| Daytona Sprinter 50cc Dim Headlamp Investigation |
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| 50cc Daytona Sprinter (made in Greece) with 110cc engine fitted so that it can climb hills. | |
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| Not wanting to remove the entire plastic skirt each time I needed to access the wiring, I made a sawcut (yellow arrows). (Red arrow indicates a repair that I made after the bike toppled onto my knee and broke the plastic tabs.) |
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| Note how dim the small bulb is. The headlamp bulb is also dim as you can tell from the orange glow. |
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| The setup I squeezed the bike into my tiny workshop and connected the oscilloscope as shown in the picture below this. |
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| The oscilloscope probe is connected to the yellow wire that connects magneto output to the regulator. The oscilloscope "ground" is connected to the green wire (chassis). I pushed two long, narrow bolts into the plug to make the connections. |
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| Oscilloscope set to 1 volt per division. The probe was set to divide by ten so each vertical division (1cm) on the oscilloscope screen represents 10 volts. The photo shows the negative-going partial sinewave whose peak varies up to about 15 volts when the headlamp is on and engine is running at 3500 rpm. Notice that the peaks vary in height. Not stable. Does that small peak indicate a weak magnet? If you average the peaks the result is equivalent to about 5 volts max. YouTube video link: |
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| My guess at what's inside the diode/regulator block (blue). and... Wiring Diagram PDF ( skema ) |
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| Original factory wiring had joints made by twisting wires together. The copper was still bright but I was unhappy with this method and fitted crimp connectors instead. Below: a view of the wiring. Near the centre you can see the CDI (Capacitor Discharge Ignition) unit. This was hanging loose as the rubber band support had snapped. I fitted a metal band. To the left of the CDI unit is the high voltage coil. |
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| At present December 18, 2018 I still don't know the fault cause but the magneto (generator) is prime suspect. |
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| December 20, 2018 I measured the battery voltage with the engine idling and it was around 13 volts, rising to 14.8 volts at 3500 rpm. With headlight switched on (still dim) the battery voltage still measured above 14 volts. Makes no sense to me but I decided that the magneto is certainly good enough to charge the battery. I modified the wiring, disconnecting the yellow (unregulated) lighting feed from the regulator output and connecting it to the red (regulated) output from the regulator, which goes directly to battery positive. Lights work fine but battery voltage is around 12.5 volts even with lights off. I'm confused! I'm going to leave it like this and see if the battery maintains its charge and hoping that the regulator doesn't die with the additional load of around 45 Watts (4 Amps). |
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| My first attempt wiring modification. The headlight switch now gets its power directly from the battery (+). January 9, 2019 - First sunny day for over a week. |
| OK, that seemed to work but it flattened the battery, even with the headlights switched off! I discovered that somewhere on its way to the lighting switch, the yellow wire changes to yellow-white. So I suspect that there's something connected that isn't shown on the circuit diagram. I put the wiring back to normal and had a rethink. I removed the plastic panel over the front wheel. I traced the yellow-white wire going to the lighting switch and the black wire coming from the ignition switch. | |
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| I cut the yellow-white wire (Y) from the large, white connector at the left of the picture and fed it into a (blue) Scotchlock connector (filled with silicone grease). I placed this connector over the black wire (B) and crimped the connector down. So the lighting switch now gets its feed from the ignition switch. With the ignition switch off, there should be no drain on the battery. This should work provided that the regulator can pass enough current to charge the battery with the lights on. I've ordered a different regulator and bridge rectifier, just in case it can't. I've also ordered an LED headlight bulb that will require less current. |
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| While waiting for the LED headlamp bulb, I made some LED "telltale" bulbs to replace the filament bulbs, which are too dim. These are polarised and must be fitted the right way round in the bulb holder. I can now see the "telltale" glow from the indicators, main beam, neutral, etc. I've also replaced all three nighttime illumination bulbs in the speedometer pod with LED bulbs. |
