View Full Version : Stator problems

12-03-2011, 12:32 PM
I recently read several threads in this forum on stator failures. This is of interest to me because my '08 Tuono R has been diagnosed as having a faulty stator assembly.
To begin, the T ran flawlessly for about 8000 mi. I had the prescribed services, and later added Leo Vince silencers and remappping. I recently experienced an infrequent miss/hesitation, seemed usually at lower rpm's around 2K. I would turn the bike off. It would restart and ride fine. Then the same scenario would pop up. I trucked it to the local shop (Moto Forza) who had serviced the bike. They found the stator assembly to be faulty which caused the battery to be faulty, and since as I understand the system the ignition is integral with the EFI, the supply of fuel to the injectors was the problem causing the missing or cutting out. Since I am somewhat skeptical of advice on subjects I know little about, especially since the fix will cost about $900, I am seeking information and advice from those who've had similar experiences.
Any advice would be greatly appreciated.

12-03-2011, 07:03 PM
I would turn the bike off. It would restart and ride fine. In that case, I doubt there's anything wrong with either your stator or your battery. If you don't know how to do it yourself, get a friend to check your key-off battery voltage after the bike has sat unused for at least an hour. If it's 12.6 volts or better, the battery is in good condition and fully charged (no stator issues). But just to be sure, start the bike, hold the revs around 2500, and see if it's getting the battery up to 14 volts or better.

Stu O

12-03-2011, 07:41 PM
Cheaper alternative is ricks stator. I do believe af1 sells them about 140$ if i remember right

12-04-2011, 10:08 AM
Wouldn't this be covered under warranty? I thought Aprilia admitted fault in the 2nd generation design of the stator/rotor, and came up with a new lower-watt stator around 2008. Or am I dreaming?

12-04-2011, 11:49 AM
Thank you for the advice. The shop did test the battery as you suggested STU O and it was not charging properly and the shop was surprised it would start with such a low output. The mechanic took it out for a test ride. It ran fine until he returned to the shop and the motor missed and stumbled at lower RPM. Subsequent system check revealed the batteryy at low output presuming the stator system faulty.
As to the aftermarket part, from what I've read in this forum one's better off with OEM parts, though more expensive. Diablo, I don't know about the warranty thing. If anyone else out there does please let me know.
My concern is based upon what I've read here. Several posts about stator failures and not just once. Some are on their third stator assembly! Is there an inherent design flaw? If so, is there a reasonable fix other than replacing the unit when it fails? Pretty damn expensive!

12-04-2011, 12:29 PM
The best way to determine if there is a stator problem is to measure the stator output at 4,000 rpm.There are three stator leads and you need to connect an AC voltmeter to two leads at a time and measure the voltage. Each pair of wires should measure around 60 volts. Compare the three readings - any very low voltage means that the windings on that stator leg are fried (insulation burnt and wire grounded out).

2nd generation RSVRs (2004-2009) are the ones that have stator issues. When the bike was designed, they used a higher output alternator. My understading is they reverted to a lower output alternator in 2007-2008, that should not have the problem. If you have a problem with your stator, I would try to have Aprilia fix it under warranty with the latest low-output alternator.

12-04-2011, 05:23 PM
Thanks Diablo I'll try calling Aprilia USA. BTW, my bike is an '08 Tuono R. It seems incomprehensible that such an integral part, and an expensive one at that, would fail at all, much less at 8K on the odometer. By seeing other posts on the matter there have been other owners with similar problems, both early on and later on.
I'm no mechanic by any stretch which is why I must rely on the shop for the tech stuff. And why I am seeking advice in this forum from those who are more experienced than I.
I also asked the question of failed stators of another well established shop, GP Motors in San Diego. They have seen failed stator systems. If that be the case it seems to me to be a design issue and should fall back on the manufacturer.

Bill in OKC
12-04-2011, 07:10 PM
I would think that if the battery is charged enough to start the bike, it would be strong enough to run the electronics. Some Aprilia ecus perform an internal voltage check and will shut the engine down completely if the voltage is too low, not sure about the '08 Tuono. In Oklahoma our pumps are labeled e10 or not and I've noticed an infrequent miss/hesitation when I am occasionally forced to fill with e10. It never misses a beat with real gas. How was your bike remapped?

12-04-2011, 08:00 PM
I believe map 2 by the same shop that's currently looking at the problem.

12-06-2011, 08:56 PM
I changed the stator on my 03 Mille not too long ago, and it is really not that hard of a job. You dont' need to be mechanically incline to do it, just have to follow the direction on the forum.
I did change it to the Rick's Stator instead of the OEM one, it has been running fine with no issue whatsoever.
I am just trying to save you a few hundred bucks here.

04-20-2012, 01:44 AM
I believe map 2 by the same shop that's currently looking at the problem.

Can you check your engine no. please?
Its located at the rear if the engine near the swingarm pivot point

04-20-2012, 04:38 AM
Having the same problem with stator on '06 model, AC test shows low outputs and ohm test shows continuity to the ground (1 wire - 0.9ohm, 2 wire - 0.6ohm, 3 wire - 1.5ohm) Already bought earlier model stator I will try follow Micah's stator conversion (http://alturl.com/6y7mb) He replied to me that he still runs it without problem.

04-20-2012, 11:38 AM
Keep in mind the only permanent fix is replacing the rotor/flywheel !

04-20-2012, 01:43 PM
have you checked the "brown conector"

Bill in OKC
04-20-2012, 03:14 PM
Along with all the good advice here I am reminded of a known problem with another euro vehicle I have. It is strongly recommended that if the battery gets low, not to rely on the charging system to charge it back up if at all possible. The alternator has a tendency to fry if it is "stressed"... Put the battery on a charger to do the heavy charging and let the charging system just keep it topped off. Not saying this applies to Aprilia? but it is a good idea to keep them on battery tenders in any case.