Exhaust decoke

 

Remove the exhaust silencer endpiece by removing the nut inside. The end section then pulls off and teleases the tube tree inside.

Remove the trlube tree. Scrape any of the sticky deposits you can reach from inside the silencer and inside the end cap. Clean the tube tree I find DPF cleaner works but paraffin also helps. Its a nasty disgusting job however you do it.

Reassembly is the reverse but note the rope seal in the recess at the end of the main silencer (in the groove where the end piece fits) and do not damage or remove it as you clean! Secondly the silencer never seals onto the down tube and exhaust always leaks here. I seal the joint with Curil or Vital copper RTV- but silicone would also work.

Shock Absorbers- damper overhaul (also Quickly TT)

I've already covered removing the shock absorbers from the front wheel and noted that they had little if any damping action. They are clearly going to need attention. In fact replacements are available for the front at 66Euro a pair which I thought was quite good- but sadly no such luck for the rears- these will have to be overhauled. I decided to investigate how to do this using the fronts which are effectively disposable since I have ordered replacements. The first few pictures just recap how to disassemble the shocks to release the dampers but this is described under front end strip.

Lock the two nuts up against each other and gripping the top one only in a vice unscrew the damper shroud (CLOCKWISE)

Grip the end of the damper rod with a small screw driver as it becomes inaccessible in the shroud and keep screwing the shroud right off.

Invert the shock in the vice and tap the end cap off using a screwdriver

Rest the shock horizontally (dont grip it) and push the grey lower shroud upwards  to slip the black sleeving off

Remove the sleeve

remove the black sleeve and also the stepped ring that sits inside the grey lower shroud

Then looking inside the grey lower shroud-locate the snap ring in its groove about halfway down the damper and spring it out with a fine screwdriver.

The grey shrouds then slide off the assembly below shows all these components except the grey shrouds.

Snap ring removed from damper groove shown after the grey plastic shrouds have been removed.

Looking at the top of the damper you can see an internal snap ring that holds the damper end cover in place. 

Remove this snap ring- its quite difficult but best option is to use a very fine screwdriver or a sharp pointed  probe to get behind it and ease it out of the groove. You may need two such implements- one to lever and one to slip behind the ring to stop it popping back home. In extremis you can cut a very SHALLOW groove in the end of the damper just down to snap ring height so you can lever it through the slot again using a fine screwdriver but be careful  to cut no lower than the snap ring groove

Whoppeee- its out

The damper end cap isnt held tightly and just lifted off with a magnetic probe.

This revealed the radial seal beneath which acts as the barrier to keep damper fluid in. Its a tight fit and I was unable to find any non-destructive means of removing it. Obviously this seal has to mate smoothly with both the damper rod and the inside of the damper tube so levering is not a good idea- scratch either surface and you can expect oil leaks. Luckily new seals are available from Krippl at 10 euros a piece. 

The seal actually incorporates a metal washer for rigidity- I exposed this in my attempts to remove the seal.  This was an old component and there was no flexibility in the rubber at all- it just cracked off. As you can see the rubber actually surrounds the damper rod and its possible to very carefully insert a fine screwdriver...

... and lever the seal upwards. If doing this again I think I would just drill a hole through the seal and insert a probe to lever from there

The old seal then slips off up the damper rod exposing the discs beneath. These are held in with a circlip- but in fact I'm hoping that this is as far as I need to go and that just cleaning and refilling with fresh oil will restore function. 

I cleaned out all rubber debris above the brass discs and then was confronted with this upper circlip.

Using circlip pliers compress the internal clip whilst pulling upwards on the damper rod. The upper brass bush will slip out...

... fallowed by the rest of the rod assembly and lower rubber seal and base bushes.

When I emptied the damper the oil that came out was black. Since the unit is completely sealed the only source for this dirt has to be wear on the rubber bush- certainly it had a dull, worn-looking appearance. I'd like to change the lower rubber. This looks feasible after removing the E clip at the base of the rod. However new rubbers for this position are currently unavailable, so Im pinning my hopes on a clean and refill.

The complete rod assembly is shown above. It consists of 3 brass bushes  a rubber bush and at least 2 telescopic tubes. I couldn't work out how it works but it obviously pushes oil around.

I cleaned all components including inside the damper tube and then started the  reassembly. The capacity of the damper is around 45ml so I measured 25ml of straight 10W fork oil and poured that into the tube before carefully lowering the damper rod assembly into place.

I found that by gently moving the rod up and down I expelled air and the oil level fell- top up again and repeat etc etc. Eventually I got to the point where both the rod and most of the oil fitted inside. I could slip the upper brass bush down whilst compressing the circlip. Note that there are several locating grooves inside the damper tube- so make sure the brass is down at the right level and has room above it for the seal.

I then fitted the new top seal- you need to remove the oil above the bass disc so that the seal can fit. This meant pulling out another 5ml so the dampers were probably filled with 35-40 ml in total 

Finally I refitted the seal cap and its circlip. The rest of these pics show the reassembly of the shock and are here mainly for my reference. I have to say that the improvement was only marginal and in the absence of any new rubbers for the base of the damper I think it might be useful to move to thicker oil so if I rebuild the second damper Ill try straight 20W to see if it helps (obviously Ill replace the oil in the first if it does).

The only points of note in the rebuild are firstly that if you are using new dampers from Krippl, note that these come with 2 circlip grooves- perhaps so they can be used on different bikes? Compare with the old to determine which groove should be used. I found it was the upper.

