Runs better with the headlight on

[atomic22]

Alright, I've searched and can not find a similar post. If you know of one please point it out.

My bike is running very rich and I think it's a electrical issue with the bike running so crappy. I can get it started easily enough, but it runs really rough, however, when I turn the lights on (a separate switch) the bike smooths out, still not running great but a noticeable difference.

PMA, kick only, headlight and taillight only. I am running a 12v 2.9f mini battery. I'm willing to add a full size battery, but to me it seems weird that when I turn on the lights the bike runs better.

Could the battery be bad, something with the grounding, or bad rec/reg? I'm really lost at this point. I've spent a lot of time on this bike, and I've been chasing electrical demons for years. I've cleaned and re-cleaned the carbs.

Any thoughts?

Thanks in advance.

 

[retiredgentleman]

PMA's generate full output (varies with rpm) all the time. When they produce more current than the load can use, the regulator directs the excess current to ground. Double check that the regulator is connected to a good bare metal ground on the frame.

The regulator may be having a hard time trying to keep the voltage below 15 volts, when the headlight is off. Bikes and cars don't run well when voltage gets over 15 volts. Solution...................leave the headlight on all the time to provide more load.

The small battery may not be a good match. Try using a larger battery.

It may be a good idea to measure the voltage at the battery terminals at idle and at 3000 to 4000 rpm.

 

[atomic22]

PMA's generate full output (varies with rpm) all the time. When they produce more current than the load can use, the regulator directs the excess current to ground. Double check that the regulator is connected to a good bare metal ground on the frame.

The regulator may be having a hard time trying to keep the voltage below 15 volts, when the headlight is off. Bikes and cars don't run well when voltage gets over 15 volts. Solution...................leave the headlight on all the time to provide more load.

The small battery may not be a good match. Try using a larger battery.

It may be a good idea to measure the voltage at the battery terminals at idle and at 3000 to 4000 rpm.

OK, I'll try that. now that you mention the regulator not being grounded properly, that may be the culprit. I'll check that. My thought process is:

1. check regulator ground
2. replace battery
3. replace rec/reg

Anything else, anyone can think of to check?

Thanks retiredgentleman

 

[ridgerunner1965]

id sure want to know the voltage running.if your showing 15 volts instead of 13 or 14.sumpin you got a prob.

 

[atomic22]

Thanks guys I'll take a look at it in the next couple of days and report back my findings. Any other suggestions are still welcomed.

 

[gggGary]

try before you buy jumper or bodge on any old lead acid battery of a reasonable size see how it acts.

Before we can say much beyond that, what ignition, carbs, air filter pipes are you running? Way too many times we have danced the dance only to find out on post #150 that it's got the original points wires and coils, 6" straight pipes, mike's PK carbs bought used off ebay and no air filters and coat hanger wiring. Well not all at once but you know? A few pics could be so useful. You know I never did see a pic of that frame part installed.....

 

[goat315]

I'm dealing with a 1977 that does the same thing..in fact if you turn the blinkers on the RPM's go up & down. if I manually kick off the voltage regulator it dies immediately,,,WTF ?

 

[retiredgentleman]

I'm dealing with a 1977 that does the same thing..in fact if you turn the blinkers on the RPM's go up & down. if I manually kick off the voltage regulator it dies immediately,,,WTF ?

Not enough information here. What type alternator and regulator are you using? If you are using a battery, is it a good battery and what size is it? What do you mean by" kick off the regulator"?

How much does the rpm change?

 

[atomic22]

Well I figured out my problem was the voltage reg/rec was not grounded properly. I ended up bolting it done better and runs like a top...with the lights off or on.
Thanks for all the help...again

 

[atomic22]

try before you buy jumper or bodge on any old lead acid battery of a reasonable size see how it acts.

Before we can say much beyond that, what ignition, carbs, air filter pipes are you running? Way too many times we have danced the dance only to find out on post #150 that it's got the original points wires and coils, 6" straight pipes, mike's PK carbs bought used off ebay and no air filters and coat hanger wiring. Well not all at once but you know? A few pics could be so useful. You know I never did see a pic of that frame part installed.....

I might put that information in my profile for my posts.

As for the part I used it and then i had to redo the whole bike, so it's no longer on the bike. I used it to match both sides of the frame. The 81 has this funky little curve on one side, and I made them match.

 

[goat315]

Not enough information here. What type alternator and regulator are you using? If you are using a battery, is it a good battery and what size is it? What do you mean by" kick off the regulator"?

How much does the rpm change?

it has the OEM stator & regulator, rectifier is aftermarket. the rectifier was installed before the bike was brought to me but supposedly ran fine for a while. this bike is kickstart only & has a good 14L-A battery. I'm kicking off the regulator by manually breaking the contact in the reg. with the headlight on it will run semi decent up to 3000 RPM...turn the blinker on & it bounces around 200 RPM up & down . noticed the coil on the bottom of the regulator gets real warm Fast. the voltage is 13 1/2 to 14 1/2 volts while running. without the lights on it wont rev much over idle