Yamaha R6 Forum: YZF-R6 Forums banner

1 - 11 of 11 Posts

·
Registered
Joined
·
40 Posts
Discussion Starter #1
Gents,

I've pulled the 3-pin stator connector on my 2006 R6 and am measuring the voltage across each of the phases at idle. I'm expecting something greater than 10VAC on each phase, but what I am getting is this: 2 phases show just a tad over 1VAC and the other phase nothing.

Checking with the engine off, there is NO continuity between any of the three stator wires and ground on the bike; there is continuity between the three wires themselves (the SM says resistance should be 0.12 - 0.18 ohm, but I cannot measure resistance that low with my multimeter.)

With the engine off, I also ran a leak test, disconnecting the negative lead from the battery and putting the multimeter as an ammeter between the lead and the negative terminal on the battery. There is current flow, but very small (< 1mA). Also, the battery is not dropping in voltage after sitting for a couple days, so I think that's all good.

That leaves us with the stator and the regulator/rectififer. My understanding of the failure modes of the stator is that it would short to ground, or short internally between the phases. The first case is not happening, but the second? Asymetric (and very low) voltage output seems wrong, but I am not finding any reference to this particular failure mode.

History: I got the Rossi code (46) whist riding. The bike eventually just stopped running, and would not start up. Got it home and found the battery discharged. Optimate brought the battery back up (as I said, it's holding its charge nicely now), but after cranking, the voltage is just over 12VDC, not charging. Trying to figure out if it's the rectifier/regulator, stator, or both, or something else going on with the bike.

I really want to be sure the stator is faulty before ordering a new one. They're dear (~€450). And if I replace the stator, I'll probably replace the rectifier too just in case it has also gone. Don't want it wrecking a new stator.

Cheers
 

·
Registered
Joined
·
1,949 Posts
I've just gone through dealing with this as well. Assuming your voltage readings are correct I think that's more than enough evidence to start with the stator. I'd pull the stator cover off and look. For me, it was super obvious as several of the coils were completely burned up. Just buy new gaskets for that case cover. They almost always get fouled up pulling the cover off or damaged by accidentally letting go of the cover before it's lined up. I don't reuse gaskets but I definitely do not reuse that gasket because of those reasons.
 

·
Registered
Joined
·
40 Posts
Discussion Starter #3
I've just gone through dealing with this as well. Assuming your voltage readings are correct I think that's more than enough evidence to start with the stator. I'd pull the stator cover off and look. For me, it was super obvious as several of the coils were completely burned up. Just buy new gaskets for that case cover. They almost always get fouled up pulling the cover off or damaged by accidentally letting go of the cover before it's lined up. I don't reuse gaskets but I definitely do not reuse that gasket because of those reasons.
Thanks for the advice. Good to hear that stator failure is not entirely an uncommon event.

Before I pull the cover, I want to make sure I have a plan to get everything back together in a good way to minimize damaging either the (new) stator or the new gasket.

Do you have any tips for dealing with the magnetic pull when putting the cover back on?
 

·
Registered
Joined
·
1,949 Posts
Not really. There are little tabs around the outside of the cover. I just hold on to those and just slowly move the cover into place. You just want it to go on straight so just try and hold it against the magnetism. It's really not that bad. It's only when you either don't have a good grip on it or forget about the magnetism and it snaps on crooked and bends the gasket.

I like to take a super small dap of gasket maker and place a few tiny smears at certain points around sealing edge on the engine to hold it in place. Then place the gasket on the engine side and put the cover on.

The bolts for the stator are on tight and have thread locker on them. I had no issues getting mine off, but others have mentioned getting those bolts loose was a pain, so just fyi.

When tightening down the cover work around the cover in a star pattern.

I assume you have access to the service manual as well?
 

·
Registered
Joined
·
40 Posts
Discussion Starter #5
Not really. There are little tabs around the outside of the cover. I just hold on to those and just slowly move the cover into place. You just want it to go on straight so just try and hold it against the magnetism. It's really not that bad. It's only when you either don't have a good grip on it or forget about the magnetism and it snaps on crooked and bends the gasket.