The second point is that the parts diagram shows the spring base fitted upside down. The spring seat has a flat and a stepped side. The step is a perfect fit for inside the lower shrouds- it doesnt fit inside the spring and so cant act to locate it as shown in the parts book. Mine were fitted with the flat side up when I stripped them so Im rebuilding them this way.

Changing the points

Contact breaker points used in the Quick 50 are also the same as the type 2 points used in some NSU Quicklies. They are held on by an adjuster screw which can be loosened to adjust the gap, and a spring clip on the central pivot post.

Remove the adjuster screw 

Contact breaker mounting screw.

... and lever off the retaining clamp.

Before removing the points note the order of components on the moving point electrical contact screw here indicated with a screw driver. These are 5 and 6mm sizes, but its really hard to remove the points until the wires are removed  because the wire length is insufficient. An extra 5cm  would have worked wonders for convenience here!

Remove the moving point by lifting it off the central post. NOTE the order of attachment . From inside the points towards the exterior the order is 

Bolt head, moving point leaf spring, insulating washer, Fixed point, insulating washer, electrical contacts (2 wires in this case), washer, spring washer, nut.

New points

It is REALLY difficult to attach the wires and washers to the electrical contact bolt. This is fitted in such a way that there is too little slack in the wires and you're forced to try and fit the various washers etc using fat fingers crammed into the space above the lighting coil. Since the bolt hangs downwards from its head through the fixed plate, any loss of grip on any of the components allows them to slip off the vertical bolt. I recommend placing a tissue in a tray beneath the bike whilst trying to fit the points as you WILL drop them and if they are allowed to bounce you will spend hours looking for tiny washers. I found this process pretty much impossible but eventually twisted the points and wires so that the bolt was horizontal before attaching the wires and then rotated it back into position, allowing the wires to slip round as I did so. It did work but did lead to some strain  in the wires like a spring. Make sure the electrical contacts to the moving point do not contact the horns of the lighting coil beneath which are earthed. Mine did come quite close- closer than Id like. Compare the pictures below with the fitment of the original points and you'll see what I mean. This arrangement does work but I may have to revisit it to address this spacing later.

Fixed point installed and connected

Add the moving point and re-clip it into place.

Adjust the gap.
 

Reassembly

 

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Reassembly was pretty much a reverse of dissassembly with a couple of remarks.

Firstly, I had to reduce the brim thickness of the sw arm bushes to 1mm each to allow the washers to be slipped in between bush and frame. This also gave a good swinging fit with no play and aligned nicely with the circlip.

Secondly although the parts book shows the rear mudguard as fitted with 4 15mm M6 bolts, only the top 2 are of this type. The lower 2 are self tapping hex screws fitting into captive nut plates.

Rear mudguard fastenings-hex self tapping lower mount on left, 15m.m6 on right.

I fitted a plain washer and spring washer under the top two and plain washers under the lower.

Remember to feed the rear light cable through the mudguard before fitting the mudguard itself.

The rear tyre was split and unusable so I fitted a new tyre and tube. I cleaned and re-lubed the chain before refitting the rear wheel and chain.  Rear wheel chain tensioners adjusted easily. Pleased that the sprocket does accept the chaun monkey alignment indicator so wheel alignment and chain tension were sorted at the same time. I could then refit the chainguards. Very pleased that now I had knocked the dents out of the chainguard the 2 halves fitted perfectly around the sprocket and overlapped each other very neatly. 

Coming together- moving on to exhaust and frame cladding

Remove the carb and rubber mount before fitting the frame cladding. I realised that the wire and cable runs originally on my bike may well be wrong- and engine cladding plates were missing. I found I could feed the handlebar wiring loom down inside the frame cladding to emerge in the groove above the motor. The wiring from the alternator could also be fed into this groove so that the connections are made inside and covered (eventually) by the engine cover plates. I'm still not sure I've routed the clutch able correctly but this will be obvious when I fit the engine cover plates...*

*In fact this proved to be correct - the clutch cable enters the top of the LH cover plate. The RH plate actually has a cut-out to allow the magneto wires to take this route.

Wiring exits base of frame cladding to make connections to magneto in central groove.

Wiring enters top of frame cladding- clutch cable stays free.

Connections hidden in groove, make sure all connections are insulated.

Exhaust and motor covers fitted

Note motor covers require 2 countersunk m6 machine screws, 15mm and 30mm.

Left cover, kick start and gearchange levers fitted.

Fitting kickstart and gearchange levers- note that the kickstart has 1 large spline that must be aligned with that on the stub shaft. Note the clutch cable entering via its cut-out in the motor cover.

Exhaust fitted- I did buy the correct ring nut from NSU.de. Note the magneto wiring entering motor cover through deficated cut-out at front right

Exhaust fitted- the chrome on this was largely protected by the grease and cleaned up well. Those areas which were too badly pitted were treated and resprayed with a mist of hammerite.

Detail exhaust end cap and brake cable.

The bike was now coming together at a pace but I remembered I had yet to finish the fuel tank which I had eventually had to strip to bare metal and sprayed white. I used fine line tape to mark out the grey areas and then masked off the rest begore spraying.

Respraying colour panels on tank.

I gave the white paint plenty of time to harden before masking, and then sprayed the panels one at a time to avoid getting it wrong... again!

The tank plate screws had been damaged so I replaced them with 6mm M3 countersunk screws.

I have the badges to go back but I need new 6mm M3 countersunk screws.

Tank badges reinstalled... needed new 6mm m3 countersunk screws.

Tank trim still to go...