08 Venture MP bad stator or bad rectifier/regulator

[darren_t_johnson]

Hi,
I picked up an 08 Venture MP. I don't know anything about its history. But I took it out for the first time, and after a few hours of riding during the day and night, the next morning the battery was dead.

So I did some digging.
If I leave my two headlights disconnected, everything seems "normal". When running, my battery reads 14+. And it holds a charge. I put a new battery in just to be sure.
If I connect one head light, then when running, the light works, but the battery only reads approx 13.6.
If I connect both head lights, then when running, the light works, but the battery only reads approx 12.7, and I assume/expect that if I run it long enough it drains the battery as it is clearly not charging it.

So it sounds like either there isn't enough power being produced to support everything... or something is drawing more power or shorted.

Could this be signs of a bad stator or regulator/rectifier?

I tested the ohms of the stator as per the service manual and it is spot on (0.22 i think) for both of the readings it says to check. Is there more I can do to test the stator? Is it reasonable/practical to try and test each leg comming out of the stator?

Or, could it be a problem with the regulator/rectifier where it might not "use" all three input legs from the stator.. which would result in less watts being produced? It would still rectify to 14v, but less current. Is that even possible?

I've check relays and fuses. I've check for shorts from many many different places. I can't find anything so far.

any suggestions or answers to my questions above?

 

[kirkswim]

Do you know if the ground block update has been done?

 

[darren_t_johnson]

Yep. Its been done.

From the bulletin, it doesn't look like my model is supposed to be affected. Or maybe the bulletin was updated later to include my model. Regardless, I checked and the update has been done.

 

[darren_t_johnson]

i've also just been reading on how a regulator/rectifier with some blown diodes could also result in less DC power being produced. I've followed some test instructions for the diodes, and from one lead i read 445, 445, 445 and from the other lead I read 103, 103, 101 (i forget which reading was from the positive lead and which was from the negative lead of the rectifier). I don't know if that is bad or if all 6 readings should be in the 445'ish range. I have to read up on that a bit more to make sure i'm interpreting things correctly.

On the side, i'm starting to look in to what kind of cost and effort it would be for me to replace the stator... first time for everthing

 

[maim]

stator replacement will take 4-6 hrs with the oil change. mine took a week as i tore the stator cover gasket.

 

[darren_t_johnson]

Thanks maim

4-6 hours isn't too bad, i'll plan for 6+.
I know it will all depend on what I see when I get in there, but it is typically just the stator coil (ie 8GC-81410-00) that would need to be replace? Would the rotar or anything else typically need replacing?

Anyone have any thoughts on my voltage regulator readings? I would expect all 6 diodes to read the same. There was still an extra ground wire (i think) off the side of the regulator, so maybe that was throwing off the readings. I'll have to completely disconnect it and remeasure it to make sure its ok.

 

[maim]

new stator comes with a new crank position sensor and is bolted to the cover, no need to pull the flywheel unless you find teeth in the stator. might be a good time to pull the starter and get it rebuilt as you are right there. mine failed 5 months after i did my stator on the 09 phazer.

 

[74Nitro]

Do a running AC volt test of the stator.
It does sound like one phase is burnt out.

 

[Mooseman]

Check the ground wire plug near the battery. Although that plug would usually affect the ECU and other electronics, it's something to check.

The regulator is a little different to test as per this video:

If we follow that video, your regulator seems to be OK.

Did you check the stator for shorts to ground?

I have a spare regulator that I could check what kind of readings I get from and can be available to try swapping out as a test or replacement. Just have to find it in my pile of parts.

 

[darren_t_johnson]

Hi Mooseman, what do you mean by "check the ground wire plug near the battery"? You mean check for loose connections in that area causing a poor ground in one of the circuits?

From the test in that video, i agree, my regulator sounds OK. I don't think you need to go digging for old parts. Thanks though.

So I tested each stator wire to ground, and all three measured resistance... from what I understand, these should all read as an open right? So this means that at least one phase of the stator is shorted to ground (and apparently all three phases are wired together behind the coils? which explains why all three wires read resistance instead of just one?)

