mikey

Mikey's '57 NSU Prima D

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Figured someone may be interested in my NSU I rebuilt a couple of years ago.

Day one:

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Getting there:

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It runs:

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Finished, it looks nicer than it really is:

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This thing hasn't been on the road for around 3 months which has been tearing my nut-sack because I've had to drive the car to work and pay for parking, or forget to pay for parking and get many tickets.

But no more! The old duck is back!

Instead of a alternator it uses a dynamo which is kinda rad 'cos it doubles as a starter motor, but kinda stink cos it's weird as fuck and uses an electro magnet (field winding) instead of a real magnet.

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But mine wasn't charging it's battery cos of a gnarly short around one of the brushes.

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I had a backup dynamo so figured I'd just use the case from that with field windings attached.

Still didn't work so I figured the short musta busted more stuff. After replacing the dynamo armature, dicking about with the brushes and buying a solid state regulator from the UK, I discovered that my replacement field windings were buggered from the start.

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So my only option was to repair the original dynamo brush which had shorted and blown out hard.

Bodges ensue:

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The fuel cap on this thing has never sealed properly and it leaks two-stroke everywhere which is great anti-rust but it turns dynamo brushes into cutting paste and generally pisses me off.

So I finally fixed it; pulled a filler hose from a Holden something at pick-a-part and welded it in.

I thought I'd never weld a tank but I just had to fix this leak, it's been pissing me off for years. Flushed it with soapy water a few times, filled it with water and welded away.

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It's 4 million times better than before but there's two pinholes in the welds, anyone know what to seal with? I chased the welds where the pinholes were but it didn't really help and from previous experience it's bloody hard to use weld to fill the little fuckers.

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POR 15 tank prep.

its perfect for those little pin holes.

and those fags at Scooterworld have it! /can do it for you.

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This morning I put 3M seam sealer over the weld, apparently it's fuel resistant. Hopefully that'll suss's it. Otherwise POR15 FTW.

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The seam sealer failed at sealing the tank. But JB weld worked a treat. Yay.

On to the next leaky thing! I replaced the Bing carb with a Dellorto PHBG. Which is frrcken sweet compared to the leaky old one.

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Made up some new cables for the choke/throttle. Did a skid!!! Nah! Not really, this thing is the opposite of skids.

But words can't describe how good it feels to have a scooter that doesn't leak two-stroke everywhere I park it! Ha ha.

This is the dynamo controller/regulator I hooked up

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Also has new coil (thanks 10speed) and new battery.

Next things on the list is new tire and fashion some hold down springs for the front brakes. It's a gamble every time I use the front brakes at the moment; one in five times the shoes wont be parallel with the drum and the front wheel locks up, and front springs bottom-out and go BANG!!. It's a terrifyingly exciting senario...

This is the other thing I'm working on. Digital ignition with programmable advance. I'm using a BIP373 ignition driver, PIC16F628 micro and hall-effect sensor. I've _almost_ got it working! I've been battling to fire the coil without destroying transistors/micros. This is about the 4th revision of the ignition circuit. Anyhoo, shouldn't be too far off I reckon!

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Main motivation for this is because points for this thing are impossible to get these days and my current ones are super fucked. It's rideable (I rode it to work today) but you can tell the timing is all over the show!

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what kind of industrial stationary motor grey did you paint those engine parts with?

Also (although it involves less creativity) did you consider tapping some bolt holes and running different points?

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what kind of industrial stationary motor grey did you paint those engine parts with?

I'm pretty sure it was Duplicolor rattle can grey. I _might_ still have a can sitting at home I can check.

Also (although it involves less creativity) did you consider tapping some bolt holes and running different points?

Nah, I didn't really think of that. That's probably a much easier option than the witchcraft I've come up with! It doesn't appeal to the nerd within thou.

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Because Lockdown, I've pulled this out from the pond under the house. It's been there for about 4 years making close friends with some rust and spiders and mold. 

Last time I was bumbling around with it it had a couple of issues. The biggest one was the Dynastart, which is a dynamo that you can also use as a starter motor. It worked once in a blue moon, so I'd have to crash start it. So that's top of the list. 

Other things to fix; the front brakes lock-up when the front suspension starts compressing, this is great lols. The timing advance seems beyond repair with rust, I'd like to move to electronic ignition. The wiring/switch gear is pretty ropey. 

Some dust:

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More dust:

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Some rust:

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YAY

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Oh, if anyone has some suggestions for some sort of electronic ignition for a single cylinder that has timing advance and just works off the battery i.e doesn't involve adding extra coils please let me know. 

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13 hours ago, mikey said:

Oh, if anyone has some suggestions for some sort of electronic ignition for a single cylinder that has timing advance and just works off the battery i.e doesn't involve adding extra coils please let me know. 

@Raizer @Poo

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So. Pulled the Dynastart field windings apart and found they were oil soaked & shorting to ground. 

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Tidied up, replaced all wires & bushes & sorted out the rust. The points look a bit shit, but the contacts are basically new. I fixed up the auto-advance too, so will stick with points for now. 

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I could feel a bit of "backlash" in the flywheel, turned out to be a shagged small end bush. Spare parts are hard to come by, but I had a spare engine so recycled the bush out of it which was still in spec. A bit agricultural, oh well. 

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Bore is okay.

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Getting the engine in is fricken impossible, it weighs a tonne and she's a toight fit. After a lot of sweat and swearing I found doing it upside-down is more doable.

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Gear change bowden cables were bunged up, lucky I have a luberer

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Went for a blat round the block and pumped up the tires. The engine feels good. The front brakes are still terrifying.

And I can't find third gear, that's always been a tricky one. Will make new cables, but I actually think the mechanism is from a different bike. 

 

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So.... dem brakes.

They look simple enough, but something ain't right. With a light touch on the brake lever they grab hard and the front springs bottom-out violently.

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This is all the tech info I have.

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I suck at drum brakes. I really really do. HALP!!

There's no signs of anything weird from what I can see. All I can think of is that maybe the drum grabs the leading edge of the shoe and spreads the shoes so they grab harder?

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Oh, those pads were replacements put on by Sterling Brake & Clutch about 9 years ago. The original ones are riveted, these are bonded. 

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It was as simple as glazed shoes :smurfin: I just hit them with a Scotch Brite pad and brake cleaner and now they feel great :flower: What a muppet. I figured glazed shoes would cause the opposite of grabbing, which is why it took me so long to work this out :reindeer:

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