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| Note: the purchased-from-China LED bulbs failed (intermittent), possibly due to corrosion, so I replaced them with waterproof LED bulbs from a different manufacturer. We had a couple of hours of sunshine so I dismantled the bike and installed a voltmeter. I had to fit a shroud (made from a plastic lid) because I couldn't see the digital display in sunlight. |
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| January 18, 2019 Today we had fine weather and, while in town, I found a shop selling LED headlight bulbs. So I bought one for 6 Euros. Back home, I fitted it to the motorbike. It seems to work OK and the battery voltage is good. |
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| Result! Nice bright, white headlight and the battery still charges adequately. NOTE: the LED bulb is polarised so you MUST modify the wiring before changing the bulb to LED type. |
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| A few days ago I noticed a burning plastic smell when I stopped. It was coming from the front of the bike where I'd made the wiring modification. The smell disappeared by the time I reached my destination. It was a cold day and I wasn't prepared to investigate. January 19, 2019 A warmer day. I noticed that the plastic fairing was loose because a plastic tag had snapped. On closer inspection it was obvious that the plastic had been touching the exhaust pipe, close to the engine. I had found the source of the burning plastic smell. An unused bracket with tapped hole was next to it so I made a metal link and scrwed it in place to secure the plastic fairing. |
| As for the regulator, the mystery deepens. As the yellow wire from the regulator is no longer connected to the lighting switch, I disconnected it close to the regulator. The result was that the battery voltage never rose above 12.5 volts! | |
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| Another fault that I had was that the "TOP" gear telltale lit in 1st gear, not 4th. The mechanic had connected pink to pink from the gearbox, assuming that this was correct. I found three unused wires exiting the gearbox and measured their resistance to ground as I changed gear. I have labelled them 2, 3 and 4. I connected "4" to the pink wire for "TOP" so now I can tell that I'm in 4th gear at a glance. (The bike is still geared for a 50cc engine so I'm continually trying to change up! I'll change the sprockets eventually.) Also, when I get around to it, I'll extend the three numbered wires to the speedometer housing and I'll fit LEDs for all the gears, just for fun. |
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| The new regulator finally arrived from China. I mounted it on a piece of aluminium with a bridge rectifier and two 4700uF capacitors. Everything seems to work perfectly! Even with the lights on, it provides a constant 13.8 volts, except at very low revs. |
| The (underrated) capacitors overheated and exploded so I reverted to the old regulator and ordered a standard "universal" replacement. | |
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| When it arrived I fitted it and the battery now charges with the lights on. |
| We had a week of rain, after which the bike wouldn't start. I traced the problem to a float chamber full of water! | |
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| I'm not sure how it got there but, as you can see in the photo, the new* air filter is a basic wire mesh device, which is immediately behind the front wheel. I suspect that the plastic fairing above it fills with water spray every time I ride on a wet road. The air filter probably sucks in water. I don't see how it would get into the float chamber but I'd like to protect the carburettor from water anyway. The gap between the air filter and mudguard is about 1.5 cm. I guess I'm looking for a rubber inlet hose with air filter box that could be mounted higher. *Had to use this because the 110cc engine sits further forward than the original 50cc engine, leaving very little space. |
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| My local bike mechanic came up with an idea. He had a plastic housing off something. He fitted wire mesh inside and put oiled foam rubber on top of it. |
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| Cap fitted to the lower half of the moulding, trapping the foam rubber inside. |
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| Fitted to the carburettor. It seems to provide good airflow while keeping bugs and grit out. Whether it keeps out water remains to be seen. I'd like to fit a curved hose to its inlet. (I did so later.) |
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| The fuel gauge started "playing up". The needle was bouncing between empty and full except when the tank was completely full. I had no idea how much fuel I had left. I dismantled the handlebar fairing and discovered a loose wire on the back of the fuel meter. I tightened this, congratulating myself on fixing the fault so easily. |
