1984 r65, engine surging and battery dying

[craig@pmpress.org]

Hi fellas, just picked up a used and abused 1984 r65 and looking for some advice. It runs fine at idle and low speeds, but when I get up around 55 or so it will "surge" and the power will disappear even at full throttle. To compound this, after riding around for two or so hours on a fully charged battery, after shutting down it will not restart, battery is dead. On another bike with the same symptoms, a completely different F650 single, the culprit was a voltage regulator. Do you think it's the same here?

Possibly related the left signals do not work at all...nor the dashboard turn signal lights. Perhaps the diode board?



What do you think?

Thanks,
CO

[tvrla]

Welcome to the forum! And to the airheads!

And good for you for rehabilitating a needy one!

Several things could be causing the power loss:

clogged main jets or carb passages. Pull the main jets and I'll bet there's a load of junk up there around the atomizers. Also, the main jet orings could be shot.

fuel line filter could be plugged - this is probably the first thing to check. It's in the petcock.

floats set too low  - not enough fuel to draw from.

gas cap not venting - open it up when this happens to check.

Battery issue:

What does the charge indicator light do? Does it come on when the ignition is first turned on? When the engine is idling, is it on? Does it go out and stay out above 2K RPM?

If all yes, I'd guess a bad battery or connection.

The signal lights are a connection somewhere. That's going to require a wiring diagram - and I think there's one available on the site here somewhere. Maybe in the FAQs.

[montmil]

Welcome, Craig

My '81 displayed similar symptoms. Replacing the diaphragms in the carbs fixed that. Buy only genuine Bing diaphragms. Repops may be cheaper -at first- but you'll end up with the OEMs.

Evidently, your alternator is not charging the battery properly. The charging system doesn't really kick in until the revs pass 2K or so. This rev area can vary from bike to bike.

As to your charging problem, does the alternator charge light go off after revs come up? Is the bulb good? That little bulb is critical to proper function of the charging system.

To test the regulator, you can disconnect the regulator connection, make up a short jumper and connect it between the blue and black wires of the wiring harness, not to the regulator itself. start the engine and bring revs up to about 2K. If the alternator light goes out, the regulator is faulty.

I'd check the brushes in the alternator under the front engine cover. Remove the battery ground wire prior to removing the front engine cover. The brushes -there are two- are 15mm long when new. They should be replaced prior to reaching about half their length.

Check all wiring terminals for corrosion. Clean 'em up and add a light smear of dielectric grease.

Check these items and report back with what you find. Lots of help around here. We can help you get all charged up.

Monte

[Bob_Roller]

A hole or a tear in the carb diaphragm's may be part of your problem .

Kinda hard to say with a new to you bike, I think most comments would say go through the carbs and clean them up, spray carb cleaner through all of the orifices and passageways .

Your charging system sounds like it isn't working at all .

Like wirespokes has said, check your 'GEN' light on the tachometer and tell us what it is doing .

Normal operating charge light will come on when you turn the key to the "ON' position and stay on until around the 1500 rpm area and then stay off ubtil the engine comes back to idle .

[craig@pmpress.org]

Thanks fellas!

When I first got the bike it was leaking fuel out of the left carb (and mostly only running on the right cylinder), so I dropped the bowl, replaced the bowl gasket and cleaned it up. Replaced the gas, fuel filter, sprayed in carb cleaner and added some sea foam. I'll keep cleaning and look a bit closer at them both.

The Gen light seems to work normally (stays on til 1500 rpm or so) and go out. I'll test the VR as instructed.

Good news soon I hope!

[montmil]

The Gen light seems to work normally (stays on til 1500 rpm or so) and go out. I'll test the VR as instructed.

Do only a brief engine run test while the VR is out of the loop. A VOM attached at the  battery terminals will give you an idea of charging or not.

I replaced the 30-year old voltage regulator on my '81 with a solid-state unit from Rick Jones @ Motorrad Elektrik. Vast improvement in charging and battery performance.

http://www.motoelekt.com/charging.htm

Do a proper investigation of the entire charging circuit before throwing money and parts at the bike. Don't overlook the alternator brushes.

Monte

[Barry]

It runs fine at idle and low speeds, but when I get up around 55 or so it will "surge" and the power will disappear even at full throttle.

Surging on a steady throttle usually means you have a weak mixture for whatever reason. I'd be checking fuel flow, float levels, diaphragms and jets for blockage.  

While your in there check for a blocked or partially blocked atomiser above  the needle jet though that would cause a rich mixture and might go unoticed as far as running was concerned.

[tvrla]

If the alternator light functions normally, that tells me the alternator is functioning - at least well enough to charge the battery.

The regulator may be telling the system to put out less than optimum voltage, but it will still be charging. The light going out tells you that!

The light going out tells you the brushes are contacting properly and the diode board is functioning.

So the thing to determine now is how much is reaching the battery! Do that by hooking a volt meter to the battery terminals and note the charging voltage. It should be around 14V at 3500 RPM.

