12-Pole vs 18-Pole: Need Definitive, Proven Answer

[Shaughn]

Hi Guys,

I need a definitive, "worked on my or my buddies bike" answer here, not an off-the-cuff, "can't see why it wouldn't work answer".

On my '78 GS750EC, the stator OEM is a 12-pole stator. As you may be aware, the aftermarket does not offer a 12-pole stator, despite 18-pole stators being commonly available. Both physically fit in the same space, however I do not know electrically if they are interchangable. I've seen reputable people on here state "Should work, doesn't matter" and I've seen other people state that there was no way that they should work interchangably, and at least one case where the 12/18 stator/rotor pole setup mix was the source of the charging problem.

Here's what Electrex says on the matter :

NOTE: These 8-valve GS750 models have a 12-pole three phase stator that has identical dimensions to the later 18-pole units (=ElectroSport ESG010). You can use an ESG010 in these older 8-valve models, but you will have to use the later model (80-83) GS850 flywheel. If you fail to change the flywheel the number of magnet poles does not match the stator and you will have NO OUTPUT from your new 18-pole stator.

OEM, a rotor is even more money than a stator, and I don't want to pay OEM on either, which is what led me to try to source aftermarket in the first place.

So, I see three options, but would love to hear others suggestions:
A) Rewind the stator, looks to cost about $80-100 now with copper prices, PLUS Time.

B) Buy OEM. Looking to be excess of $190, delivered.

C) Run it as is. This is what I'm thinking at least for this season. I've got a 'new' duaneage R/R. There is no way an under performing stator (last checked was 60/60/25VAC) can damage anything, right?? I can monitor the battery to keep me out of trouble, I think. Won't know the actual charging voltage until I button her back up, which I won't do until I have a direction I'm comfortable with.:-k

Any help/guidance here would be greatly appreciated.

 

[Guest]

mate, i see no reason why it wouldnt work!











just kidding


maybe you can find a used crank from a later model and use just the flywheel?

or, rewind the stator yourself?

 

[Shaughn]

maybe you can find a used crank from a later model and use just the flywheel?

or, rewind the stator yourself?

Rewinding the stator was my plan A, but time and money reasons had steered me back to aftermarket just to get it over with.

I've got some bids out on Ebay now for a 80 GS750 rotor (fiche states its the same as the gs850 one electrex mentions).
I'd feel a whole lot more comfortable had anyone else done this before, as I've no information on fitment issues.
I will post whatever I learn. Maybe this becomes the next fad mod for us with the 12poles.:-k

 

[tomm]

You have a fourth option. I replaced the 12-pole stator on my 78 GS750EC with a rebuilt 12-pole unit from Rick's Motorsports this past spring. They're in southern NH. Gave them a call to verify that they had one, and drove over to pick it up. I think it was $120 with the core. Not sure where you are in New England, but might be worth the drive. Otherwise, give them a call and order on line.

http://www.ricksmotorsportelectrics.com/

I looked at the conversion option as well, and decided against it because I heard the same thing about needing to change the rotor (made sense to me), and everything I read about removing the flywheel indicated that it was a real difficult task, plus it would have been more money overall. The after-market stator option just seemed easier.

Anyway, the rebuilt unit has been performing flawlessly all summer.

 

[Shaughn]

You have a fourth option. I replaced the 12-pole stator on my 78 GS750EC with a rebuilt 12-pole unit from Rick's Motorsports this past spring. ...

Thanks Tomm!

An wholly different option was exactly what I was hoping for.
They're listing them online for $155 now, but that's not taking the core credit into account.
I called them, and they are currently out of stock, but will re-wind mine for $125, shipped.
When its all said and done, DIY spirit notwithstanding, I want it done right and warrantied.

I think that's what I'm going to do.
I had heard Rick's Motorsports mentioned, but had gotten the faulty impression that they were the same as RMStator.

I live in Augusta, ME and am in the process of moving into a new apartment in Burlington, VT this week.
I've been through Manchester three times in the past month, and could've dropped it of then, oh well.
After putting in 600miles since Tuesday, I'm going to mail mine in.

 

[portdave]

update please....

update please....

Going thru some similar issues with same bike. What did you do and how has it been working? Thanks.

 

[bwringer]

I'm still trying to figure out why it makes a difference. I count six magnetic poles on either rotor (using a '79 GS850 engine and an '83 GS850 engine). So I'm a little mystified as to why you'd get no output with an 18 pole stator. Either way, it works out to three phases.

Just to blow a few minds: I worked on a boat engine a couple of times that had a seven pole stator. Four were used to generate power to charge the battery, run the lights, etc., three were used to power the engine control electronics, and one was used to generate the signal used by the engine control electronics.

Also, I note that Rick's lists the same (21-302) stator for all 79-83 GS850 models, while Electrosport has no listing for the earlier 12-pole models.

However, maybe they mean it simply won't work with the stock rectifier.

I'm not saying it's not true that the 12 and 18 pole stators won't interchange -- I'm just saying that I'd like to understand why.