Fråga: Hi, my name is Peter Oetjens. I am restoring a NV20 with Sachs SM51 engine, but I am struggeling with a couple of things.
1. The drive chain is vibrating as hell. In some situations it hits the chain cover hard. In other situations f.e. Around 60km/h it runs quite an smoothly. I have tried out several settings … more or less tension but nothing really worked. What can I do?
2. The rear break lever is mounted so high that I always have to lift the whole foot of the rest to push the lever! Is this position really right? When I try to lower the lever it hits the exhaust. When I try to move the exhaust a bit inwards it hits the main stand. What can I do to improve the situation?
3. I am searching for spare parts. But here in northern Germany I can get nearly nothing. I am looking for a sprockets an drive chain. Also for an complete exhaust and for brake pads.
4. The front brake is really useless, but this seems to be normal. Or is there a way to improve the brake performance?
Best regards from Bispingen, Germany
Peter
Svar: 1. Check the ignition timing. If the engine fires too early, it can make some resonance in the driveline – especially at low rpm. That can make the drive chain move like a string on a guitar. If the problem persists you can glue a thin strip of rubber on the inside of the chain cover to dampen the noise.
2. The position of the rear brake pedal isn’t often the best on older motorcycles. It is very common that one have to lift the foot from the footrest when braking. I think you have to live with it, I’m afraid.
3. The Sachs engine in the NV 20 is made in Germany and I think that spare parts are easier to find in Germany than in Sweden. When it comes to the bike, which is made in Sweden (Uppsala), Sweden is the place to search for that kind of spare parts (wheels, frame, fenders etc.). You can try to advertise in the Swedish magazine Classic Motor.
4. The front brake on smaller bikes from this period are not so good – even when they were new. Old brake linings often loose friction, and that’s worsening over the years. Try to fit new linings on the old brake shoes. Softer linings gives more friction.
Jim Lundberg
