Ducati Monster Forum

Usually I will turn the key on, open the throttle a few times and hit the starter. Most times it takes a couple of tries with the motor turning over to catch and fire up. I attributed that to the FCR's and 15/50 oil. Once warm there is no issue.

Lately the starter seems weak. Or maybe the coils?
I try the same sequence as above but now the engine doesnt want to turn over. It tries, and the pulleys move a tad but it feels and looks like when you try to start a high compression motor without a suitable starter.
I have resorted to bump starting when it cant do it electrically.

At the end of my track day I ran out of fuel so my brother gave me some 93 with octane booster (only thing he had) and the starting problem seems worse since that addition. Could be my imagination.

Battery is good. No issues there.
I plan on removing the 93+ octane gas and put in fresh 87.
How do I test the health of my starter and coils?

Another weird thing that happened yesterday is that when it finally started electrically the starter would not turn off. Just kept turning over after the motor was running. Killed the motor by having to turn the key off then on, then off again. Kill switch did not respond and the contacts were cleaned just hours prior. (this weird starter-not-turning-off thing has not appeared since)

Check your rectifier ground, and especially the three wires running from the alternator to the rectifier.

My rectifier was going bad, and made those three wires get hot enough that they melted together and I was having similar symptoms as you. Replaced rectifier and soldered in new wires and I've been golden ever since.

Will do. thanks chris.

Cant remember, does the R/R have a ground wire or must it have a hard ground (such as the frame)?

Yeah it's a hard ground, so check for rust/oxidation between the bolts/itself/frame-tabs.

Never knew that. My dumbass has it mounted under my lower triple tree. But I would think that an ungrounded electrical component would have an immediate result/symptom, not a gradual one. No?

Correct... but they're usually mounted right behind the lower triple tree, on a little tab on the frame itself. What year is your bike?

99 750.
Well I will move it to a spot on the frame, change the gas, clean the plugs and see what happens

You know your battery is good how?  Your symptom is that of a bad battery, high resistance in a connection or a charging system problem.  Weak coils do not affect cranking speed.  Start with fully charging the battery and the load test.  Replace if needed, then check the charging system.  You want to see 13.5 -14.5 volts across the battery at about 3K RPM.  Above or below?  http://www.electrosport.com/technical-resources/diagnosis-center/fault-finding-guide (http://www.electrosport.com/technical-resources/diagnosis-center/fault-finding-guide)   Definitely make sure your grounds and battery connections are good.  Then start looking for voltage drop.

Starter Circuit Voltage Drop (http://www.youtube.com/watch?v=ry68G0C2Fyc#)

Yes, it's a truck. but the same applies.

Oh, the bike continuing to crank was a sticking solenoid, usually caused by the above.  Low voltage causes the contacts inside the solenoid to stick.  Might, might not happen again.  You can buy a replacement from  http://www.ca-cycleworks.com (http://www.ca-cycleworks.com)

I was just reading about start loops and solenoids. Nice. I checked with a multi meter, but not running. Never occurred to me to check it that way. Will do so tomorrow.
With luck my r/r or solenoid isn't ruined.
You think that not having it grounded properly creates more draw from the battery? I just can't think of what might be causing the drop in charge if that is indeed my problem.
More will be sorted tomorrow.
Thanks Howie

Moved the R/R to a spot on the frame. Did not experience the looping start.
Load tested the battery and it read 14.7 at about 3000rpms.
Start is still difficult in that it still takes a few tries to get it to even turn over.
Possible culprits? Solenoid? Starter motor?

Are those three wires from the alternator to rectifier all okay?

Someone correct me if that's not a possible culprit please. I just know that I had mine melt together, so now I suspect that when I hear of people's electrical problems.

Load testing means charging the battery and taking it to a shop that has the ability to load test it.  The shop will then apply a load to it.  The proper test is 3X the am hour rating of the battery or 1/2 the cold cranking amps for 15 seconds.  If the battery drops below 9.6 volts it is bad.  Most motorcycle shops use something like this

http://www.harborfreight.com/amp-6-volt12-volt-battery-load-tester-69888.html (http://www.harborfreight.com/amp-6-volt12-volt-battery-load-tester-69888.html)

You can also substitute or jump with a known good battery.  Going further without testing the battery is pointless.  Then, after confirming the battery is good you continue testing.  Your charging rate is a little high, but make sure the battery is good first then re test.  You moved the regulator to where?  On your bike the regulator is in an ideal position, open and in the airstream.  Almost 66k miles and 12 years on my OEM regulator.  '02 and newer are more problematic as they are under the seat.  No place for the heat to go.  Just make sure it is grounded.  Then move on to voltage drop tests as in the video.  A bad solenoid will show up in the voltage drop test as excessive voltage drop. If all that checks out then we can talk about starter testing.  Cheap stuff first. Yes, a bad ground will cause this and might cause your ignition modules to suffer an early death.

Voltage drop is the amount of voltage consumed by a load (bulb, motor, relay, connection, conductor, etc.  Too much voltage drop is bad.  Ohm's law says
E (voltage) = I (amperage) / R (resistance).  Voltage goes down amperage goes up, viola, things don't work.  Also, excessive resistance in a switch,wire or connection causes heat.  Heat causes fire, like the famous cooked stator to regulator connection common on Ducatis and other motorcycles.  The video shows voltage drop testing rather well.  Not clear to you?  Just google voltage drop test.  In a classroom I would draw it on the board, then take you to a live vehicle.  Much easier that way.  I prefer testing before cleaning so you know you found the problem.  You would be surprised how many times an expensive component like a starter is replaced unnecessarily because of poor diagnosis.  When changing the starter the mechanic accidentally repairs the real problem, the bad connection.  No one knows, life goes on.  

