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Discussion Starter #1
Hey all, we've got a 1987 tw200 here, and the headlight seems to get really dim at an idle. At an idle it gives about 1/4 brightness, and it gets brighter and brighter all the way up to 4000 rpm, where it reaches its maximum brightness. I understand that the 87 model has a separate lighting coil, but is it really suppose to be that weak?

The reason I was asking is because the bike comes with a 35 Watt H4 bulb in it, and I was wanting to install a 55 Watt bulb for better night illumination. I was wondering if a 55 Watt bulb would just make the "dim at idle" problem worse, and that's just normal and expected for the 87's, or should I be looking for a problem like a weak lighting coil. I really want to get more light out of this thing!
 

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That seperate lighting coil in the 87's bypasses the battery and runs the light off a/c current. The faster the engine goes the more power is sent to the light. There is a 12 page thread on the topic in here. Yamaha realized this system sucked and changed it the next model year.

You should be seeing 5vac at idle and 13vac at cruising speed

User mcc1776 if I remember right, put in a rectifier and a 20w dc led headlight and was happy. There are some led lights that are compatible with a/c current.
 

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OK, I searched the forum for a thread like this for while, but I couldn't seem to find any, so I made this one. But, this isn't quite like an oil thread though, so I was thinking that another thread on 87 electrical details probably wouldn't be too much. It makes this kind of info more searchable.

I checked the voltage on the lighting coil, and it is 5vac at idle and 10vac at 8k rpm. That seems relatively normal. Will a 55 Watt halogen lightbulb suffer from the low idle voltage more than a 35 Watt? Does the lighting coil even put out enough amps to properly run a 55 Watt light?
 

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I can't answer your question. I have a 99 and 35 watt bulb, I was told to only use 35, not the 55. So I did. But would like to know if 55 will work. Hope an answer is posted.
 

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Here is the link http://tw200forum.com/forum/performance-customization/9239-superbright-dash-headlight.html or http://tw200forum.com/forum/technical-help/2861-87-electric.html

I would think a bigger bulb would be dimmer since it would have a more robust filament.


I remember this from the old forum but it was unclear if it was the headlight, battery or both outputs together

RPM.........Amps........Watts

2000............1..............14

4000...........2.2...........30.8

8000...........3..............42




Newer Model Power Output averaged at 14v



RPM ............... AMPS.....................WATTS

2000 ..................8............................112

4000 ..................13..........................182

6000 ..................14..........................196

8000 ..................15..........................210
 

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Discussion Starter #6 (Edited)
I can't answer your question. I have a 99 and 35 watt bulb, I was told to only use 35, not the 55. So I did. But would like to know if 55 will work. Hope an answer is posted.
Padilen, I am pretty sure you can use a 55 Watt bulb in a 1999 model. The stator assembly has no special lighting coil like the 87; it has a much more powerful charging coil which allows all lights, and blinkers to be run directly off the battery. Anyways, I have a 1998, and run 54 watts of led headlights all the time and it's never been a problem.
 

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Discussion Starter #7
Thanks, Rm_hm, I'd seen that chart too before but I couldn't find it again. So, I'm kind of thinking that a 55 Watt bulb will not work. Oh well, 35 watts of light at night is better than taping a flashlight on my helmet, (had to do that a couple times on an mx bike) so I'll be happy with it.
 
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