bike stalls at idle when headlight on (PMA w/capacitor)

[ann0yed]

Bike stalls at idle when headlight on (PMA w/capacitor)

When I'm riding the bike runs very well whether the headlight is on or off but when its on and I stop at a light, at idle I can hear the motor stumbling and eventually it stalls. Then I switch the headlight off, and it fires right up. I've got a 50,000ul capacitor, its working fine as far as I can tell because when I shut the bike off, a few things stay powered up for a few seconds. I tried one of those tiny batteries people around here have been using and that worked until I guess my headlight drained the battery of juice and then the same thing happened. Any suggestions? Could I just be running a very power hungry (aftermarket) headlight?


-j


Banshee rotor
VFR500 stator
Pamco Ignition
New wiring harness
50,000ul capacitor

 

[donald]

What is your idle speed ,Maybe you just need to set idle speed a little higher .What voltage are you producing at idle and at 3000 rpm what wattage is your headlight

 

[ann0yed]

I'm idling somewhere around 1200-1500rpm (rpm is represented by bars on my LCD speedo/tach combo), I've tried idling at 2000rpm without much improvement. I will have to get back to you with that other info, thanks for taking an interest in my problem!

-j

 

[ann0yed]

More than a year later and I've got more information. I used a multimeter to check the voltage and its 14 at idle and like 15 or so at higher rpm. When I flick on my 35w headlight there is a BIG voltage drop and the bike stalls. What could be causing this?!?!

Capacitor: Mallory 68000 uF 25 VDC
Simplified wiring done by me, no diagram to show.

Thanks for giving it some thought!

-jonathan

 

[Detale]

Where exactly did you check the voltage? Are you still using the same stator? I've heard guys say that when the it's going going it will give weird readings. Have you tried idling with a battery to see if there's a change?

 

[ann0yed]

Yes, I am using the same stator. I checked at the posts of the capacitor and when I flicked the headlight switch, the needle on the multimeter tilted left quickly registering a big voltage drop. I did run with a tiny battery and capacitor for the last year and the bike ran ok unless the battery was low/dead but have since gotten rid of the battery. The bike idles fine when the headlight is off.

-j

 

[yamaman]

I know some have added a second capacitor, might help?

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[ann0yed]

Well i suppose but is this normal? I don't think it is, I haven't come across this problem anywhere else on this site.

 

[jamesgs4]

maybe you have weak magnets in your rotor? If it was dropped the magnets could be damaged.

 

[ann0yed]

If my rotor had weak magnets would it still generate the same voltage as a normal rotor? I ask because my multimeter reading showed normalcy.

 

[gggGary]

"If my rotor had weak magnets would it still generate the same voltage as a normal rotor"

Sure under a light load, how many watts is the head light? Maybe find a bulb with a low watt low beam filament. For example H4 bulbs can be anywhere from 100/80 watt down to 35/35 watt (a motorcycle special bulb.) Like this one on fleabay
Item number: 360459920996

 

[ann0yed]

Ok, so the general consensus is bad rotor. I will get a new one. Stator, what about that?

 

[yamaman]

Before you go and change anything, it might be a good idea to contact Hugh (punkscaler). Plenty others run 2 caps for the same reason. Pretty 7ure Pamco needs 6+volts to work IIRC.

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[Punkskalar]

That VFR stator is not rated for too high of output, especially without a battery in the system. I'd think that was my culprit.

 

[ann0yed]

Thanks man. I placed an order with you for a new stator and flywheel and am looking forward to leaving this problem behind.

 

[xsbrat]

Hi I'm having a similar problem ditched the battery & fitted the capacitor did a 30 mile run no major issues only fault I could find was when I switch lights on at tickover (harley style 3 position ignition switch), engine dies, ok if you rev engine & then switch (you can hear the engine struggle) & ticks over ok if lights on although dim no problem if riding & you switch on lights. I think the boyer is picking up the voltage drop at tickover when you turn on lights & cutting out, will see if I can live with it if not small moped gel battery.
I'm running a new XSCharge kit, boyer ignition & a lucas capacitor.

 

[ann0yed]

Thanks Hugh, I put your stator and flywheel on and now my bike is producing enough power! Hell, the headlight isn't even dim at idle as it has been since I did my PMA conversion and my horn is full loudness at idle too; I used to have to rev it up to get loud honks! So happy! Now back to the endless carb issues.

 

[Cougar]

Sorry to resurrect a long dead thread here. Just thought it could be of use to someone. I am having the same problem.
With the bike idling at roughly 1500 with the headlight & taillight Iam getting 14.5 V to the capacitor. So I suspect no charging issue there. Idling that high is pretty goofy, especially as the bike warms up it idles a little higher probably close to 1700. If I reduce the idle to say 700 the bike runs for awhile then dies.
I'am suspecting the problem lies in the ignition system. I think the stock points system just requires too much voltage. Any thoughts? I will switch to a pamco system sometime this week and report on how things change.

One quick final question, if using a capacitor and a pamco, is it still essential to shut off the via the key switch? Lets say versus stalling it out. My key switch is in an awkward spot to get to from the riding position.

 

[Punkskalar]

Sorry to resurrect a long dead thread here. Just thought it could be of use to someone. I am having the same problem.
With the bike idling at roughly 1500 with the headlight & taillight Iam getting 14.5 V to the capacitor. So I suspect no charging issue there. Idling that high is pretty goofy, especially as the bike warms up it idles a little higher probably close to 1700. If I reduce the idle to say 700 the bike runs for awhile then dies.
I'am suspecting the problem lies in the ignition system. I think the stock points system just requires too much voltage. Any thoughts? I will switch to a pamco system sometime this week and report on how things change.

One quick final question, if using a capacitor and a pamco, is it still essential to shut off the via the key switch? Lets say versus stalling it out. My key switch is in an awkward spot to get to from the riding position.

Yes, the points have more of a draw than a Pamco. With the points, you'll need to idle up to about 1100-1200 or so. With a Pamco you can idle very low (my engines are rephased, and will idle much lower than stock)

I have a video on Youtube (punkskalar username) of the exact setup you ask about. PMA, Pamco, Capacitor. I run a toggle on that bike instead of a key, but I never flip it off hardly. I just stall out the bike, turn off the petcock and go about my business. Kinda like riding an old dirtbike

 

[Cougar]

Hugh you are a legend.

Got the pamco ultimate in the mail yesterday and put it on.
It idles way lower and can even be started with the lights on now. Seemly more power too. It feels good to know that the only thing left of the stock wiring nightmare is the horn.