81 XJ650.... The DIODE IN THE HEADLIGHT BUCKET Problem.

Yes

So would i run a new relay to the white leg of the head light relay. to give it power engage it.

 

you would no longer use the white wire from alternator /diode block set up. and yes the relay would supply power to that pin

 

you could just add a switch light would shut off with key just cut the white wire from diode block and cap it


no added amp draw and if internal diode failed light would still work
and you only buy a switch

 

I will try this. Thank you.

 

You could do that but if the switch works then a good diode block should work. Did you ever check it to see if the diode is shorted in the diode block? Yamaha could have just put a switch in for the headlight, but they made it that way so you don't forget to turn in on, particularly in the daytime.

 

they made it that way due to DOT regulations. many of the euro bikes have an on off switch for the lights.
lights on . cars are drawn to motorcycles with lights on and can not help hitting themfor safety program when it all happened "studys" came out saying turning on a light on your motorcycle caused accidents. moth to a flame thinking cars are drawn to motorcycles with lights on and can not help hitting them was the nay sayers claim. gvt said better to see you with

all the safety circuits were due to regulation. automatic lights, starter safety circuit. had to protect us from ourselves

 

Yes I agree with safety regulations. I not 100% positive but I think it's the same in BC Canada.

I want a quick fixso I can ride. But also will order a diode block to make sure I have a working head light system

Thanks for your help

 

US dot it still would have spilt over to our friends north of the boarder just for ease of production for yamaha

 

So to post an update.

I was able to find another reg/rec to see if that was my problem as I have basically replaced all other components. And I believe a bad reg/rec was the issue.

Funny thing is. I believed that it tested Good.

Anyway I am going to get some insurance and go for a rip.

 

how did you test it?

 

Followed a video on YouTube. But then I could have done it wrong.

 

2 tests one is to check the diodes in the rectifier second is when bike is running see what the voltage climbs up to. if it goes over 14.8 volts at or above 2k rpm is a problem on the airhead xj bikes

 

from what i remember all my tests were good.

I thought I figured out my problem, but my Diode still get hot.

Does anyone know off hand what the wire colors are on their diode block.

81 xj650. Mine are:
white,
white/green,
blue/white,
green,
black/red

I also know that this diode block is not the original one from my bike.

 

measure your diode block the same way you do a rectifier diode check plus 1 resistor.

did you ever try the headlight relay bypass to see if your block still gets hot?

diode blocks are known to have different colors the wires you want to id are the ones from main harness that connect to the diode block.

another question if you remove headlight relay does the block still get hot?

 

I going to check these in the morning

 

So I removed relay and block remained cool
On to test 2

I bypassed relay and diode block remained cool

relay installed block gets hot,
So does that mean relay is no good? To me it seems that the relay is doing its job.
I think some how the diode block is receiving to much voltage or amperage???

For now will run with a bypass till I have time to put in a switch to bypass relay

 

you can open up the relay and clean the contacts. maybe resolder the internal diode that latches the relay in the closed (on) position.

it sounds like you are still drawing amps through the diode block. which could be a bad diode in the relay or voltage drop in the relay causing the white wire to continue drawing amps through the diode block to keep relay closed.

 

you could measure the voltage drop across the relay contacts . measure input side and output side of contacts.