If the culprit is the connection at the starter, disassemble with care.  It is easy to break that stud inside the $tarter.


I think Memper's bike may be old enough to have only two (single phase alternator)  Yes, common problem spot.  Cheesy connector barely able to carry the current, open to the environment.  Some people eliminate it, IMO the problem there is future diagnosis.  Some people replace it with a quality weatherpack connector, some, like me, just inspect, clean and pack with dielectric grease.

I get it. Thanks.
So I guess its off to a cycle shop (or auto parts store perhaps??) to have the battery load tested.
But if my battery was gonna show weakness with a load tester, wouldnt it also show weakness with a multimeter?

As far as the connection goes, about 2 or 3 months ago I deleted the connector and soldered my wires. However, for the sake of aesthetics I added about 6" of wire so I could stealthily run them behind some of the trellis. Added resistance here? Not sure how much...

I relocated the RR to the tabs that are behind the lower tree.

The bike is a '99 750. The RR has more than two wires...4 if I remember right. 

The multimeter will show you state of charge, not capacity.  If the 6" of wire is the same gauge all should be good.Where was the regulator?  Sounds like you moved it back to it's original location.  Either 2 or 3 yellow wires from the stator, we aren't counting the other wires right now.

My bike's a year older than his and I have three wires, or is it different from his 750 to my 900?

Nope.  I didn't remember the year of Memper's bike or when Monsters went to 3 phase.  Memper's would have 3 wires.

I just looked and total wires coming out of the RR are: 3 yellow, 2 green, 2 red.

This is besides the point though.

I will get the battery checked. If the battery IS messed up I will be surprised. Its an Odyssey which in my experience with other bikes are bulletproof batteries. if it does happen to be toast it gives me an excuse to buy a LifePo4.

...and if your bike is overcharging it will most likely cook another new battery. ;)

Whats the possible causes for over charging?
I think I found the looping starter issue...I had the start button housing too tight on the bars. I knew all three buttons felt funny.
Still gonna get the battery checked for good measure.
Probably doesn't help that my plugs are soaked with 93+ fuel...

Regulator/Rectifier

Yes it will.  I don't know if this holds true for our waste type regulators, but on a regulator that controls field, like those on cars and Gold Wings a battery that lacks internal resistance can cause overcharging, rare, but it happens.  Maybe Suzyj can comment.  Either way, the battery should be tested.

My original R/R failed and was overcharging.

I had, and still do, a standard lead acid battery, so it was OK as long as I kept the level up.

Doesn't work so well on a sealed unit.

Welp, it seems like I have my hands full of testing when I get back from vacation.

So I understand the dominos, could the scenario have gone down like this?:
-ungrounded RR gets toasted.
-resulting in poor battery performance
-resulting in sticking solenoid function

Yes, a likely scenario.

Ah, and back to the meter understanding, my meter could show 14 volts but that could very well be 14 volts but only at 50% capacity, right?

The voltage reading on the battery with the engine off is like checking to see how full the glass is.

Load testing a battery tells you whether it's a shot glass or a pint glass.

The 14.7v while charging is an indicator of a stuffed battery.

A good battery holds close to the nominal 13.8 both while charging and while starting. A bad one goes way over while charging and way under when loaded.

An excellent analogy! [drink]

Thank you, I wasn't sure if this applied to our waste type regulators since I really don't know what is in them besides transistors and diodes.  On cars, back in the old days, when regulators were adjustable we used to use a .25 ohm resistor to simulate a good battery.  Solid state regulators put an end to that.

Why is it so hard to convince people the first step to charging/starting diagnosis is to confirm the battery is good?

The stator, rectifier/regulator and battery are designed as a system. The stator needs the rectifier load to keep things from arcing. The rectifier/regulator needs a battery to keep the output voltage within spec. If the battery is stuffed, it doesn't take current from the rectifier/regulator, which then has to shunt that current itself. In an ideal world that would be fine, and the regulator would hold the voltage within spec itself. But these things are built to a price, and without a load the voltage rises significantly.

You're right that the rectifier/regulator may be stuffed also. If it spends too much time shunting all that excess current, those components will fail, and it will no longer be able to regulate properly. Conversely it can fail all by itself and damage the battery in turn.

So for the OP: replace the battery, then carefully monitor the voltage with the bike off, with it running at idle, and with it running at a few thousand rpm. If it goes over about 14.2v with a fresh battery, your rectifier/regulator is damaged, and will cook your new battery if you leave it on.

There's a scenario that I seem to read way too often. Someone has trouble starting their bike. It's a damaged rectifier/regulator, which in turn has damaged the battery. They replace the battery blindly, and the bike works, so they think they've fixed it. A few weeks later, the bike won't start, so they replace the rectifier/regulator. They ignore advice that their battery might be stuffed, because its only a few weeks old. They stagger on for months with their starting problems, not really understanding how the different parts can actually damage one another.

Thanks folks. We'll see in a couple weeks...off for vacation!

Well I got my new MOSFET R/R today and my LifePO4 should be arriving tomorrow. Hopefully I can do the install next week.

Just to update, I hard wired the MOSFET rr (no likey connectors) and installed an Alien Motion 8 cell LifePo. Fires up hard and quick.

Great!