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Voltage spikes on throttle- ‘74 TY250


ConnorJohn
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Hey all, 

Hoping I can get some replies here! I’ve have a ‘74 TY250 for about a year. Took it out for a single ride other than up and down the road and around the property (moo), it was so much fun. Can’t wait for the upcoming season.

two questions:

1. i purchased it for $1300. It came with an entire other bike’s worth of parts. Wheels and tires, gas tank, etc. All except the engine that was destroyed when it got wrapped around a tree. What’re your thoughts on that price for the bike and parts? I thought it was a steal.

2. I get voltage spikes on throttle and keep blowing bulbs. I replaced the condenser, contact breaker, and spark plug today and the thing fires up like it’s brand new.  But still experiencing the voltage spikes. Any ideas? Maybe I’m just dumb and incorrectly wiring the lights, but also fear it could be something more systemic. Would bad magneto coils lead to this or would the condenser catch that? Any tips for trouble shooting this would be greatly appreciated.

best from Montana,

Connor

IMG_3988.jpeg

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It's 6 volt is it not? adding a capacitor in this case 6 volt that will smooth the voltage spikes, you could add a rectifier if you want to make smooth DC and if the voltage is not right you add voltage regulation on the nice smooth DC output then you can even set it up for LED or low voltage incandescent.

In the olden days it was done with a Zener diode which was a cheap and easy way to both regulate and rectify voltage, might be one of those on there now or should be, wiring diagram would tell.

... yes awesome price the OEM headlight if perfect is too valuable to leave on for serious riding.

Edited by lemur
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19 minutes ago, lemur said:

It's 6 volt is it not? adding a capacitor in this case 6 volt that will smooth the voltage spikes, you could add a rectifier if you want to make smooth DC and if the voltage is not right you add voltage regulation on the nice smooth DC output then you can even set it up for LED or low voltage incandescent.

In the olden days it was done with a Zener diode which was a cheap and easy way to both regulate and rectify voltage, might be one of those on there now or should be, wiring diagram would tell.

... yes awesome price the OEM headlight if perfect is too valuable to leave on for serious riding.

Thanks! I ordered a regulator/rectifier, LEDs would be sweet. I appreciate your reply!

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1 hour ago, ConnorJohn said:

Hey all, 

Hoping I can get some replies here! I’ve have a ‘74 TY250 for about a year. Took it out for a single ride other than up and down the road and around the property (moo), it was so much fun. Can’t wait for the upcoming season.

two questions:

1. i purchased it for $1300. It came with an entire other bike’s worth of parts. Wheels and tires, gas tank, etc. All except the engine that was destroyed when it got wrapped around a tree. What’re your thoughts on that price for the bike and parts? I thought it was a steal.

2. I get voltage spikes on throttle and keep blowing bulbs. I replaced the condenser, contact breaker, and spark plug today and the thing fires up like it’s brand new.  But still experiencing the voltage spikes. Any ideas? Maybe I’m just dumb and incorrectly wiring the lights, but also fear it could be something more systemic. Would bad magneto coils lead to this or would the condenser catch that? Any tips for trouble shooting this would be greatly appreciated.

best from Montana,

Connor

IMG_3988.jpeg

Yes that is great value. They are a fabulous motorbike.

The ignition system is not connected to the lighting system. Each has its own stator coil in the magneto.

Blowing 6V bulbs was standard back in the day for TY250A. Fitting 12V bulbs was one way to avoid it, but the lights then became dimmer. They came with no voltage regulation on the lighting circuit so as the RPM rises, the voltage rises.

Nowadays there are a myriad of options for the lighting circuit on motorbikes.

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