How old is the battery? That's one of the first items to suspect, though most riders don't

First places I'd look in your case -

battery terminals (are they bright and shiny or dull/corroded - disconnect them to look at the mating surfaces)

Ground connection at the transmission (same thing - disconnect and insure bright and shiny)

Large wire connecting to the right side of the diode board. This one is especially important! Make sure it's a very good connection!

Note - be very careful removing the front engine cover - it's easy to contact the diode board and blow it up. Most guys disconnect the battery first.

Oh - one more thing - your loss of power could be directly related to the low battery! Not enough oomph in the electrical system to provide a hot spark. As a matter of fact, that's my suspicion.

[craig@pmpress.org]

OK, back from the shed. I did this as Montmil suggested:

To test the regulator, you can disconnect the regulator connection, make up a short jumper and connect it between the blue and black wires of the wiring harness, not to the regulator itself. start the engine and bring revs up to about 2K. If the alternator light goes out, the regulator is faulty.

The light went out at around 2K (as it does when regulator is plugged in). Does everyone agree this would mean a new regulator?

Voltage back to the battery when the VR is plugged in never gets to 14, though on my last bike when the VR was out, it went higher, not lower (?)

Also patched a large tear in the exhaust (where the pipes are joined under the bike). Will get to messing with the carbs again in a bit after that cures. I went through the wiring and cleaned it all up a bit (it was rough) and now have all dash and turn signals working fine.

[tvrla]

What is the voltage at the battery at 3500 RPM?

The charge light should go out just above idle - say 1,000 - 1,200 RPM.

What was the voltage at the battery when you disconnected the VR and jumpered the connections?

I still don't have enough data to make any sort of diagnosis. It doesn't sound as if the VR is faulty if your test produced no change.

I'm wondering why it starts charging so late? What makes sense to me is the rotor is faulty with an open winding or two.

Just as a rule of thumb - the rotor is THE most common failure point. The VR and stator almost never fail. Brushes do wear out after a long time and can cause a few headaches, but usually it's the rotor.

[Bob_Roller]

How old is your battery ?

Is it a wet / flooded type, where you have to add distilled water to the cells ?

The voltage output test should be done on a fully charged battery .

[montmil]

So, we've got a charge lamp that lights up, a voltage regulator that's probably Ok, but a fault in the charging system remains... somewhere.

You can do a quick test on the rotor by turning on the ignition and bridging the two slip rings with a screwdriver blade or even a coin. When the rings are joined, the charge lamp should light up. This tells you the brushes are making contact with the slip rings but also would indicate a rotor with an open circuit.

There's a rotor removal tool that will save mucho grief when removing the rotor from the tapered crankshaft end.

Check it out. Report back to the class.

Monte

[tvrla]

The problem with static testing the rotor is they can test ok, yet fail in motion. The two best ways to diagnose is connect an oscilloscope to the output and determine if there are three phases or swap with a known good rotor.

The second most common failure is the diode board, and it can cause symptoms similar to yours.

In all, the common suspects are the battery, rotor and diode board.

[craig@pmpress.org]

Alright, I only had a few minutes down at the shed today. I charged the existing battery overnight, it's a UPG UT51913-22 Adventure Power Sealed AGM Battery and here's some numbers:

Battery voltage at rest: 12.5V
At idle (1250 rpm): 12.2
At 3500 rpm: 13.5

Withe VR unplugged: 12.2 at idle and ALSO 12.2 at 3500 rpm, no noticeable voltage change with the throttle on.  

What do you think?

[tvrla]

The idea was to also jumper the two leads when the VR was disconnected. With it out of the circuit, of course there will be no charging, and all you'll see is battery voltage. In this case, it's not 12.5 because .3Volt is being used for ignition, and was used for starting the bike.

But the 13.5V tells me your system is charging, just not as much as it could.

I recall reading somewhere that the amount of current flowing is more important than high voltage; 13 or 13.5 would be plenty sufficient as long as there's plenty of current. One of my bikes was like that, and as long as the connections caused no resistance to the flow, it worked fine.

Trying to determine low flow can be as much of a problem as finding an intermittent fault sometimes. First thing I'd do is check all the connections including grounds. Anything that doesn't look tip-top, make it so. After that, it's gotta be either the rotor or stator with a blown field. These are three phase systems and one phase can go out and still operate - but at a lower output.

If you could, do one more test for us - run it with the VR connection jumpered at 3500RPM and give us the Battery reading. If it's at 14 or 14.25, the alternator is good and the regulator is the culprit.

You see, what is happening when you jumper that connection is bypassing the regulator. The regulator TURNS OFF the alternator to keep the voltage down to the correct level. When you jumper those two leads, it's telling the system to GO FOR IT! There's no cops, no speed bumps - just pedal to the metal, go for it! So it'll put out every last millivolt it's got.

We want to know what it's capable of.