I like to take a super small dap of gasket maker and place a few tiny smears at certain points around sealing edge on the engine to hold it in place. Then place the gasket on the engine side and put the cover on.

The bolts for the stator are on tight and have thread locker on them. I had no issues getting mine off, but others have mentioned getting those bolts loose was a pain, so just fyi.

When tightening down the cover work around the cover in a star pattern.

I assume you have access to the service manual as well?
Super suggestions, thanks! I had not thought about a dab of gasket maker on the gasket to hold it in place on the engine side, that will help immensely.

I have a torx bit socket set that I was planning to use with a breaker bar to go at the stator bolts. For breaking the Loctite bonds, I read that tightening the bolt a bit first before backing it out helps break the bond. Will try that. Have the service manual, it's a little scant with info on this, but does have the torque specs. Haynes manual has a few pictures and some info as well. The torque on those bolts is really minimal -- 10Nm -- and the cover bolts are only a little more, 12Nm if I recall. 10Nm is right at the bottom end of my torque wrench. I'm planning to loctite the stator bolts and tighten everything back up to spec.
 

·
Registered
Joined
·
5 Posts
I would look at the coils first before trying to replace the stator. I just went through having one of the two coils failing on my Yamaha YZF600. The coil would heat up and fail, which resulted in the motorcycle stalling, due to carb flooding. No spark, but accelerator open flooded the carbs. Waiting 45 minutes from the coil to cool down, got to be very annoying. I had both coils replace at the shop and the bike runs as smooth as the day I bought it. By the way, you can find after-market coils for far less the the OEM ones.
 

·
Registered
Joined
·
40 Posts
Discussion Starter #8
Popped off the cover to take a look...
IMG_20200820_122912.jpg


Yamaha parts is closed until next month (holidays). So I get to wait. The regulator/rectifier looks OK; its connector and pins are spotless (no corrosion or anything burnt), but I'm thinking I'll replace it as well, so they get replaced as a pair, just in case one is inducing a failure in the other.

375535
 

·
Registered
Joined
·
1,949 Posts
Yep that stator is toast. Looks exactly like mine did. The rest of the windings are so much cleaner than mine, haha. I had an extra stator which was slightly used and the windings were not that light brown and now I am nervous the stator I put in is on it's way out too. The windings were much darker than that and of every other pic I have seen of stators.

When you get your new stator would you mind taking AC voltage readings just so I can compare new to used? I might suck it up and do the same thing. Just replace with new, just tough to swallow the price pill.

I am not sure if Rick Motorsports ships to your country but worth a check. You can get quality stators and R/R for half the price.
 

·
Registered
Joined
·
40 Posts
Discussion Starter #10
When you get your new stator would you mind taking AC voltage readings just so I can compare new to used? I might suck it up and do the same thing. Just replace with new, just tough to swallow the price pill.
No problem at all. I can take measurements at idle and say 5000rpm.

I am not sure if Rick Motorsports ships to your country but worth a check. You can get quality stators and R/R for half the price.
I e-mailed them and found out they distribute through Parts Europe. There is one dealer in my area. I am putting together the Rick Motorsports parts list for stator and regulator, and will go over there today to see what they can do for me.
 

·
Registered
Joined
·
40 Posts
Discussion Starter #11
@Flyers28 At last, I have a working bike again... Renewed both stator and RR. No issues or surprises during installation.

As promised, the open-circuit voltage readings from the new stator are (on all three phases):
idle: 15VAC​
5k rpm: 48VAC​

Voltages at the battery are:

idle: 13.8VDC​
5k rpm: 14.0VDC​

Just took 100km test ride. No oil leaks, no issues during ride. Battery voltage after switching the engine off was 12.9VDC. RR heat sink was only slightly warm after the ride; I could hold onto it without discomfort.

The charging system seems to be operating normally at this point. Thank you for your advice and encouragement!
 
1 - 11 of 11 Posts
Top