Monday, July 27, 2009

X3 stator

OK, so after many evenings of experimentation I finally decided to work on the X3 stator which is the one normally powering my old Kanguro. In previous posts I'd mentioned that this has a 200ohm ignition coil and quite unpredictable starting. The stator is slightly different to those I've been working on as it has the power coils would directly on the stator, no plastic bobbins. The ignition coil is the usual bobbin affair. I decided to leave the laminations on the alloy baseplate as removal is a horrible job, and I have now decided, unneccessary. The copper limiter plates came off easily enough but the plastic seperator was weak, fibrous and broke up as I tried to lever it off. Likewise, the ignition coil bobbin was very brittle and although I managed to move it a little it broke before it was off. The wire inside was a congealed mass, I'm sure the enamel had overheated and, of course, that leads to shorts and a gradual loss of effective turns and this a lowered resistance. The cable insulation is also brittle next to the coils and so that needs to be replaced too.

When I did the original re-wire I left the stator wiring alone and actually handled it very carefully as I was concerned that things might be fragile. It seems than tI wa right to be concerned.

I have a rewound Lambretta ignition coil and so that will be fitted when the stator is cleaned up.

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Remade X1 coil

At last my rewound X1 coil set was ready for mounting. Of course I only set it up with a single power winding rather than the daft 6VDC and 12VAC system.

The ignition coil seems spot on, achieving nearly 200V peak on kick and not oging above 250V peak when running.

However the power coils are not succesful as they produce only 8.4VAC at idle and don't reach 13V until 3000rpm. I'm not entirely surprised as used 1.2mm wire rather than 1mm which seems to be standard on this coil set. Notably 0.8mm is suggested elsewhere for the early 2 phase system.

One thing worth noting is that the cable retaining clip was catching the rotor at first. Then , the outer copper plate was touching and needed to be pushed and filed a little to clear the path. Tolerances are obviously very tight on this setup.

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Tuesday, July 21, 2009

Still winding - power coils

The alternator saga continues. While I'm waiting to get the Indian Scooter stator turned out in the centre I'm rewinding my old X1 stator. The ignition coil went really well, 3000 turns and 307 ohms. I'm also doing the power coils as they were really dirty, slightly damaged, and more importantly, I reckon that with fewer turns of thicker wire I can get more power. That might be wishful thinking but my theory is that the original windings gave an excess voltage. Now that is pointless as the regulator merely wastes everything above 13.8V or whatever, it doesn't 'repackage' it. So with heavier wire I'm hoping to achieve a bare 13V at idle but be able to suck out more current. We'll see. However although I've done the coil set I have discovered that by remaking the coils as per orginal, I've set my self up for messy interconnections. One will have to be remade. At least I'm in the swing of it now.

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Wednesday, July 15, 2009

Too tight!

I assembled the Indian Lambretta stator onto the Morini baseplate with 3mm Alllen headed screws and locking nuts. It looked good and due to the shape of the alloy casting must be pretty well centred.

Last night I fitted it to the engine and all looked good. I even got a few photos of the increased ignition voltage. However as the engine heated up the rotor started to bind on the laminations of the stator. I knew there was less clearance in the centre hole but hoped it was adequate. Basically it's not! As an experiment I tightened the rotor onto the crankshaft and that made it bind in the centre when I turned the rotor by hand.

Unless I can find an easy way to enlarge the centre of the stator, that's the end of that route. A pity as there was significantly higher volts at kick over and idle.

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Sunday, July 12, 2009

Remade ignition coil

I've sorted remaking the ignition coil now. The coil came off the spare X1 stator having shifted the power coils out a little.

The bent over lamination can be straightened with a steel scraper and then pressed flat in the jaws of a vice. The rivets holding the copper 'voltage limiter' plates had to be drilled out releasing the assembly. The black plastic plate cam off with a gentle prise with a steel scraper.

It didn't come easily though, it needed quite a few 'taps' with a hammer and a softwood drift. This did crack it a little (hence the Lambretta/SIL project) but nothing that a little Araldite couldn't fix.

The patent coil machine was put to use and I got 3000 turns on in 40 minutes with a resistance of around 307ohms. As previously, the start and end wires were a little fiddly. I wrapped maksing tape around the coil and then placed some layers of acrylic PCB varnish. Juts to make sure it wouldn't unwound I also ran a bead of Araldite around the former and across the tape joint (not shown on this photo...).

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Thursday, July 09, 2009

A new coil wound

I unwound the Lambretta coil and found tha tit had 4000 turns of wire with an overall diameter of 0.125mm. My task was to put aroudn 3000 turns on to head for a 300 ohm coil. I made a coil winder using a wooden contrction set and a bicycle odometer set to awheel size of 1m circumference. Thus each 'click 'is 1m. It only indicates every 10th click but that tolerance is fine.

It took me best part of 2 hours to make the coil. Remember that it needs a piece of wire connecting at both ends, neat insulation and tape or varnish over the top. I spent longer than I should as I had to re do part of it. The final result has 3000 turns, 330 ohms and looks tidy.

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Tuesday, July 07, 2009

Stator investigations 1

On the MRC rideout I found my Kanguro to be very reluctant to start. It's always had a bit of this habit but I feel it's got worse. The advice of the assembled multitude was that the igntion LT coil on the staor was past its best. It is often advised that the coil should have a resistance of 300ohms, that 180ohms means the bike the won't start and somewhere inbetween is the usual. The X3 coil set in it read 200ohms, so close to the 'failure' level.

I'm setting out to rewind the coil and perhaps remake the whole stator, but before doing that I wanted to know what the LT coil was generating. Here's what I found:

The key findings to me are that at kick over over 100V is achieved which approaches 200V as the engine is revved. The output does not increase evenly with revs - perhaps due to the limiting copper plates.

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