Are you sure that is a regulator rectifier and not just a regulator? The output might be AC, if that is the case a capacitor will do you no good.

 

More importantly, I need to borrow your ATK for a couple years.

 

The voltage drop with increase in throttle is normal. As revs increase, demand for power increases to fire the plugs more often. My RS250 does the same thing.

I'm also pretty sure the output is DC, so it is a regulator/rectifier. Otherwise, the entire ignition system would be different in design, and the LEDs wouldn't work.

Find a wiring diagram online for the R, and compare it to your wiring. They should be fairly similar, if your statements are correct. Cut and add the cap in your harness where the battery would have been located, had the L come with one.

 

...and [MENTION=22826]RedKat600[/MENTION] in 3.....2.....1
He'll know the answer.:secret:

 

A capacitor is not the same thing a battery because the capacitor has the ability to continue to accept voltage increases up to the breakdown rating voltage of the capacitor used; as a result, I think it can smooth out the charging system generator ripples but will not limit the maximum voltage across the capacitor as a battery could?

"NEVER pull the battery cable to check the alternator. This very crude test method was marginally OK when we had vacuum tube car radios and point-type ignitions, but it is a very bad idea now. The battery stabilizes the electrical system and loads the alternator, preventing high peak voltages or voltage surges as the alternator adjusts magnetic flux to produce the same average voltage at different current demands. If you rev the engine up and pull a battery cable, the alternator voltage can spike up to 100 volts or higher before the alternator flux dies off enough to bring voltage back down to 14 volts or so. This can kill the car's computer and other expensive electrical components. I've seen headlights blow out when a guy opened a battery switch while an engine was revved up. If you hear anyone telling someone this is a way to check an alternator in a modern vehicle, stop them!"​

See http://www.w8ji.com/battery_and_charging_system.htm

Maybe a small amp-hour rated lead-acid or AGM battery might be a better choice than just a capacitor, that is my opinion.

 

I put a sealed lead acid battery on my dirbike to run some lights and horn without dimming anything.. my regulator/rectifier had a dc input and output to hook a battery into, so it would charge my battery most of the time or draw from the battery when extra power was needed.

Also, AC will run LED lights. only while the power is in positive.. which happens 60 times a second usually.. depending on the hertz. A capacitor would not work off AC voltage, so best find out what you have running though your bike..

"NEVER pull the battery cable to check the alternator. This very crude test method was marginally OK when we had vacuum tube car radios and point-type ignitions, but it is a very bad idea now. The battery stabilizes the electrical system and loads the alternator, preventing high peak voltages or voltage surges as the alternator adjusts magnetic flux to produce the same average voltage at different current demands. If you rev the engine up and pull a battery cable, the alternator voltage can spike up to 100 volts or higher before the alternator flux dies off enough to bring voltage back down to 14 volts or so. This can kill the car's computer and other expensive electrical components. I've seen headlights blow out when a guy opened a battery switch while an engine was revved up. If you hear anyone telling someone this is a way to check an alternator in a modern vehicle, stop them!"​

See http://www.w8ji.com/battery_and_charging_system.htm

Motorcycles do not have alternators.. also how is that even relevant?

 

Diagram shows that it is a split system. Both AC and DC. Looks like there is DC purely for the blinkers and horn.

XR systems have a dedicated coil on the stator to the run CDI and ignition coil. So reving the engine should not cause additional draw on the lighting coils. ALL of my XRs when revved will make the lights brighter.

Now a failed regulator will do that. That is how my HaHa Designs regulator failed. Rev the engine and the lights would nearly go out.

 

Diagram shows that it is a split system. Both AC and DC. Looks like there is DC purely for the blinkers and horn.

XR systems have a dedicated coil on the stator to the run CDI and ignition coil. So reving the engine should not cause additional draw on the lighting coils. ALL of my XRs when revved will make the lights brighter.

Now a failed regulator will do that. That is how my HaHa Designs regulator failed. Rev the engine and the lights would nearly go out.

So will a bad battery. My 1984 Big Red 200 does that when the battery is flat.

I'd start with a regulator check. And add small battery or capacitor to the system after the problem is diagnosed.

 

I don't have an oscilliscope, but I do have a multimeter. That diagram posted by toastybake sure looks like it. I'll compare it sometime this week and figure something out. Thanks all! Interesting discussion indeed.

 

I'm wondering if the regulator is simply a SCR controlled unit. They can handle high current loads but are not terrible tight in tolerance. A MOSFET regulator would likely help keep the voltage steady.

Dave

 

I added a regulator off a chinese scooter to my dirtbike, and then put a very small battery on it to help stabilize things.

I had a buddy that's smarter than me wire it up, so don't ask me a million questions about which color wire goes where. :secret:

 

Couple things.

U sure the R/R is not toast? Might be as simple as that. Also, a working R/R smooths the voltage out so no need for a capacitor.

LED's lose performance as voltage increases above their designed working load. If you bypassed the R/R then as you throttle up it might be giving it more (way more) than 12 volts thus causing the LEDs to under perform.