5th gen Stator output

Hi VFR guys and gals, 

I'm having charging problems. I think my stator is the problem. It is 12 years of age and has at least 40k miles on it. I know that engine heat causes stator failures. Per the factory manual, there is continuity across all 3 poles. Each pole produces about 10V which does seem low. The last time I had to replace the stator, 2, but not all 3, poles could power a 60 incandescent bulb. Now, none of the poles can power a 40W incandescent bulb. Part of the reason I suspect the stator is I have a MOSFET R&R, which have a rock solid reputation.  My connectors are clean, no burning or corrosion. I removed the OEM connectors a long time ago. 

10V when? Did you follow the manual for the test for ohms and VAC...and continuity to ground? 

10V when connected to the R&R. I browsed here a little and it seems the incandescent light bulb test is correct only when disconnected from the R&R, and that voltage should be about 65 V. When I disconnect the R&R, my volts across each pole range from 28 to 35, which is low, but I didn’t try the light  bulb test.

Forgot to mention that yes, I have less than 1 ohm across each of the 3 stator poles.

The R&R is a Roadster cycle Super Mosfet kit. There is battery voltage across the R&R black connector. The continuity test on page 16-12 of the manual doesn’t seem appropriate because my MOSFET R&R has 2 pins, not 3 pins.

Attached pictures for reference.

You're not mentioning the most important test and the most common mode of failure, it's the phase to Ground test. With the 3 phase stator lead unplugged from the R/R probe each phase wire with the other meter leaded grounded, you should have NO continuity to Ground - Open circuit, no shorts to Ground, meter set to high resistance range. A low ohms reading will mean your Stator is toast.

It's hard to determine a Phase to Phase short with a multimeter because the coils are of such low ohms value 0.1 to 1ohm. However a Phase to Phase short wil show up as low AC output voltage.

With the main R/R Positive output wire (refer your top photo), is that going through a normal 30amp Fuse OR is it an Auto Reset Circuit Breaker before going to the Battery Positive? If its the latter, replace it ASAP with a 30amp Fuse!

Also the 3 wire R/R Plug you're holding. Do the spade sockets look burnt or splayed? Are they making good tight contact with the R/R side? Vitally important that they make good tight contact and perhaps a little OxGard wouldn't go astray on the contacts.

"The continuity test on page 16-12 of the manual doesn’t seem appropriate because my MOSFET R&R has 2 pins, not 3 pins."

The 3 pins the Service Manual page 16-12 table,  is referring to the resistance value of the three stator wires coming into the R/R = "Charging Coil Line"!

Sorry to say it, but that wiring looks a mess! could do with a good tidy up, however YMMV.

Good Luck.

All phases are open circuit to ground. Meter set to 2 million ohms. The R/R contacts are not burnt nor splayed. 

R/R output wire: I think this is a fuse, not a breaker, but I really don’t know. It came with Roadster Cycle Super MOSFET kit.

Yes, wiring is messy because when the big undocumented ground connector melted a few years back, I soldered all the ground wires together and I found it easier to cut away the outside sheath.  

Last week on a ride I had to push start it after a fuel stop, but that was partly because of corrosion and melting at the main fuse connector and the downstream single wire connector. Main fuse and its connector have been replaced and Ox Guarded, and the single wire connector has been replaced with solder and heat shrink. Today on a ride, my voltmeter which is taped to top triple tree briefly reported < 12 V with rpm in the 4k to 5k range. I pulled over ASAP, disconnected the headlamps, and rode home with no issues, and the voltmeter typically displaying >14 V.

Maybe I have a stator that is close to failing, and I simply need to ride it some more, while keeping a close eye on the voltmeter, and not take any long trips.

[image: 2024-10-12_21-04-26.png]

[image: 2024-10-12_21-04-54.png]

..... :ph34r: .....

If it doesn't have a replaceable fuse then it's an auto reset breaker. Strongly suggest replacing it with a normal weather resistant 30amp fuse. Something like attached photo available at any good auto spares shop.

Is the R/R a genuine Shindengen FA020AA?

Ok, Thanks, I will get the fuse. R/R is Shindengen FH020AA.

And really...follow the manual. Stator has multiple check, some at/around specific RPM. (Why I asked)

@vfr800_red...... Dude, you even have a multimeter?

If you used the breaker shipped by Roadster with your 020, it's almost certainly the auto-reset type.  IDK why he uses those.  IMHO they're crap.  I ditched mine for a 30A replaceable maxi fuse. 

Also, if you do replace the stator, swapping to a 6th gen stator and flywheel is a nice upgrade.  Prior to doing mine, at idle when the cooling fan kicked on my VM was reading below battery voltage - and I have LED headlights, so my base current draw is very low.  My stator is (was) low mile and checked out fine.  After the swap I get around 13.5 with the fan running and 14.5 (as before) going down the road.

