Now Heres a Stumper!! Anyone ever come across this??!!

[locoleon]

83 xs650..

The bike runs great no problem at all until.... you flick on the headlight then all of a sudden it starts bogging and choking like its just running on one cylinder.

Once you flick the headlight off, it runs great!

Anyone have any ideas?

Thanks

 

[GreasyC]

When you throw the headlight on the voltage is dropping to a level that fails to fire the spark plug. Do you have a multimeter?

 

[ippytattoo]

Have your battery load tested as you may have a weak battery or a weak charging system. I can tell you that on my bike with a PMA if I have the headlight on and hit the horn it will kill it but I am not running a battery I have the Sparx Capacitor from Lowbrow. What it tells me is that the Cap doesn't store enough juice to do both which is essentially what your bike telling you by cutting out.

 

[yamimoto]

83 xs650..

The bike runs great no problem at all until.... you flick on the headlight then all of a sudden it starts bogging and choking like its just running on one cylinder.

Once you flick the headlight off, it runs great!

Anyone have any ideas?

Thanks

I have the same bike which when I got it had the same problem. I agree with the other replies, check your electical system.

 

[locoleon]

THanks gents..
I should have mentioned that it has a brand new battery, as well as a new Reg/rec and new brushes in the stator.

It was charging 13 at idle and 14.5 at 3000 rpm.

I"ll check it with the voltmeter again with:
- the bike running lights off
- the bike running lights on

Now in the event that the volt drops with the bike running with headlight on, any thoughts on where I should be looking?

thanks for all your help!

 

[locoleon]

I have the same bike which when I got it had the same problem. I agree with the other replies, check your electical system.

did you fix the problem? If so, what was the cause?

Thanks

 

[weekendrider]

The US '83 is headlight on all the time from the factory. Is it different for the Canadian models?

 

[locoleon]

No I thinks it's the same.
The PO put in a switch to turn off/on the headlights.
He just put a switch on the ground wire into the headlight.

 

[weekendrider]

Any of the connections grounding?
What happens if you turn the switch on with the headlamp unplugged?

 

[peanut]

sounds like the load on your battery, when the headlight is switched on, is in excess of the charge being put back into the battery by the charging system. Eventually the battery will discharge suficiently for the coil not to provide a strong enough spark.

Your best bet is to disconnect one battery terminal and put a multimeter set to Amps between the battery terminal and the disconnected lead and see what current the bike is drawing from the battery whilst just running and then again when you switch the headlight on.

Either the battery isn't man enough for the load ( mAh rating)or the charging system isn't supplying enough output or there is some sort of short,or bad earth somewhere in the lighting circuit causing a high draw on the battery.

 

[pamcopete]

Try it with the reg / rect unplugged. If it does not bogg down, it's the charging system, if it does bogg down, it's the battery. Could be related to the weak trigger magnet on the rotor.

 

[gggGary]

2nd what pete says; odds are strong it's a replacement aftermarket rotor, on some of those rotors the magnet is too far from the pick ups and a strong charging field causes the pick ups to miss the signal from the magnet. A magnet glued on top of the existing one is a common fix.

 

[XSLeo]

It might still be the battery, even brand new parts can be bad. QA doesn't catch everything. Get it tested. Most places that sell batteries can load test it. Most do it for free.
Leo

 

[locoleon]

Hey gents, I forgot to mention that I put in a brand new rotor from MikesXS

I'll run these these tests and get back to you..

Thanks all!

 

[trance]

maybe you have a short that's pulling power?

try turning off the headlight, then adding a new load straight off the battery. For example, pull the headlight bulb and wire it straight to the battery. If it does not cause any problems, then you can suspect the wiring (rather than the rest of your charging system)

also, try wiring the multimeter straight to the battery and check voltage. See what happens when you turn the light on and off. Shouldn't fluctuate very much.

EDIT: I don't understand putting a headlight switch on the ground, usually it'd go on the hot wire. I bet it's shorting somewhere.

 

[KeithB]

Noel, try what weekendrider suggests by unplugging the headlight and try the switch.
Also, try what others suggest as well.
If you need help, I am in Toronto.

 

[locoleon]

One other thought, I noticed the headlight bulb is a h4 60/55w bulb.

Can anyone confirm for me that the stock bulb should be 40/50w.
Could this be part of the problem?.

Looks like the PO put in a halogen lamp conversion..

Thanks

 

[peanut]

if my calcs are correct that 55watt bulb is drawing approx 4.6 Amps ! if you add the current draw from the rear light and coil etc I would think that you are drawing too much current from your battery . What is the Amp hour rating of your battery ?

 

[5twins]

Many of us run that 60/55 H4 with no problems so I don't think that's it. I have one in my '78 and it's fine.

 

[retiredgentleman]

Remove the switch on the ground wire...............that's a bad way to wire a bike or car.

Have you done some testing with the headlight unplugged? The headlight bulb may be shorted out internally.