Ok so I'm new to the Honda's but never have I seen this happen. I have an 02 and my bike blows the low beam bulb only. I can ride any way I want with high beam on but low beam blows when I give a little throttle. Any ideas on this one?

 

Check the voltage at the light.

If a regulator gives too much voltage, the bulbs will blow.

 

that was my first thought but I thought the headlights were on one not 2 separate ones?

 

you need to check voltage at the bulb while the bulb is connected, unloaded voltage isn't necessarily a useful measurement

excess resistance in the bulb circuit can blow the bulb (or at least cause it to get a bit too hot and it'll blow as soon as vibration hits it).

corrosion in the socket? bad contacts at the starter button?

the headlight harness is pretty wimpy too, maybe a wire has given up the ghost. the factory ground splices in that harness are also super weak. you might try adding a second ground to the low beam just to the frame or whatever to see if the problem goes away.

on the f4i, the high beam goes through a relay, and the low beam is direct from the ign. switch (if you think about it, it's probably just so there's near zero load on the high/low beam switch). so the low beam might have a crapload of resistance but the relay is solving that problem for the high beam...

also just fyi, don't ever touch the glass part of your headlight bulb... and don't buy cheap chinese made h7 bulbs, their vibration resistance is poor.

 

Ok so I checked the voltage key on engine off and get about 14.5 volts. Started the engine let idle 19.6 and at 5k rpms it spikes up around 20-21 volts.

Resistance shows an open loop either way with the key on engine off or engine running. With the key off I am getting right at 100 ohms and slowly dropping.

I'm not a wiring genius or anything close very small scale wiring jobs so any help?!?!?

This is no bulb cause I don't like throwing 20 bucks away haha.

 

R/R is done....

It's blowing bulbs because they can't take the voltage. It should be no higher than 14.5 and high rpms.

If you keep running it with the system voltage that high, other things will get as well.

 

Ok I didn't know if it would be the stator or the rectifier. Voltage jumps like that would be in other areas of the system as well though correct?

 

You can check the stator, but you will probably find that it's good. A bad stator usually puts out nothing, not 20v.

 

Well just put a new r/r on order so hopefully this will be finished/fixed soon. Thanks everyone for the assistance.