 A couple of things to note if doing this: 

1.  Although the 5th and 6th gen blocks share much in common, stator covers are not one of them.  You'll need to retain your 5th gen cover. 

2.  The 6th gen stator will bolt right in directly to the 5th gen cover, however the stators are NOT the same thickness.  IIRC (it's been a year now) the 6th gen stator is slightly thinner, thus the 5th gen bolts will bottom out in the blind hole before drawing the 6th gen stator down tight.  DO NOT keep tightening the bolts b/c the stator remains a bit loose lest the threads strip, ruining the cover.  Get some slightly shorter socket cap bolts and torque them to spec.  Do some measuring to satisfy yourself that you've accounted for any differences. 

3.  To get the 5th gen flywheel off, best bet is to use an impact gun.  Rent or borrow if necessary.  Holding that little beastie in place is a real PITA, even if you do have a strap wrench or similar to place around it.  It might be doable with 2 sets of hands, dunno about that - I did mine solo.  Impact gun makes quick work of it.  I kept it on the lowest setting that would remove it to minimize the shock load to the crank. 

4.  If the flywheel is a no-go coming off the crank snout, go to an auto parts store and pick up a 20mm X 1.5 oil drain plug.  It should thread easily by hand in to the center of the flywheel - do not force it.  If not, check the plug threads or possibly you have the wrong size.  Once it bottoms, use a wrench to tighten, then the flywheel should pop right off.  The plug should cost $2 to $3, not the $20+ on Amazon or $$$$$ from Honda. 

5.  The 6th gen flywheel has two flats on the hub that I could fit a large adjustable wrench on (which the 5th gen flywheel lacks).   That made applying the 76 foot pounds to the bolt a breeze.  So for me this became a one way trip - once the 5th gen flywheel was off I was committed to the 6th gen, as I had no way or re-torquing the 5th gen flywheel.  I do not recommend re-torquing the flywheel with an impact gun.  That's one of the critical fasteners that needs to be correct - close may not be good enough. 

6.  The "V" shaped grommet on the 6th gen stator wiring was larger than the V groove in the cover - it required some trimming.  Since I had the new stator re-wound, IDK if that was because they used something different than OEM or if there's a difference in the two covers which need a different size grommet.  Regardless, I did some trimming.  My trimming work wasn't perfect, so I used a skim coat of silicone and have had no leaks in the 1,000 miles I've been running it. 

7.  If your gasket breaks apart when removing the stator cover, be sure to use only plastic scrapers.  Use of a steel scraper will surely scratch the aluminum and you'll have leaks.  After 25 years, removing the gasket was difficult - the best thing I could find to soften it was acetone, which actually did a pretty decent job.  From what I hear, the EPA has pretty much neutered most gasket removers we have today.  Gaskets are NLA from Honda (as are 5th gen stators), but there are sources on ebay that will do fine.  I applied a thin film of grease to the gasket to make future removal easier. 

When doing this swap, I followed the lead of others that have also done it.  I was skeptical - I did a lot of measuring to see if there were any clearance issues with the 6th gen flywheel. I used modeling clay to check for clearances whilst assembled and applying bluing to various places that looked like could be problematic.  Everything came up ok.  Once assembled, I turned the engine over without starting it, the took it back apart to see if there were any signs of rubbing, scraping or interference.  All looked good.  Be sure you are satisfied that all is good before the 1st startup. 

Overall I'm very happy with it - the output is definitely improved and so far it's been a seamless swap.   YMMV

Good info Cogs!  :fing02:

Hi,

It definitely sounds like your stator is on its way out, especially with the low voltage across the poles and the fact that none can power the 40W bulb. Given its age and mileage, plus the heat wear over time, it’s likely the culprit. The MOSFET R&R is reliable, so if the connections are clean and you’ve ruled out other issues, replacing the stator seems like the next step.

Thanks

Test the Stator! With a multimeter! 

1. Check each leg... AB, AC, BC...... Resistance 1.0 ohms or less..

2. Check each leg to ground... no continuity, nada, nothing... 

3. Bike running.... AB,AC, BC....  at AC volts idle and 5000 rpm.... idle...around 20 volts AC, 5000rpm, 50+ volts AC 

 -----IF things still look good, then test HOT. 

And very first thing.... a good battery is a must! 

More than that...1 & 2 are engine off. 3 is with connector disconnected. 

1 hour ago, bmart

More than that...1 & 2 are engine off. 3 is with connector disconnected. 

Oops thanks....all 3 are connector disconnected....

Update:

Yes, I’ve done all the above tests, and the fault was low AC voltage output so as Grumm mentioned this would be 2 phases shorted together. This failure is not documented in the manual, and my 2nd stator which had this failure. Each lasted about 40k miles, so not bad.