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| But the fault prevailed! After more testing, I determined that the tank sender unit (rheostat) was faulty. I removed it from the tank and bent the "slider" contact to increase its pressure. This helped a little but it was still not right. Luckily, I managed to find an almost identical unit on eBay and placed an order. |
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| When it arrived I swapped it with the faulty one. I had to bend the float wire to adjust the meter reading but fitting was quite easy and the supplied cable with plug matched the socket on the bike. I was glad that I'd made the sawcut in the plastic skirt because the socket was behind it! |
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| I decided that the headlight was still inadequate, even with the LED "bulb" fitted, so I ordered a pair of LED spotlights. When they arrived, I fitted them to the handlebar fairing. I fitted a toggle switch and connected that to the lighting circuit (below) |
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| I ordered a weatherproof switch cover. Actually, I ordered two, which is just as well because the first one broke as I was tightening the threaded plastic ring with pliers! |
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| In addition, I have an optional rechargeable cyclist's head torch mounted to a quick-release bracket in between the spotlights. NOW I can see the road ahead! A couple of days later, the bike died as I was setting off. I discovered that the 10 Amp fuse next to the battery had melted. The headlight circuit originally ran from a separate magneto feed so running everything via the battery-ignition feed was just a bit too much. I replaced the 10 Amp fuse with a 20 Amp fuse. The wiring seems to be OK. Fingers crossed! |
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| While riding, I realised that the spotlights were vibrating and rattling loudly, which was very irritating. I removed the fairing and made steel plates, which I fitted inside beneath the nuts that hold the spotlight brackets. These plates stiffened the plastic to minimise vibration. To cure the rattling, I screwed a short piece of perforated steel strip to each side of the fairing. (This strip is called "tserki" in Greek and comes on a reel.) It doesn't look pretty but it did the job. No more rattling! |
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| Bike with spotlights. Join the Q. |
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| August 16, 2019 This morning I found petrol dripping underneath the bike. A quick inspection revealed that the pipe between fuel tank and filter had perished and the end had split. I clamped the pipe with a mole-wrench, cut off the damaged end and refitted it to the filter with a new stainless-steel hose clip. Then I removed the mole wrench. No more drips! |
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| My "Daytona Sprinter" is actually a scooter that is built with plastic panels to make it look like a motorbike. The original voltage regulator simply didn't work properly. It had a built-in half-wave rectifier and was useless. So I bought a generic motorbike regulator and modified the wiring to fit that. However, its output voltage was too high so I had to keep the headlight and spotlights on while the engine was running and, even then, the voltage was around 14.6 volts - too high for continual charging. You might recall that I bought a different type of battery charger and added a full-wave bridge rectifier plus a large reservoir capacitor - which became too hot after only a kilometer. So the project was put on hold. |
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| I had previously made a successful conversion of a battery charger to bench Power Supply Unit by using a bank of 2200uF capacitors to share the ripple current. I decided to use the same idea. So here is the regulator assembly (2) on an aluminium backplate with bank of capacitors (3) and bridge rectifier (4) wrapped in Blu-Tack. The older regulator (1) is left in place in case I need to revert back. (5) see below. |
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| I went for a run to Georgioupoli. As there are no tourists, a lot of renovation and building work is being carried out. The regulator failed! I had to swap back to the previous one. But I've figured out why it fails. It has no protection from the back EMF from the battery. When the battery voltage exceeds the regulator output, the direction of current flow reverses and "pop". It needs a rectifier in series or input-to-output. But in series a rectifier will lose a volt so I would need a 15 volt regulator to compensate. Thinking about this! |
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| The speedometer pod has an indicator light for 4th gear and one for neutral. However, the gearbox that came with the latest engine (now 130cc) has wires for all gears (#5 in previous photo, above). So I fitted three LED bulbholders to the speedometer pod, which already had holes for them, and connected them to the wires (#5 in above photo), with a length of 3-core mains cable. This PVC sheathed cable has to run above the engine in a position that gets wet and warm, so I threaded it through a length of sturdy plastic tube for extra protection. |