I did a running voltage test and measured all three phases (1-2, 1-3, 2-3). At 2500rpm, I read 42v, 42v, 35v. Given how the rectifier works, I would expect all three phases to produce nearly identical voltage. Does this mean the output of one phase is weak? And that would result in less wattage over all being output?

Given all this, is there anything else I should check? When I pull the stator, so I do any static tests on it? I guess re-confirm the short from one/all three wires to the body of the stator?

Side question: I read a lot on various articles/post about there being 3 phases; 1 phase for charging, 1 phase for lighting and 1 phase for accessories and everything else. Is that old information/design? From what i've learned about sleds and ATVs (at least ones built in the last 10-15 years) is that the 3 phase stator is run through a regulator rectifier and produces a single output of 12V that drives everything (lights, charging and everything else)ces a s

 

[74Nitro]

They should all be the same.
Looks like you have one low.
The phases are not designated to any particular part of the electrical systems on the machine.

 

[Mooseman]

So I tested each stator wire to ground, and all three measured resistance... from what I understand, these should all read as an open right? So this means that at least one phase of the stator is shorted to ground (and apparently all three phases are wired together behind the coils? which explains why all three wires read resistance instead of just one?)

That is correct. They should all read open so at least one of your coils is shorted to ground.

Given all this, is there anything else I should check? When I pull the stator, so I do any static tests on it? I guess re-confirm the short from one/all three wires to the body of the stator?

Once you pull it, you can re-confirm by checking each of the 3 phases to the metal body of the stator. Again should be open. It might be evident that it's burnt.

Side question: I read a lot on various articles/post about there being 3 phases; 1 phase for charging, 1 phase for lighting and 1 phase for accessories and everything else. Is that old information/design? From what i've learned about sleds and ATVs (at least ones built in the last 10-15 years) is that the 3 phase stator is run through a regulator rectifier and produces a single output of 12V that drives everything (lights, charging and everything else)ces a s

In the old days of 2 smokes, all 3 phases supplied power to lights and accessories as well as charging the battery if it had one. The spark plugs were supplied by another independent separate coil. With these 4 strokes, they are much more like cars where the stator's 3 phases power everything including ignition and there is only a small separate coil just to trigger the ignition coils, much like a crankshaft sensor.

A word of caution on a new stator, get only a Yamaha as I have read too many times where aftermarket ones, especially RMStator, fail again in short order.

 

[darren_t_johnson]

Thanks everyone!
Learned a lot so far.
I'll be picking away at this hopefully over the next few days.

Roger that on the Yamaha stator. I wasn't planning on cheaping out on that part. The savings are not very large, especially giving the savings of changing it out myself.

 

[74Nitro]

That is correct. They should all read open so at least one of your coils is shorted to ground.



Once you pull it, you can re-confirm by checking each of the 3 phases to the metal body of the stator. Again should be open. It might be evident that it's burnt.



In the old days of 2 smokes, all 3 phases supplied power to lights and accessories as well as charging the battery if it had one. The spark plugs were supplied by another independent separate coil. With these 4 strokes, they are much more like cars where the stator's 3 phases power everything including ignition and there is only a small separate coil just to trigger the ignition coils, much like a crankshaft sensor.

A word of caution on a new stator, get only a Yamaha as I have read too many times where aftermarket ones, especially RMStator, fail again in short order.

Hi Mooseman, with all due respect, your last statements are not correct. The two strokes that had a source coil to supply power to the ignition are not three phase.
A good example would be the 2000 SXR 700, compared to the 2001 SXR 700.

 

[Mooseman]

Hi Mooseman, with all due respect, your last statements are not correct. The two strokes that had a source coil to supply power to the ignition are not three phase.
A good example would be the 2000 SXR 700, compared to the 2001 SXR 700.

Isn't that what I said? 3 phase for power and a separate coil for the ignition? (alright, I didn't say it was a single phase)