I was confused a little by the manual because page 16-12 describes checking that each stator phase is not shorted to ground as an R/R test. Also was a little confused because the OEM R/R has a 4 pin output, but the MOSFET R/R has a 2 pin output. It has been 12 years since I’ve seen the OEM R/R, but I understand now they just doubled up the wires.

5th gen OEM stators are no longer available, so I purchased an inexpensive aftermarket stator on Ebay, Caltric, which includes a new gasket. I know sometimes aftermarket parts are lower quality than OEM, but the seller has a 97.6% positive rating.  Put it on the bike last night and have 60VAC @ 5k rpm across all 3 phases. Didn’t have any problems removing the old gasket. I should solder the wires to the MOSFET R/R later today, finish assembly on the remainder of the bike, and if the weather cooperates, be riding this weekend. It is late in the season where I live.

Great information about the 6th gen stator and flywheel, I assume that OEM of those are still available. Maybe I’ll go ahead and purchase these as I’d like to keep the bike going for many more years. Here’s a trick could help remove the flywheel nut: remove a spark plug then place rope in that cylinder. That worked well when I torqued a crank pulley on a Toyota Camry.

And I replaced the auto reset breaker with a 30A fuse holder. Nice to learn that, always wondered what that was.

I don’t come here much, but this discussion group is an invaluable resource to keep these aging bikes going. I attempted to give a donation, but when I click the pay now button, it says “This organization can't accept donations right now “, perhaps because the total donations have exceeded the total goal. If so, I’ll set a reminder to make an early 2025 donation.

Caltric makes mostly garbage. Buy a genuine brand or just have your OEM rewound. Many shops still do this. You can always rely on Rick's. 

10 hours ago, bmart

Caltric makes mostly garbage. Buy a genuine brand or just have your OEM rewound. Many shops still do this. You can always rely on Rick's. 

I completely agree with you!  My oem still going strong (for now) @ 61k.  I have a Ricks here w gasket ready to go. And when it happens, I'll send oem off for repair.  

vfr800_red, 10/17/2024 at 6:49 AM

Update:

Yes, I’ve done all the above tests, and the fault was low AC voltage output so as Grumm mentioned this would be 2 phases shorted together. This failure is not documented in the manual, and my 2nd stator which had this failure. Each lasted about 40k miles, so not bad.

I was confused a little by the manual because page 16-12 describes checking that each stator phase is not shorted to ground as an R/R test. Also was a little confused because the OEM R/R has a 4 pin output, but the MOSFET R/R has a 2 pin output. It has been 12 years since I’ve seen the OEM R/R, but I understand now they just doubled up the wires.

5th gen OEM stators are no longer available, so I purchased an inexpensive aftermarket stator on Ebay, Caltric, which includes a new gasket. I know sometimes aftermarket parts are lower quality than OEM, but the seller has a 97.6% positive rating.  Put it on the bike last night and have 60VAC @ 5k rpm across all 3 phases. Didn’t have any problems removing the old gasket. I should solder the wires to the MOSFET R/R later today, finish assembly on the remainder of the bike, and if the weather cooperates, be riding this weekend. It is late in the season where I live.

Great information about the 6th gen stator and flywheel, I assume that OEM of those are still available. Maybe I’ll go ahead and purchase these as I’d like to keep the bike going for many more years. Here’s a trick could help remove the flywheel nut: remove a spark plug then place rope in that cylinder. That worked well when I torqued a crank pulley on a Toyota Camry.

And I replaced the auto reset breaker with a 30A fuse holder. Nice to learn that, always wondered what that was.

I don’t come here much, but this discussion group is an invaluable resource to keep these aging bikes going. I attempted to give a donation, but when I click the pay now button, it says “This organization can't accept donations right now “, perhaps because the total donations have exceeded the total goal. If so, I’ll set a reminder to make an early 2025 donation.

I would recommend that you hang on to your 5th gen OEM stator.  If the Chinese stator disappoints, you can always have the OEM stator re-wound by Custom Rewind in Birmingham, AL.    A number of members here have used them and I've never seen one complaint.  I've used them twice - they've done a great job for me.  The last IIRC was $135, you pay shipping to them, return is included in the cost.  Call 1st to get up to date pricing.  You may have to leave a message and he'll call you back.  

1 hour ago, Cogswell

I would recommend that you hang on to your 5th gen OEM stator.  If the Chinese stator disappoints, you can always have the OEM stator re-wound by Custom Rewind in Birmingham, AL.    A number of members here have used them and I've never seen one complaint.  I've used them twice - they've done a great job for me.  The last IIRC was $135, you pay shipping to them, return is included in the cost.  Call 1st to get up to date pricing.  You may have to leave a message and he'll call you back.  

[image: Custom Rewind .png]

I am running a CR rewind stator. I asked for extended leads so I could add the Furakawa connector direct.

2 years worth and it's rock solid, no issues.

I have another one on the bench I want to get done as a backup, although at my current annual mileage I'll never need it.