New axes have been lathed for the weights of centrifugal regulator.

The winding (feldspule) is fixed. New cables are pulled out.

The generator has been assembled.

The generator lid (schutzkappe) has been fixed. A new circuit breaker (unterbrecher) has been assembled with the best available parts.

The fuse box (spulenkasten) has been disassembled. Joints have been cleaned. The damaged cables have been exchanged.

High voltage coil (zundspule) has been connected. Next, the fuse box (spulenkasten) has been tested.

High voltage circuit has been mounted. The ignition point has been set. The spark has been tested. ,

The head (zylinderkopf) has been found. It fits, but the spark plug thread once was broken and then fixed. Maybe a better head could be found. .

Summary:

The drive shaft fits, but it's not very good shaft. It will be rotating, but it's hard to predict how long it will stand. If more little pieces get detached from the surface under the bearing, they will cause a breakdown. Rolls should not work on damaged surface.

If we decide to renovate the shaft, the connecting rod bearing (Pleuellager) also should be improved.

We need 4 sets of shaft bearings.

I haven't found single gearwheels to be used as replacements in the gearbox. I have only found the whole gearbox.

Carburetor has been detached.

Carburetor is complete and not much used, but one part is damaged. It would be good to buy another carburetor which could be a source of spare parts. Or only the carburetor's body.

According to DKW SB 200 catalog, it should be

AMAL 4/406 carburetor

or

AMAL M74/406 carburetor

Bing in the photo is AJ2/22. We could optionally try to use it.